878 Cpp - J-DESCj-desc.org/jpn/wp-content/uploads/2015/10/878-CPP.pdf · South China Sea Institute...

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IODP Proposal Cover Sheet -

Abstract

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Zhen Sun

Guangzhou164 Xingangxi Road

Continental Breakup, Serpentinization, COT, Rifting

Z. Sun, H. Larsen, C. Li, J. Lin, P. Wang, W. Ding, N. Hayman, S. Hsu, C. Huang, X. Huang, C. Lei,C. Lesher, J. Li, Q. Li, C. Liu, K. McIntosh , Y. Niu, X. Pang, M. Perez-Gussinye, Y. Qiu, J. Ren, H.Shi, J. Stock, X. Su, X. Tan, H. Van Avendonk, S. Wu, S. Xia, Y. Yan, B. Yao, Y. Yao, Y. Yeh, X.Zhang, M. Zhao, G. Zhong, D. Zhou,

This CPP addresses the mechanisms of lithosphere extension during continental breakup. State-of-the-art, deep reflectionseismic data show that the northern South China Sea (SCS) margin offers excellent drilling opportunities that can address theprocess of plate rupture at a non-volcanic rifted margin. The SCS margin shows similarities to the hyper-extendedIberia-Newfoundland margins, possibly including exhumed and serpentinized mantle within the Continent-Ocean-Transition(COT). However, recent modeling studies suggest that mechanisms of plate weakening other than serpentinization of thesub-continental lithospheric mantle exists. Two competing models for plate rupture (in the absence of excessively hotasthenospheric mantle) have widely different predictions for: (1) Crustal structure across the COT; (2) the time lag betweenbreakup and formation of igneous ocean crust; (3) the rates of extension; and (4) subsidence and thermal history. The drillingproposed will be able to firmly discriminate between these models. We propose four drill holes across a 150–200 km wide zoneof highly extended seaward-thinning crust with a well-imaged COT zone. Three 1423-1652 m deep holes will determine thenature of critical crustal entities within the COT, and constrain post-breakup crustal subsidence. These three holes will alsohelp constrain how soon after breakup did igneous crust start to form. A fourth 1102 m deep hole on the continental marginlandward of the COT will constrain the timing of rifting, rate of extension, and crustal subsidence. If serpentinized mantle isfound within the COT, this will lend support to the notion that the Iberia-type margin is not unique, and hence, that weakeningof the lithosphere by introducing water into the mantle may be a common process during continental breakup. If serpentinite isnot found, and alternatively, scientific drilling results for the first time are gained in support of an alternative model, this wouldbe an equally important accomplishment. Constraints on SCS formation and stratigraphy, including industry drilling, ODP Leg184 and IODP Expedition 349 drilling, the young (Paleogene) rifting of the margin, and absence of excessively thick post-riftsediments, allow us to effectively address these key topics by JOIDES Resolution drilling within a well-constrained setting.Initial spreading rate of ~ 2 cm/yr half-rate reduces the potential complexity of magma starved, slow-spread crust forming afterbreakup. The proposed drilling requires ~120 days of operations.

South China Sea Institute of Oceanology, Chinese Academy of Sciences

[email protected]

Testing Hypotheses for Lithosphere Thinning During Continental Breakup: Drilling at the South China SeaRifted Margin

South China Sea RiftingCpp878

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Site NamePosition

(Lat, Lon)

Water Depth (m)

Penetration (m)

Sed Bsm TotalBrief Site-specific Objectives

Scientific Objectives

Proposed Sites

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Non-standard measurements technology needed to achieve the proposed scientific objectives.

1. Determine the nature of the basement within critical crustal units across the Continent-Ocean-Transition (COT) of the SouthChina Sea rifted margin in order to discriminate between different competing models of breakup at non-volcanic riftedmargins. Specifically, to determine if the sub-continental lithospheric mantle was exhumed during plate rupture.

2. To examine the scale of time-lag between plate rupture and asthenospheric upwelling that allowed decompression meltingto generate igneous ocean crust.

3. To address the kinematics of breakup in terms of rate of extension and vertical crustal movements.

4. To improve the understanding of the Cenozoic regional tectonic and environmental development of the Southeast Asiamargin through new as well as existing ODP/IODP sediment records from the South China Sea basin.

Cpp878

SCSII-1A 18.4547167,116.13167

3715 1388 250 1638 Nature of basement: Exhumedserpentinized mantle? Or upper/lowercontinental crust, or igneousbasement? Time and environment offinal breakup, and subsequentsubsidence.High priority for proposal objective1,2,3,4.

SCSII-3B 18.93037, 115.85142 2928 1002 100 1102 Recover syn-rift and post-riftsedimentsTo constrain age, duration andenvironment of rifting and breakup.Subsidence historyHigh priority for proposal objectives3,4.

SCSII-3C 18.86948, 115.88742 2910 743 100 843 Recover syn-rift and post-riftsedimentsTo constrain age, duration andenvironment of rifting and breakup.Subsidence historyAlternate to 3B. High priority for


- - - - - - proposal objective 3, 4.

SCSII-8A 18.27145, 116.23985 3801 1323 100 1423 Nature of basement: Exhumedserpentinized mantle, or igneousocean crust. Paleodepth and initialsubsidence of the very earliest SCSocean basin.High priority for proposal objective 1,2.

SCSII-9A 18.14346, 116.31445 3864 1552 100 1652 Nature of oceanic crust: Was a robustmantle-melting regime establishedshortly after breakup or not?High priority for objectives 2,1.

SCSII-13A 18.10495, 116.06523 3841 1776 100 1876 Nature of oceanic crust: Was a robustmantle-melting regime establishedshortly after breakup or not.Alternate to 9A. High priority forproposal objectives 2, 1.

SCSII-12A 18.27419, 115.96566 3781 1826 100 1926 Nature of basement: exhumedserpentinized mantle, or igneousocean crust. Paleodepth and initialsubsidence of the very earliest SCSocean basin.Alternate to 8A. High priority forproposal objective 1,2.

SCSII-11A 18.41089, 115.88519 3739 1265 100 1365 Nature of basement:exhumedserpentinized mantle? Or upper/lowercontinental crust, or igneousbasement? Time and environment offinal breakup, and subsequentsubsidence.Alternate to 1A. High priority forobjectives 1,2,3,4.


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Testing Hypotheses for Lithosphere Thinning During Continental Breakup: Drilling at

the South China Sea Rifted Margin

Lead proponents: The SDRILL Team (Names listed alphabetically)

Hans Christian Larsen Marine geophysics, tectonics

Visiting Scholar, Tongji University; [email protected]

Chun-Feng Li Geophysics, tectonics

State Key Laboratory of Marine Geology, Tongji University; [email protected]

Jian Lin Marine geophysics

Woods Hole Oceanographic Institution; [email protected]

Zhen Sun* (Contact Person) Marine geology

South China Sea Institute of Oceanology, Chinese Academy of Sciences; [email protected]

Pinxian Wang Paleoceanography and regional geology

Tongji University; [email protected]

Co-proponents (Names listed alphabetically):

Weiwei Ding Marine geology

The Second Institute of Oceanography of the State Oceanic Administration; [email protected]

Nick Hayman Marine geology

Institute for Geophysics, University of Texas at Austin; [email protected]

Chi-Yue Huang Marine geology, paleoceanography

National Cheng Kung University; [email protected]

Shu-Kun Hsu Geophysics, tectonics

National Central University; [email protected]

Chao Lei Marine and petroleum geology

China University of Geosciences (Wuhan); [email protected]

Charles E. Lesher Petrology, geochemistry

University of California, Davis; [email protected]

Jiabiao Li Geophysics, tectonics

Second Institute of Oceanography of the State Oceanic Administration, [email protected]

Qianyu Li Paleontology, climate change


Char-Shine Liu Marine geophysics

National Taiwan University; [email protected]

Kirk McIntosh Marine geophysics


Yaoling Niu Petrology, geochemistry

Durham University; [email protected], [email protected]

Xiaolong Huang Petrology and Geochemistry

Guangzhou Institute of Geochemistry, Chinese Academy of Sciences; [email protected]

Xiong Pang Marine and petroleum geology

Chinese National Offshore Oil Corporation; [email protected]

Marta Perez-Gussinye Tectonics, geodynamics

University of London; [email protected]

Yan Qiu Marine geology and geophysics

Guangzhou Marine Geological Survey, Chinese Ministry of Land and Resources; [email protected]

Jianye Ren Marine and petroleum geology

China University of Geosciences (Wuhan); [email protected]

Hesheng Shi Marine and petroleum geology


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Joann Stock Marine geophysics

California Institute of Technology; [email protected]

Xin Su Paleontology

Chinese University of Geosciences (Beijing); [email protected]

Xiaodong Tan Paleomagnetics


Harm Van Avendonk Marine geophysics


Shiguo Wu Marine geophysics, sedimentology

Institute of Oceanology, Chinese Academy of Sciences; [email protected]

Shaohong Xia Marine geophysics


Yi Yan Geochemistry

Guangzhou Institute of Geochemistry, Chinese Academy of Sciences; [email protected]

Bochu Yao Marine geology and geophysics


Yongjian Yao Sequence stratigraphy, marine geology


Yi-Ching Yeh Marine geophysics

Taiwan Ocean Research Institute; [email protected]

Xiangtao Zhang Marine and petroleum geology


Minghui Zhao Marine geophysics


Guangfa Zhong Sedimentology, stratigraphy correlation


Di Zhou Marine geology


1. Introduction

We propose to drill across the South China Sea (SCS) margin (Fig. 1) in order to understand

the processes of rifting and eventual rupturing of the continental crust during breakup at a non-

volcanic rifted margin. In this new CPP submission, we have considered the helpful review

comments provided by SEP on the previous CPP-838, the results from the IODP Expedition 349

(January-March 2014), and incorporated valuable drilling operations advice from IODP TAMU.

As result of the latter, we now propose a drilling plan lasting ~ 120 days as opposed to a single-

leg 60-day operation. The scientific focus, as well as proposed drill sites remains essentially the

same as that of CPP-838. The expanded operations time required relates to: (1) Increased

basement penetration at key site(s): and (2) maintaining all four prime sites, three of these with

re-entry option and casing.

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While the primary focus of this proposal is to discriminate between possible models for plate

rupture, the drilling proposed will, along with ODP Leg 184 and IODP Expedition 349, as a

secondary objective provide much improved constraints on the Cenozoic development of the SE

Asian margin as recorded within the SCS basin. Drilling strategy, however, is entirely tailored to

the primary objective.

The SCS margins provide a valuable test bed for ODP-constrained models of breakup along

the Iberia and Newfoundland margins, or if other models hypothesized to exist, but not yet tested

by drilling, need be considered. Particularly important to this proposal is the exceptionally high-

quality seismic imaging (Courtesy of the Chinese National Offshore Oil Corporation (CNOOC))

of hyper-extended continental crust along the northern SCS margin. In these data we identify key

targets that can be reached using the JOIDES Resolution drilling vessel. Other advantages of the

SCS margin are its young age relative to North (and South) Atlantic margins, and that a relatively

fast spreading rate following breakup is indicated to have been in place. The latter reduces the

potential for complexity of ocean crust that formed by slow to ultra slow rates of plate divergence.

2. Background and Main Scientific Topic

The Ocean Drilling Program (ODP, 1985-2003) made a major effort along the rifted margins

of the North Atlantic to understand the processes of continental breakup (ODP Legs 103, 104,

149, 152, 163, 173, and 210). ODP drilling and related studies suggest that two end-members of

rifted margin exist:

1) Volcanic rifted margins characterized by massive igneous activity in a relatively short

period of time (~1-3 myr) during breakup and initial seafloor-spreading;

2) Magma-poor rifted margins where tectonic extension and thinning of the continental

lithosphere leads to exhumation and serpentinization of the sub-continental mantle

lithosphere.

The classical examples of volcanic rifted margins are the conjugate margins of East

Greenland and northwestern Europe (White and McKenzie, 1989). The presence of anomalously

hot asthenospheric mantle, in the North-East Atlantic linked to the Iceland mantle plume (Larsen

and Saunders, 1998; Holbrook et al., 2001; Nielsen et al., 2002), seems to play a fundamental

role in the formation of volcanic rifted margins and associated massive igneous activity.

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Fig. 1 Seismic data coverage and magnetic anomalies of the South China Sea Basin. Black lines: OBS data.

Other seismic lines mostly MCS reflection seismic data. Red solid stars are locations of the proposed primary

drilling sites, yellow stars are alternate sites. Their names were abbreviated by deleting ‘SCSII-‘ due to limited

spaces. Two seismic lines on the southern SCS margin (yellow lines) are in approximately conjugate position to

our study area; these lines are shown in Fig. 11. Leg 184 and Expedition 349 drill sites shown with site number.

For more details, see Fig. 2.

The latter is easily recognizable within both reflection seismic data (e.g., seaward-dipping

reflector sequences; Larsen and Saunders, 1998) and in crustal seismic velocity data (e.g.,

Holbrook et al., 2001). However, the crustal structure of SCS rifted margins show none of the

typical volcanic rifted margin features. On the contrary, the SCS margins show a number of

similarities to that of the Iberia, magma-poor margin (e.g., Franke, 2013; Barckhausen et al.,

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2014). The drilling strategy of this proposal is therefore tailored to acquire samples critical to

further our understanding of the formation of non-volcanic rifted margins: Is the extreme magma-

poor Iberia margin a widespread alternative to volcanic rifted margin formation? Or is there a

‘third’ way as modeling may suggest (e.g., Huismans and Beaumont, 2011).

The ODP sampled the magma-poor Iberia-Newfoundland conjugate margins that formed

between ~130 and ~110 Ma. ODP Leg 103 at the Galicia margin discovered serpentinized mantle

to be present within the transition zone between thinned continental lithosphere and (interpreted)

oceanic crust (Boillot et al., 1988). ODP Legs 149 and 173 along the Iberia margin south of the

Galicia margin confirmed similar structures to be present (Whitmarsh et al., 1996, Beslier et al.,

2001). Off Iberia, however, drilling also showed that the oldest ocean crust (crust as defined by

seismic velocity structure) along the margin consists of serpentinized mantle. This “crust” is now

generally accepted to have formed by ultra-slow spreading. The ultra-slow spreading system is

prone to produce only limited amounts of igneous crust due to the effect of conductive cooling of

the slow-rising asthenospheric mantle (Forsyth, 1993, Cannat et al., 2009; Dick et al., 2003,

2010). ODP Leg 210 found that serpentinized mantle is also present at the conjugate

Newfoundland margin (Tucholke et al., 2007), adding further drilling evidence for existence of

this type of margin.

Drilling results and associated geophysical work therefore suggest that along these magma-

poor margins, profound tectonic extension of the crust (‘hyper extension’) dramatically thins the

crust prior to breakup, and at some point allows water to access the sub-continental lithospheric

mantle through crust-cutting faults. Underpinning of the final and complete rupture of the

continental lithosphere by profound mechanical weakening of the mantle lithosphere by

serpentinization is therefore suggested (Whitmarsh et al., 2001; Pérez-Gussinyé and Reston, 2001;

Pérez-Gussinyé et al., 2006; Reston, 2009; Sutra and Manatschal, 2012).

It therefore can be hypothesized that weakening of the continental lithosphere to allow plate

rupture to take place may follow two distinctly different paths:

1) Convective heating (plume type) of the mantle lithosphere and associated excess magmatism

during breakup and early ocean basin formation.

2) Introduction of water into the sub-continental lithospheric mantle through deep, crust-cutting

faults with none, or only very limited igneous activity during breakup.

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Volcanic rifted margins are quite easily and firmly recognized by reflection seismic data.

They are found within margins of the North and South Atlantic, off Antarctica, and along the

Indian Ocean (Franke, 2013). This strongly suggests that (excessive) thermally induced

weakening of the continental lithosphere during breakup is a common process during geological

history.

Similarly, is seismic imaging of ‘hyper-extended’ crust along several other rifted margins

sufficient to equate these with ‘Iberia-type’ margin formation? And by implication, is

serpentinization of the sub-continental mantle lithosphere another common driver of lithospheric

rupture? The pivotal feature required for concluding this is the presence at the outermost

continental margin of serpentinite bodies representing (former) sub-continental mantle

lithosphere. However, this critical feature is not easily tractable on seismic data, and is only

confirmed by drilling at the conjugate Iberia-Newfoundland margins.

So key questions to answer by drilling are: (1) Can exhumation of sub-continental

lithosphere during breakup be verified on other margins? (2) If so, can igneous ocean crust,

unlike Iberia margin, form shortly after breakup, provided the initial sea-floor spreading rate was

high enough (> 1cm/yr; half-rate) to produce significant mantle melting? Alternatively, is there a

third type of margin in which neither plume-type thermal weakening, nor serpentization of the

sub-continental lithospheric mantle operates during breakup as suggested by modeling (Huismans

and Beaumont, 2011, Brune et al., 2014)?

Other key parameters not traceable by seismic data are the rate of extension and the

subsidence during breakup. The rate of extension will amend the mechanical model for plate

rupture with a kinematic dimension. Kinematics, as well as the distribution (time and space) of

margin subsidence, is important to possibly discriminate between different models of margin

formation.

A relatively young age of the SCS margins, excellent data coverage including drill holes

(ODP/IODP/industry), and seismic imaging clarity of crustal structure across the SCS margins

suggest that the SCS margins as an excellent test bed of the ‘mantle wetting’ hypothesis (Iberia-

type margin), or alternatively, provide the first scientific coring in support of an alternative

margin model.

This proposal therefore has three primary scientific objectives:

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1) Determine the nature of the basement within critical crustal units across the Continent-

Ocean-Transition (COT) of the South China Sea rifted margin in order to discriminate

between different competing models of breakup at non-volcanic rifted margins. Specifically,

determine if the sub-continental lithospheric mantle was exhumed during plate rupture.

2) Examine the scale of time-lag between plate rupture and asthenospheric upwelling that

allowed decompression melting to generate igneous ocean crust.

3) Address the kinematics of breakup in terms of rate of extension, and vertical crustal

movements.

A fourth and secondary objective that can be addressed by the planned drilling is:

4) Improve the understanding of the Cenozoic regional tectonic and environmental

development of the SE Asia margin through new as well as existing ODP/IODP sediment

records from the South China Sea basin.

3. Geological Setting of the Proposed Drilling Transect

The SCS is a modestly sized, young ocean basin that formed along the eastern boundary of

the Eurasian plate during mid- to late Cenozoic time (Fig. 1). The SCS deep region can be

divided into the Eastern and Southwestern Sub-basins. In this proposal we address drilling targets

along a cross-margin transect within the Eastern Sub-basin. This sub-basin is generally held to

have formed first (~ 32-30 Ma), and with a later expansion of spreading into the Southwestern

Sub-basin (Briais et al., 1993; Barckhausen and Roeser, 2004; Li et al., 2012; Franke et al., 2013).

The continental crust that gave way to form the SCS was accreted to the Asian margin during

the Mesozoic (Zhou and Li, 2000; Zhou et al., 2008; Li et al., 2012). Within approximately 80

myr, this new continental lithosphere underwent extensive rifting during the Paleogene, most

likely from early Eocene time (~45 Ma) to Early Oligocene (32 Ma, Li et al., 2012, 2013;

Barckhausen et al., 2014; unpublished industry borehole data). There are different and as yet

unresolved hypotheses for the origin of the extensional forces that led to breakup, such as rifting

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caused by subduction zone roll-back (Rangin et al., 1990), slab pull of the proto-South China Sea

(Taylor and Hayes, 1983), or extrusion tectonics related to indentation of the Indian sub-continent

to Asia (e.g., Tapponnier et al., 1982). However, the focus of our drilling proposal is to take

advantage of the SCS margins as a natural laboratory to understand the impact on the continental

lithosphere by the extensional forces, not the origin of the stress field. That said, better constraints

on the timing, duration and mechanism of lithosphere extension is likely to weigh in on this topic

too.

Ocean floor formation of the SCS started in the Early Oligocene, with the oldest interpreted

magnetic anomaly being C12n (~32 Ma) within the eastern-most part of the Eastern Sub-basin

(Briais et al., 1993; Li et al., 2013, Franke et al., 2013). Seafloor spreading ceased within the

middle Miocene (Taylor and Hayes, 1980; 1983; Briais et al., 1993; Barckhausen and Roeser,

2004, Barckhausen et al, 2014). Initial spreading rate is modeled to be ~2 cm/yr increasing to

~2.5cm/yr (half-rate; Lin et al. 2013; Jian Lin, personal communication), i.e., a slow to

intermediate spreading rate system. Subduction of the eastern part of the SCS basin started at ~15

Ma along the Manila trench (Li et al., 2013). However, this post-spreading tectonism did not

affect the margin segments we propose to drill. For a more complete review of the regional

setting and tectonic development see Shi and Li (2012), Li et al. (2013), and Franke et al. (2013).

The recently completed IODP Expedition 349 to the SCS basin targeted the spreading history

of the SCS. It successfully recovered samples from near the extinct axes of both the Eastern (Site

U1431) and Southwestern (Sites U1433 and U1434) Sub-basins, as well as from a marginal high

(Site U1435) close to the continent-ocean transition at the northern margin of the Eastern Sub-

basin (Figs. 1, 2).

Ocean floor type (MORB) basalts were recovered from the center of both the Eastern and

Southwestern Sub-basins. Shipboard data (see Expedition Reports of Sites U1431, U1433 and

U1434; http://iodp.tamu.edu/scienceops/expeditions/south_china_sea.html) indicate that

cessation of spreading in the SCS took place around 13-17 Ma, providing an important

calibration point for modeling seafloor-spreading magnetic anomalies across the basin.

Site U1435 drilled during IODP Expedition 349 is located on a highly elevated, narrow, and

isolated seamount-like structure just landwards of the interpreted magnetic Chron C11N (~31 Ma;

Fig. 2). Close to 300 m of sediment was recovered at Site U1435.

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Fig. 2 North SCS margin with seismic coverage of 2D, time-migrated MCS reflection seismic data and OBS data

(3D data not shown). The key seismic lines used for planning of the drilling transect are marked in thick blue

and shown in Figs. 3, 4. Proposed drill sites for this proposal are shown in red (primary sites) and white stars

(alternate sites). Site 1148 of ODP Leg 184, and Sites U1432 (failed to collect core) and U1435 are shown in

orange or yellow squares. Magnetic lineations within the ocean crust are shown in red. Magnetic chron

number is after Briais et al. (1993).

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An upper, deep marine sequence of Pleistocene to Early Oligocene age is underlain by

shallow water (or possibly lacustrine) sediments of inferred Late Eocene to Early Oligocene age

(lower sequence barren of microfossils). This lowermost succession shows increasing dip with

depth. It is interpreted as syn-rift deposits reflecting (waning) tectonic rotation as rifting

progresses towards final breakup. Lacustrine sediments of Eocene age have also been recovered

by industry drilling further inland on the northern SCS margin; however, they were not expected

to be present at Site U1435 located at the outermost margin. By implication of the age and nature

of the oldest overlying sediments, basement in this location is interpreted to be of continental

origin. This may suggest that the continent-ocean boundary is located between Site U1435 and

the nearby (interpreted) seafloor-spreading anomaly C11.

ODP Site 1148 (ODP Leg 184) is quite close to the new IODP Site U1435 (Fig. 2). The

oldest sediments recovered at ODP Site 1148 are deep marine and also of Early Oligocene age

(~33 Ma; Wang et al., 2000), but they could be underlain by older, shallow water sediments

similar to those of Site U1435 (seismic data insufficient at Site 1148). The combined findings at

Sites 1148 and U1435 therefore suggest that along this part of the outer SCS margin, rapid

subsidence from shallow (or even lacustrine) marine deposition to a deep-water environment was

initiated from around the Eocene-Oligocene boundary (~34 Ma). However, the core sequences at

both Site 1148 and Site 1435 (in particular) cannot easily, or at all (1435), be traced more

regionally.

4. Margin Structure within Drilling Transect

We have chosen a drilling transect located about 50 km west of the recently drilled Site

U1435 (Fig. 2) at the northern SCS margin of the Eastern Sub-basin. Seismic imaging quality as

well as scientific reasons favor this choice of transect location. The oldest magnetic anomaly

identified on this part of the northern margin is C11 (~30 Ma), slightly younger (~1-2 myr) than

further east along the northern SCS margin where C12 is interpreted to be present.

Regional interpretation of the large set of industry data, including 3D coverage, shows that

the chosen transect is centrally located within a margin tectonic segment that exhibits a broad

zone (~150–200 km) of across-margin crustal necking and hyper-extension prior to breakup.

Further east around Site U1435, the zone of crustal necking may be narrower, implying a more

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rapid change from continental to oceanic crust; this would be consistent with the recent Site

U1435 findings. Interestingly, similar margin segmentation is suggested for the Iberia-Galicia

Bank margin with the Iberia margin representing the wide zone of crustal necking, and the

Galicia the narrower zone (Sutra and Manatschal, 2012).

Our proposed drilling transect is defined by two parallel seismic lines ~25 km apart,

providing excellent seismic imaging (Figs. 2, 3 and 4). Their general crustal structure is quite

similar. However, the two lines differ in terms of syn- to post-rift sediment cover over the Outer

Margin High (OMH), which is far less on Line 1530 than on Line 1555. Also, the OMH is more

massive (intact?) on Line 1555 (Fig. 3) than on Line 1530 (Fig. 4).

We define the Continent-Ocean-Transition (COT) as the zone in which the outermost,

extended continental lithosphere is replaced by crust (and lithosphere) that formed within a

focused zone (i.e., spreading ridge) in a steady-state fashion. The latter can include continuous

tectonic exhumation and serpentinization of rising asthenospheric mantle (not sub-continental);

accretion of normal igneous ocean crust, or a mixture of these two processes. So when we refer to

ocean crust, this does not necessarily imply igneous ocean crust.

Clear Moho reflections (Figs. 3 and 4) show distinct thinning of the continental crust towards

the COT. A general layering of upper, middle, and lower crust is imaged on both profiles. The

lower crust is acoustically transparent, and only about 6 km thick on both lines. Lower crust with

a similar thickness and acoustic appearance is reported from the northeastern SCS margin

(McIntosh et al., 2013, Lester et al., 2013). This lower crust is indicated to thin towards the COT,

but seismic data are not conclusive in this regard.

The upper crust shows numerous extensional, low-angle detachment faults soling out at mid-

crustal level. This fault system generated a number of deep half-grabens filled with syn-rift

sediments, subsequently covered by post-rift sediments. The syn-rift sediments are topped by a

breakup unconformity (T70 in Fig. 3). Industry data (distant wells; only cuttings and logging data)

may suggest an age around 32 Ma, but this need to be verified by coring data (see Fig. 3 caption

for more details). This unconformity reflects the end of the main crustal extension, but it is not

necessarily isochronous across the margin and could be younger towards the outer margin. A

younger, widely distributed unconformity (T60) is also shown in Figs. 3 and 4 (see figure

captions for more details). It likely reflects differentiation into a shallower continental margin and

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Fig. 3 Deep crustal, time-migrated seismic reflection data without (a) and with interpretation (b). Note the rather thin lower crust (two layers) above a strong Moho reflector that can be followed oceanward. Moho reflection is weak to absent seawards from around the interpreted continent-ocean boundary (COT). Wide-angle seismic data (Yan et al., 2001) confirm ~ 6 km thick ocean type crust to be present seaward of the COT. A large detachment fault ~ 150 km inland of the COT separates more stable crust landwards from that of highly extended crust in the seaward. An outer margin high (OMH) is a fairly consistent feature margin along this margin segment. Key seismic unconformities are shown in purple (T70; ~ 32 Ma breakup unconformity?) and blue (T60; ~23 Ma regional basin event). These ages are inferred from long distance (>100 km) correlation of seismic unconformities with industry holes and Site 1148 (T60). These ages need confirmation by coring, and are only tentative. Tg (green): Basement. Proposed primary drill sites shown. Approximate position of seafloor magnetic anomalies with chron numbers are shown by arrows. See Fig. 5 for a schematic interpretation of the entire profile. Seismic data is from line 04ec1555-08ec1555 (Courtesy CNOOC). Location of line is shown in Fig. 2.

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Fig. 4 Deep crustal, time-migrated seismic reflection data without (a) and with interpretation (b). The line is located parallel to and 25 km southwest of

line 1555 shown in Fig. 3. The crustal structure shown by the two lines is quite similar. However, the outer margin high (OMH) is less massive on this line.

The Moho is better imaged from below the OMH and across the COT. A large detachment fault ~ 200 km inland of the COT fault separates more stable

crust landwards from that of highly extended crust seawards. Key seismic unconformities shown in purple (T70; ~ 32 Ma) and blue (T60; ~23 Ma). See

also figure caption of Fig. 3. Tg (green): Basement. Proposed primary drill sites shown. Approximate position of seafloor magnetic anomalies with chron

number shown by arrows. See Fig. 5 for a schematic interpretation of the entire profile. Seismic data from line 04ec1555-08ec1555 (Courtesy CNOOC).

Location of line in Fig. 2. Approximate position of magnetic seafloor magnetic anomalies is shown by arrows with chron number. Proposed (alternate)

drill sites are also shown. Seismic data is from line 04ec1530-08ec1530 (Courtesy CNOOC). Location of line is shown in Fig. 2.

14

a true, deep oceanic basin. It may correspond to a ~23 Ma old hiatus found at Site 1148 (Wang et

al., 2000). Lack of seismic tie to Site 1435 prevents comparison with this site.

The distinct OMH of Line 1555 is less well developed on Line 1530, where narrow,

separated basement highs appear around CDP 4300 and CDP 6600 (Fig. 4). These basement

structures are quite reminiscent of the structure drilled at Site U1435, but are here located more

inland of the interpreted magnetic anomaly C11 than Site U1435 (Fig. 2). This would be

consistent with the interpretation of a wider zone of crustal necking within this margin segment,

compared to that of Site U1435.

Seaward of the OMH, both profiles (Figs. 3 and 4) show the presence of a basement high

within the COT, close to, but landward of the interpreted boundary between continental and

oceanic lithosphere. The nature of these basement highs seems different from that of the OMH

fault blocks. The structure is more dome like, with neither normal faults, nor syn-rift half-grabens

easily observed on the landward facing part of these structures (Site SCS-II 1A, 11A targets).

Note that magnetic anomaly C11 is projected to almost overlap (seaward part) with this structure

(Figs. 2. 3). Excluding sediments, the crust below this outermost basement high is only around

2.5 seconds two-way travel time (TWTT) thick, or about 8 km using OBS velocity constraints of

Yan et al. (2001), Wang et al. (2005), and Wei et al. (2011). Seawards of the COT, the crust has

fairly uniform thickness of just below 2 seconds TWTT (~ 6 km), consistent with the

interpretation of this being oceanic crust (Yan et al., 2001). This COT zone is a key objective of

our proposed drilling.

A summary of key tectonic features based on Line 1555 is shown in Fig. 5. In this

interpretation, the normal faults of the upper, brittle crust sole out within a main detachment zone

located above or within the middle crust. It may seem counter-intuitive that faulting is not

penetrating deeper into ductile lower crust. Despite the generally high data quality, this could

simply be an imaging problem. Or it could indicate strong decoupling between upper and lower

crustal extension. The deeper crust, except for the base of the crust, is not well imaged below the

COT (Figs. 3 and 4). Hence, deep crust-cutting faults could hide from seismic imaging in this

location.

Another possibility is that the main detachment zone itself became exhumed during final

breakup. This would imply that (1) the former position of the main detachment zone actually was

15

Fig. 5 Simplified interpretation of the seismic data shown in Figs. 3. Note the seaward shallowing of Moho,

and presence of major detachment faults that seem to sole out between the upper and middle/lower crust.

While the general location of the COT (marked white with question marks) is well constrained by both seismic

profiles (Figs. 3, 4), the details of crustal structure within the COT are not well constrained. The seismic line in

Fig. 4 images this zone slightly better, in particular regarding Moho. The following options are discussed in the

main text: Serpentinite lower continental crust, or igneous material (intrusion) related to breakup. If

serpentinite, the Moho reflector below the landward part of the COT could be a serpentinization front within

the sub-continental mantle lithosphere. If serpentinite is recovered (Site 1A), the original detachment fault(s)

must have been exhumed and the basement at Site1A form a core-complex.

over the top of the outermost basement high (i.e., Sites SCSII-1A and 11A); (2) its further

seaward (i.e., original down-dip) continuation is to be found ocean-ward of Site 1A around Site

8A; or (3) perhaps the main detachment zone was even transposed onto the conjugate margin

during final breakup. If the main detachment fault actually has been exhumed, the outermost

continental part of the COT around Site 1A must consist of either lower crust or serpentinized

sub-continental mantle lithosphere. An apparent seaward continuation of the Moho (most clear in

Fig. 4) might support lower crust to be preserved below drill Site 1A. Alternatively, the “Moho”

16

Fig. 6 Schematic development (a-d) of continental breakup initiated by a simple shear along a deep, low angle

fault. Stages b to d are slightly modified from Huismans and Beaumont (2011) and illustrate modeling based

stages of extension at magma poor rifted margins of the Iberia-Newfoundland type. 1: Syn- and post-rift

sediments (yellow); 2: Upper continental crust (brown); 3: Lower continental crust (white; two layers); 4:

Lithospheric mantle (light blue); 5: Serpentinized mantle (cross-hatching); 6: Asthenospheric mantle (purple);

7: Igneous oceanic crust (green); and S: Proposed drilling targets 1A, 8A, 9A. LP: Lower plate. UP: Upper plate.

Key features of the final margin structure are: (i) thinning of the lower crust; (ii) juxtaposition of upper crustal

structural units to lower crust or serpentinized mantle (Site 1A); and (iii) fairly wide zone of serpentinite crust

(Sites 8A, 9A?) between the outer margin and igneous oceanic crust. The northern SCS margin shows a

striking general similarity to the upper plate margin of stage d. However, only sampling by drilling of the key

structural units can discriminate between this and other possible models.

17

in this zone below the COT may be a serpentinization front. Sampling of basement at Site 1A is

therefore pivotal to constrain crustal structure and critical aspects of the extension process.

In summary, these observations have provided constraints to locate the COT to within less

than 40 km. But without deep sampling of the distinct basement structures defined by the seismic

data, the true nature of the COT will remain elusive, preventing us from testing if the SCS

margin is another example of the Iberia type margin or not. Before presenting our detailed

drilling strategy (Section 6), we first discuss various model predictions that guide our drilling

priorities.

5. Critical Modeling Predictions and Parameters to be Tested

Huismans and Beaumont (2009, 2011) modeled two scenarios for the formation of rifted

margins in the absence of anomalously hot asthenospheric mantle. One scenario (Type-I of

Huismans and Beaumont) is the Iberia-Newfoundland type margins in which preferential

lithosphere thinning initially occurs in the (upper) crust, with extensional faults eventually cutting

into the mantle and mechanically weakening the mantle by serpentinization. Key aspects of their

modeling results are summarized in Fig. 6.

Similarities between the modeling (Fig. 6) and the interpretation of the general margin

structure of the SCS (Fig. 5) are quite striking. However, Huismans and Beaumont (2011)

proposed an alternative (Type-II) model in which initial and preferential stretching of the mantle

lithosphere and lower crust leads to plate rupture without exhumation of the sub-continental

mantle and associated serpentinization during breakup. The two models result in distinctly

different structures across the outer continental margin and into ocean crust.

The Iberia-type model (Type-I) is predicted to show a significant hiatus between the final

breakup and development of truly igneous oceanic crust. Correspondingly, a wide zone of mainly

serpentinized asthenospheric mantle makes up the new ocean crust, similar to crust forming at

ultra-slow spreading centers (Cannat et al., 2009; Dick et al., 2003, 2010). This would be

consistent with the very low spreading rate (~0.6 cm/yr half-rate) of early ocean crust off Iberia-

Newfoundland (Whitmarsh et al., 1996; Péron-Pinvidic and Manatschal, 2012; Tucholke and

Sibuet, 2007). However, these initial low spreading rates by themselves could be speculated to be,

18

if not the main, then a supplementary driver for the extensive formation of crust formed by

serpentinization of the mantle.

The other model (Type-II) predicts that a spreading center generating igneous ocean crust

will form shortly, if not instantly after breakup. This is because thinning of the mantle lithosphere

initially is favored over crustal thinning, allowing the asthenospheric mantle to rise and melt at an

earlier stage within the process of breakup. This latter difference also manifests itself in a

different thermal and subsidence history, and potential for rift-related magmatism (Huismans and

Beaumont, 2011; Brune et al., 2014).

In summary, two simplified models might exist: One possible type of COT will have

serpentinized sub-continental lithospheric mantle being replaced seaward by serpentinized

asthenospheric mantle; another COB type will show thin continental crust being replaced seaward

by igneous oceanic crust. While the location of the COT is basically the same in the two models,

the structure of the COT is very different. Only by drilling can we differentiate between these

fundamentally different models for plate rupture. Three drilling locations across the COT (Figs. 5

and 6) target these critical details of the COT. A fourth high priority site is located landward of

the COT. This site (3B) will sample syn- to post rift sediments providing constraints on the

timing and the rates of extension, and will help constrain the subsidence history. These are

parameters are needed to develop a kinematic dimension to the mechanics of plate rupture. The

site will also provide a (potential) lead into the thermal history of the margin during rifting.

6. Planned Drilling Sites

Four primary sites (with alternates) are included in this proposal. The operations plan

developed by IODP TAMU requires ~ 120 days of ship time in order to achieve all four sites (see

also section 10). Primary drilling sites are all located on Line 1555 (Figs. 2, 3, 4, and 5).

Seismic Line 1555 allows us to define deep basin sites as well as one important OMH site on

a single margin transect. Alternate sites are located on Line 1530. Both seismic lines show similar

structures around the COT suggesting that these are continuous for at least 25 km along strike.

However, comparing Site 1A on line 1555 with its alternate Site 11A on line 1530 (see specific

site descriptions in the following) suggests that the very late syn- to early post-rift sequence is

better preserved at Site 1A. Also, line 1555 offers better targets on the OMH (Site 3B).

19

Accordingly, line 1555 is our key transect line, with line 1530 offering alternate sites (e.g., safety

review, operations issues, initial drilling results).

Specific key questions to be answered by the primary four sites are:

Q1: What is the nature of the outermost continental margin crust: (a) Serpentinized sub-

continental mantle lithosphere, (b) original continental crustal material and if so, lower to middle

crust, or upper crust? Sites 1A, 8A will be prime sites in this regard.

Q2: How soon after final plate rupture did igneous ocean crust form, and under what type of

mantle melting conditions? Site 9 and potentially Site 8A will address this question.

Q3: Or is there a zone of serpentinized asthenospheric mantle (i.e., slow-spreading type crust)

present between the outermost edge of the continental margin and igneous ocean crust? Site 9A

(possibly also 8A) will address this question.

Q4: What is the rifting and post-rifting history in terms of timing, rate of extension, and

subsidence? Sites 3B combined with 1A (alternate 11A) will specifically address these questions.

Site SCSII-1A (11A alternate)

Site 1A is planned to be drilled first. It will target (Fig. 7) the nature of the basement in a

position of the COT most critical to distinguish between different models of margin formation.

Furthermore, in this location, late syn-rift to early post-rift deposits are interpreted to be present

over the basement; these constitute a second, important sampling target. The entire hole will be

cored, and is planned for deepening into basement for as much as 250 m. See section 10 for more

details.

Sites 1A and alternate Site 11A are both located around the interpreted magnetic lineation

C11 (~ 30 Ma), and interpreted to represent the same structural unit within the COT. However,

overlap with C11 may not prove that the ocean crust, per se, extends this far landward. Firstly,

mapping of the low-amplitude, pre-C9 anomalies is associated with some uncertainty. Secondly,

during the process of serpentinization, seafloor-spreading like magnetic stripe zones can develop

through the mineral reactions related to serpentinization. However, because the prime objective is

to understand the process of breakup, not the exact age of breakup, these uncertainties are not

critical for our drilling strategy.

20

Fig. 7 Seismic images of proposed Site SCSII-1A, 11A (alternate). These are alternate sites placed on parallel

seismic lines, and show quite similar structures. The key target is the nature of this basement high within the

COT in order to resolve its nature. As discussed in the main text, three interpretations could be consistent

with seismic data (setting, image and velocities): Serpentinite, lower continental crust or igneous body. Note

that a thin sequence of (interpreted) late syn-rift sediments is present just landward of Site 1A, and likely

extends to the location of Site 1A (not at Site 11A, however). This and younger post-rift show draping over the

structure suggesting that the structure moved vertically during late rifting and early syn-rift stage. Green line

(Tg): basement. Purple: Unconformity T70 (~ 32 Ma breakup unconformity?). Blue: Unconformity T60 (~23 Ma

regional basin event). See figure caption Fig. 3 for discussion of the ages of these unconformities.

Several outcomes from basement drilling can be envisaged, each of which will support specific

hypotheses for breakup:

1) Serpentinized sub-continental mantle. This would strongly support the notion of Iberia-type

margin formation as a potentially common process of plate rupture at magma-poor rifted

margins. It would also suggest that the down-dip part of the main zone of detachment faulting

21

responsible for crustal extension became exhumed during final breakup, and possibly

transposed to the conjugate margin. Alternatively, the fault could re-appear seaward of the

basement high within the center of the COT (features around the COB at Line 1530 could be

interpreted this way). To find serpentinite basement would further imply that the interpreted

Moho reflection below this part of the COT is a serpentinization front within sub-continental

mantle lithosphere. This in turn would indicate how deep into the mantle water was able to

penetrate in this setting.

2) Continental crustal material. This outcome would be intriguing since it would demonstrate

the preservation of continental crust extremely close to ocean crust (igneous or slow-

spreading, serpentinite type). It would imply that the Moho reflection below this landward

part of the COT is close to the original continental Moho, and also that the main zone of

detachment faulting would continue below the basement high (not visible on seismic data).

The character of the continental crust, deeply exhumed or upper crust, would constrain how

deep detachment faulting went in this place. Recovery of lower (former) ductile crust would

represent a unique, in situ sampling of such material.

3) Igneous rocks of breakup age. While we consider this to be quite unlikely, it would be an

important finding, strongly suggesting that this is not an Iberia type margin.. On the contrary,

it might suggest that a robust mantle-melting regime was in place from the very beginning, if

not before, the final plate rupture. It would favor the type of depth-depending breakup process

modeled by Huismans and Beaumont (2011). Finding igneous material at Site 1A would

allow us to constrain timing of igneous activity, explore mantle source, study degree of

mantle melting, and identify possible continental contamination of igneous material.

Sites SCSII-8A and 9A

Both Sites 8A and 9A (Figs. 8, 9) target basement highs within crust that in a regional

context (i.e., magnetic anomalies, crustal thickness) is considered ‘oceanic’ in nature. However,

we regard the likelihood of true igneous oceanic crust to be present at Site 8A as limited, but

somewhat higher for Site 9A.


22

There are several possible outcomes from drilling at Site 8A (Fig. 8):

Fig. 8 Seismic images of proposed Site SCSII-8A (primary) and 12A (alternate). These sites are placed on

parallel seismic lines, and show quite similar structures. The key target is the nature of this basement high

within the COT. As discussed in the main text, three interpretations could be consistent with seismic data and

general setting: Serpentinite, continental crust or igneous ocean crust. Tg (green): Basement. T60 (blue):

regional basin unconformity. See Figure 3 caption for more details on T60.

1) Serpentinite with origin in the sub-continental mantle: This would provide support for this

margin to represent an Iberia-type margin, imply that the transition to oceanic crust is placed

more seaward than suggested by interpretation of magnetic anomalies, and, pending results

from 1A, indicate that subcontinental lithosphere was exhumed to a significant extent during

breakup (i.e., if also present at 1A).

2) Igneous oceanic crust: This would strengthen the case for an alternative (to Iberia-type)

margin development, perhaps supporting the Type-II stretching model of Huismans and

Beaumont (2011).

23

3) Serpentinite with origin in the asthenospheric mantle (i.e., ‘ocean crust’): Pending results

from Site 1A, this would suggest that either sub-continental mantle was not exhumed during

breakup, or at least only to a very limited extent, before asthenospheric mantle could rise, but

not (yet) generate significant mantle melting.

4) Continental crust. An intriguing (but less likely) possibility is that Site 8A in fact could be a

completely detached piece of (upper?) continental crust tectonically transported to this

position along a former detachment zone that was exhumed at Site 1A. Some details along

seismic line 1530 (Site 12A) could be consistent with such a finding. Drilling at Site 8A is

therefore not our initial priority, as it could be misleading, and would not constrain the nature

of the basement at first priority Site 1A.

Fig. 9 Seismic images of proposed Site SCSII-9A (primary) and 13A (alternate). These are alternate sites placed

on parallel seismic lines, and show quite similar structures. The key target is the nature of this basement high

within the COT. As discussed in the main text, two interpretations could be consistent with seismic data and

general setting: Serpentinite or igneous oceanic crust.


24

This site (Fig. 9) will address whether a robust mantle-melting regime was established

shortly after breakup. The modeling by Huismans and Beaumont (2011) suggests that for an

Iberia-type margin, this would not be the case. On the contrary, a fairly extensive hiatus between

final plate rupture and development of igneous crust should exist.

The following outcomes can be expected:

1) Igneous oceanic crust: This would prove that mantle melting started quite soon after final

breakup, and seemingly be at odds with Iberia-type margin formation. Pending other drilling

results (nature of crust at Sites 1A and 8A), it could be consistent with the Type-II model of

Huismans and Beaumont (2011). Samples of igneous crust in this location would provide

geochemical constraints on initial mantle melting conditions below the emerging spreading

center, and to what degree continental crustal contamination is present at this stage of basin

formation. The latter would contribute to illuminate the process from very latest stages of

breakup to seafloor spreading.

2) Serpentinized asthenospheric mantle: This would suggest that steady-state accretion of new

oceanic crust, albeit non-igneous, has started. The further seaward extent of such crust until

igneous crust starts to form might then be assessed based on geophysical data (e.g., wide-

angle seismic data, deep-towed magnetics and gravity) calibrated to the drilling results from

Site 9A and Sites 1A, 8A.

3) Serpentinite of sub-continental mantle origin: This would indicate that a broad zone of the

continental lithospheric mantle became exhumed during breakup. The original detachment

zone between a possible lower and upper plate might have penetrated deeply into the

lithospheric mantle, possibly at a relative low angle in order for this to produce such a broad

zone of sub-continental mantle exhumation (of course, more complex, multiple generation

faulting might have had the same effect; e.g., Ranero and Pérez-Gussinyé, 2010).

Site SCSII-3B (3C alternate)

This site (Fig. 10) will sample the sequence of post-rift and syn-rift sediments in a location

on the OMH (Figs. 3, 5). A prime objective is to constrain the timing of major extension as

recorded within the half-graben systems that formed during the main rifting events. An additional

25

objective is to determine the sedimentary environment, subsidence history and, if possible, the

thermal history during and after breakup.

Fig. 10 Details of Site 3B, 3C (alternate). These sites will sample the Paleogene syn-rift sequence below post-

rift sediments. Site 3B is the optimum site to correlate the cored syn-rift sediments to that of the deep half-

grabens that formed during the major phase of extension. Site 3C is shallower, but stratigraphically less

complete. Sampling of up to 100 meters into basement to characterize its nature will be attempted. The age

and nature of the syn-rift sediments, and of the overlying breakup unconformity (T70, purple ~ 32 Ma) are key

objectives. The depositional environment of the post-rift sequence (T70 – T60) and the margin subsidence

recorded within this are another objectives (note that small-scale faulting in places extends beyond T70). Tg

(green): Basement. T60 (blue): regional basin unconformity (~23 Ma). Ages are inferred by long distance (>

100 km) correlation with industry holes on the inner continental margin. Ages and nature of sediments need

be confirmed here by coring. Unconformity T60 is interpreted to also be present at Site 1148, see main text

for discussion (e.g., section 8, Secondary Objectives).

The site location on the OMH offers an opportunity, within the capability of JOIDES

Resolution, to penetrate to basement while still recovering a representative suite of (syn-rift) half-

graben fill, as well as an overlying sequence of post-rift sediments that can be tied to the deep

26

water Site 1A. These two sites will therefore allow us to piece together a rather comprehensive

record of extension events, and of the associated sedimentary environment to be applied as a

proxy, if not direct indicator for crustal subsidence in time as well as space (i.e., across the

margin). Comparing the age of the syn-rift to post-rift unconformity (‘crustal’ breakup

unconformity) at Site 3B with the final breakup unconformity at Site 1A will allow us to

determine if these are isochronous, or if the ‘breakup unconformity’ in fact is getting younger

towards the COT (Ranero and Perez-Gussinye, 2010; Brune et al., 2014).

Site 3B is planned to penetrate to ‘basement’. This basement might not necessarily be

crystalline basement, but potentially could be pre-rift indurated sediments (Mesozoic?), which in

itself will be interesting and provide constraints on the setting (e.g., level of possible crustal

exhumation, if any) of the margin prior to rifting. Drilling 100 m into ‘basement’ is included in

the operations plan (see section 10). Site 3B is slightly deeper than the alternate 3C, but 3B

nevertheless has first priority because of its potential to recover a more complete record (syn- and

post-rift).

Syn-rift sequences are the only source of information on the margin development in terms of

the timing of (upper) crustal extension, and, combined with the post-rift sediments, the history of

margin subsidence. By combining time markers of crustal rifting with the amount of extension

that can be estimated from the fault pattern, rates of extension can be estimated. The sediment

cores from Site 3B may also provide insights into the development of the thermal regime during

rifting.

These are all important parameters that numerical modeling (e.g., Huismans and Beaumont;

Brune et al., 2014) predicts to significantly differ to characterize the margin development, and are

critical for modeling of the mantle melting regimes in response to passive upwelling of the

asthenospheric mantle during breakup (Perez-Gussinye et al., 2006; Cannat et al., 2009).

7. Potential for Conjugate Margin Drilling

Conjugate margin drilling should be a long-term goal for SCS studies. However, as shown

by our operations plan (see section 10), it will take around 120 days of operations in order to

firmly discriminate between different models of plate rupture. To include the conjugate southern

SCS margin in a first drilling campaign is therefore too ambitious. Furthermore, the distinct

27

asymmetry that may exist during initial breakup (e.g., Fig. 6a) is overprinted, if not disappearing,

as tectonism progresses toward breakup (Pérez-Gussinyé and Reston, 2001; Reston, 2009;

Ranero and Pérez-Gussinyé, 2010). Little may therefore be gained in constraining the margin

model. In fact, more likely a loss may result, if drilling efforts are extended to cover both margins

too early in the investigations (e.g., three drilling legs were conducted on the Galicia-Iberia

margin before its conjugate margin was included for drilling).

Fig.11 Profiles from the Conjugate margin. See main text (Section 7) for discussion.

The conjugate margin to the northern SCS margin segment that we propose to drill is the

Reed Bank or the area just to its east (Hayes and Nissen, 2005; Sun et al., 2009; Fig. 11). The

seismic data quality in this area is far below the dense, state-of-the-art data covering the

conjugate northern SCS margin. Even so, Franke et al. (2011, 2013) reports hyper-extended

margin structures to exist (Fig. 11a). Ding et al. (2013), however, suggest that this margin

experienced sudden necking across a narrow zone (Fig. 11b). The two studies are ~50 km apart.

28

This stresses the need for much better seismic data coverage before pursuing conjugate margin

drilling.

8. Secondary Objectives

Site 1A (Fig. 7) will provide a continuous record of the development of the deep SCS basin

from about early Oligocene time until recent. Site 3B (Fig. 10) is located on the outer margin and

is expected to extend into the Eocene, or perhaps even older. The two sites will provide a seismic

stratigraphically correlated and overlapping sampling of the entire post-rift basin development in

two different basin settings: The outer continental margin and the deep basin. The seismic

stratigraphic correlation can also be extended landward to industry wells (most, but not all data

confidential). Important to note in this regard is that Site 1435 located on completely isolated

structure cannot be seismic stratigraphically tied to regional data. The combination of the

seismically well imaged Sites 1A and 3B will therefore be a major step forward in terms of

understanding regional basin development, and provide much added value to Site 1148 and Site

U1435 cores.

The importance of these new sediment cores in terms of characterizing the tectonic model for

margin formation is previously described. In this section we focus only on the secondary

objective: The SCS basin as recorder of the Cenozoic development of the SE Asia margin.

Asian-Western Pacific Margin without Marginal Seas. One key question in paleo-studies of the

region is the nature of the Asian-Western Pacific margin before rifting within the Paleogene

(Wang, 2004), and the SCS deep basin might yield an answer. Site 3B is located on the outer

margin in a position quite similar to Site 1148, and perhaps also Site U1435 at the outermost

margin (Figs. 2 and 3). It remains unclear whether there was a wide marine basin before the late

Paleogene rifting and eventually sea-floor spreading. Site 1148 recovered deep marine sediments

back to the Early Oligocene. By contrast, industry boreholes have recovered mainly lacustrine

sediment facies further landward on the margin, yet reworked Eocene marine microfossils

occurred frequently in the later marine sequences (Huang et al., 2003). The recent finding at the

outermost margin (Site U1435) of shallow water to perhaps lacustrine sediments of Late Eocene

to Early Oligocene age was not expected. This implies either great lateral variability of

29

sedimentary environment or sudden subsidence within the Early Oligocene. Site 3B will provide

key constraints on the topic of the pre-rifting environment of the SCS.

Environment Reorganization. A geographically widespread unconformity at the Paleogene-

Neogene boundary (~23 Ma) within the SCS basin was recovered at Site 1148. At this site, a

sediment record of about 3 myr was erased within the Late Oligocene with four stratigraphic

hiatuses. The unconformities and slumps near the Oligo–Miocene boundary, and drastic changes

in the provenance of clastic sediments and in microfossil preservation indicate a very unstable

tectonic regime (Li et al., 2003; Li et al., 2005). It is interpreted to coincide with a radical

reorganization of climate patterns in East Asia (Wang, 2004), potentially related to the onset of

the East Asian monsoon (Sun and Wang, 2005) and expansion of deserts in Central Asia (Guo et

al., 2002). It is also roughly contemporary with topographic reversal in China resulting in

formation of the Yangtze River (Wang, 2004; Zheng et al., 2013). However, a direct tie to single

tectonic events is not proven. The available stratigraphic record of this critical time interval is

extremely poor (Wang et al., 2000). Sites 1A and 3B will allow us to recover this section in a

seismic stratigraphically constrained location tied to the wider basin stratigraphy. This should

greatly enhance our chances to understand the timing and nature of regional tectonic and climate

changes as recorded within the sediments of SCS basin.

9. Site Survey Data

The northern SCS continental margin is well surveyed by modern multi-channel seismic

reflection (MCS) data acquired by both industry and academia (Figs. 1, 2). State-of-the-art 2D

MCS data (> 480 channel 6+ km streamer) were collected mainly by CNOOC but made available

for planning purposes. These data allow for truly deep imaging of syn-rift sediments, faulting and

basement structures including base of the crust. Similarly, the Taiwan Integrated Geodynamics

Research (TAIGER) project has conducted extensive studies in the northeastern margin of the

SCS with reflection seismic data of similar high quality and deep crustal imaging (McIntosh et al.,

2012).

All proposed sites are located at or near the intersections of two high-quality MCS lines.

However, in order to avoid areas of faulting or other complexities, not all proposed site locations

are exactly at a crossing point. The proximity of the SCS to the major, marine scientific

30

institutions operating seismic (MCS) research vessels and OBS instruments offers significant

potential for further marine geophysical work along the SCS margins, both before and after

drilling. This has already led to the scheduling in early 2015 of a MCS survey to acquire

supplementary seismic cross lines for all proposed sites prior to safety review.

Swath bathymetry data are available for the entire SCS basin upon request to the Guangzhou

Marine Geological Survey (GMGS), and are included in our site survey data submission. A

detailed magnetic anomaly map of the SCS also exists (Geological Survey of Japan and

Coordinating Committee for Coastal and Offshore Geoscience Programs in East and Southeast

Asia, 1996). Deep crustal and mantle structures in the area have been imaged with surface wave

tomography (Wu et al., 2004).

A time-depth curve from ODP Site 1148 was used for estimating sediment thicknesses in the

SCS (Li et al., 2008) and for planning of Exp. 349. Drilling results from this recent expedition

349 have proven this time-depth function to slightly overestimate drilling depth within the deep

basin by about seven percent. In this proposal we have reduced depth-estimates by five percent

within the deep basins, but maintain the original time-depth conversion for the shallower margin

sites. The detailed operations plan developed by IODP TAMU has used this new, drilling

calibrated time-depth function.

10. Plans for Coring, Logging and Sample Studies

For all the three primary basement sites within the COT (i.e., SCSII-1A, 8A, 9A), IODP

TAMU has developed a detailed operations plan including deployment of re-entry cone and

casing to 800 mbsf (detailed plan is available upon request to TAMU/proponents; summary in

Table I). Highest priority Site 1A is planned with RCB coring all way to basement. This will be

followed by a cautious approach changing to a hard-rock bit for an initial 50 m of basement

penetration, then changing to a new hard-rock bit penetrating another 100 m, and a final, third bit

change to achieve 250 m of basement penetration. Other basement sites are planned to wash

down to ~ 200 m above basement, RCB coring to basement, and changing to a hard-rock drill bit

for 100 m basement penetration.

Site 3B is planned by TAMU with APC to refusal followed by RCB until bit destruction

(operation time estimated on the basis of ~ 100 m basement penetration).

31

Table I: Summary of primary sites with drilling and logging time based on detailed drilling plan prepared by

IODP TAMU*.

Site number

Total depth mbsf

Sediment thickness

Basement penetration

Re-entry

Drilling days

Logging days

Total time On site

Proposal Objectives

3B (3C alt) 1102 1002 m 100 m No 12.5 2.0 14.5 3,4

1A (11A alt)

1638 1388 m 250 m Yes 39.6 3.8 43.4 1,2,3,4

8A (12A alt)

1423 1323 100 m Yes 23.9 1.8 25.7 1,2

9A (13A alt)

1652 1552 100m Yes 22.9 2.0 24.9 1,2

*The total operation time including transits (minor) and port calls is just over 120 days. Time can be

significantly reduced using a Free Fall Funnel instead of re-entry cone at sites (see main text). Re-entry (with

casing) allows for a flexible implementation (see also main text). Proposal objectives 1 through 4 are the

objectives listed in the proposal cover sheet, and in section 2 of the main text.

According to the detailed operations plan by TAMU, the total amount of operation time

(including port call and transit time) is 124 days, i.e., slightly over 120 days (2 x 60 days)

operations. However, if one of the deep-water sites (e.g., 9A), as a contingency, is redesigned to

use a Free Fall Funnel (FFF) instead of re-entry cone (and casing), as much as nine days can be

saved in operations. Obviously, FFF also means increased risk to the hole, but has nevertheless

been successfully applied in the past for multiple re-entries in a hole.

Each drill bit change at basement depth requires close to four days of additional operations

(including the 100 m additional basement penetration). However, the close proximity of the three

basement sites will, with a minimum of transit time, make it possible to initially core say 50 or

150 m into basement, and then, based on drilling results and progress made, subsequently

determine which hole(s) will be the most valuable to deepen further into basement. If scheduled

for drilling, obviously, a final operations plan will include a number of scenarios providing the

science and operations team the maximum flexibility to obtain the high priority goals within the

time available.

We plan to conduct triple combo and FMS logging as deeply as possible. Core orientation of

the basement interval for both structural and paleomagnetic investigations would be desirable.

32

Geochemical studies (whole rock and minerals) will include isotope analysis to determine mantle

source (crystalline rocks) and for provenance studies (sediments). Age dating of basement

igneous rocks will be carried out using the 40

Ar/39

Ar dating techniques. Tectonic tilting and

exhumation history will be addressed through a combination of paleomagnetic studies and

mineral studies to infer P/T closure parameters. Sediments will be examined for geochronology

(magneto- and biostratigraphy), temperature history, and for isotopic compositions to examine

regional and global paleoceanographic changes.

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Site Name: Area or Location:If site is a reoccupation of an old DSDP/ODP Site, Please

include former Site#

IODP Site Summary Forms:

Form 1 – General Site Information

Section A: Proposal Information

Date Form Submitted:

Site Specific Objectives with

Priority(Must include general

objectives in proposal)

List Previous Drilling in Area:

Section B: General Site Information

Latitude:

Distance to Land:

Priority of Site: Water Depth (m):

Longitude:

Coordinate System:

Jurisdiction:Deg:

Deg:

Primary: Alt:

Title of Proposal:

-

(km)

380

SCSII-1A

18.4547167

WGS 84

ODP Leg 184: Asian Monsoon; IODP Exp. 349: South China Sea Tectonics.

Nature of basement: Exhumed serpentinized mantle? Or upper/lower continental crust, or igneousbasement? Time and environment of final breakup, and subsequent subsidence.High priority for proposal objective 1,2,3,4.

Cpp878

no

The north South China Sea basin


yes

116.13167

3715

Page 1 of 2 generated: Mon Oct 13 18:48:12 2014 by if351_pdf (user 0.1713)

Sediments Basement

ProposedPenetration (m):

Total Sediment Thickness (m)

Total Penetration (m):

General Lithologies:

Coring Plan: APC VPC XCB MDCB PCS RCB Re-entry

Wireline LoggingPlan:

Standard Measurements Special Tools

WL Magnetic Susceptibility

LWD Magnetic Field Formation Image(Acoustic)

Porosity Borehole Temperature Formation Fluid Sampling

Density Nuclear Magnetic Resonance

Formation Temperature& Pressure

Gamma Ray Geochemical VSP

Resistivity Side-Wall CoreSampling

Sonic (∆t)

Formation Image (Res)

Check-shot (upon request)

Others:

Max. Borehole Temp.: °C

Mud Logging:(Riser Holes Only)

Cuttings Sampling Intervals

from m to m m intervals


Basic Sampling Intervals:5m

Estimated Days: Drilling/Coring: Logging: Total On-site:

Observatory Plan: Longterm Borehole Observation Plan/Re-entry Plan

Potential Hazards/Weather:

Shallow Gas Complicated Seabed Condition

Hydrothermal Activity

Hydrocarbon Soft Seabed Landslide and Turbidity Current

Shallow Water Flow Currents Gas Hydrate

Abnormal Pressure Fracture Zone Diapir and Mud Volcano

Man-made Objects (e.g., sea-floor cables, dump sites)

Fault High Temperature

H2S High Dip Angle Ice Conditions

CO2 Sensitive marine habitat (e.g., reefs, vents)

Other:

Preferred weather window

Section C: Operational Information

APC

Coring Plan:(Specify or check)

✘

1388

✘

250

✘

Serpentinite/Basalt/upper or lower continentalcrust

1638

✘

✘

✘

3.8

✘

39.6

Not in Monsoonseason (June toOctober)

✘

1388

APC to refusal, RCB to target depth.

✘

✘

Mudstone, siltstone, sandstone


High resolution seismic reflection

IODP Site Summary Forms: Form 2 - Site Survey Detail

Swath bathymetry

Side-looking sonar (surface)

Photography or Video

Heat Flow

Magnetics

Gravity

Other

Water current data

Sediment cores

Ice Conditions

OBS microseismicity

Navigation

Rock sampling

Side-looking sonar (bottom)

Deep Penetrationseismic reflection

Seismic Velocity

Seismic Grid

Refraction (surface)

Refraction (near bottom)

1

2

3

4

5a

5b

6

7

8a

8b

9

10

11a

11b

12

14b14b

15

14a

13

16

17

3.5 kHz

SSP Require-ments *

Existsin DB

* Key to SSP Requirements

X=required; X*=may be required for specific sites; Y=recommended; Y*=may be recommended for specific sites; R=required for re-entry sites; T=required for high temperature environments; † Accurate velocity information is required for holes deeper than 400m.

Location of Site on line (SP or Time only)




Crossing Line(s)

Crossing Line(s)

Primary Line(s)

Primary Line(s)


Proposal #: Site #: Date Form Submitted:

No such data in hand.


Available at ODP Leg 184 and IODP349 sites. Also Piston cores by R/V Vema and R/V Conrad (Damuth, 1980).

no

SCSII-1A

CDP 5532

no

04ec1555

no

CDP 1263

yes Stacking velocity data for 08ec2660 and the stacking velocity image profile for 04ec1555.Sonic velocity from ODP1148.

yesOBS1993 by SCSIO and Tokyo Univerisy (Yan et al., 2001);OBS2006-3 and otherneighbored profiles collected by SCSIO and the SIO(Zhao et al., 2011; Wei et al., 2011).

yes

yes

no

yes

Refraction(surface) Profiler-Sonobuoy measurements by Ludwig et al.( 1979).


Regional compilation by Shi et al. (2003) and Li et al. (2010). Heat flow data are also available from the nearby sites of ODP Leg 184(Wang et al., 2000) and U1432 of IODP349 (Li and Lin et al., 2014).

08ec2660

yes

CNOOC 2004 and 2008 long-cable multi-channel seismic lines.

1' free-air gravity grid (V. 21.1) from Sandwell and Smith (2013).

no

No ice in this region.

878

yes


The data is collected and provided by GMGS.

no

Provided by CNOOC. The original navigation data will upload in the format of linename.p190. The navigation data after stacking were listed in column 2 of relative seg-y files.

yes

no

no

No such data presently.

no

yes

Data grids from Geological Survey of Japan and Coordinating Committee for Coastal and Offshore Geoscience Programmes in East and Southeast Asia (CCOP).

no

Data Type In SSDB SSP Req. Details of available data and data that are still to be collected1a Highresolutionseismicreflection(primary)

Location:

1b Highresolutionseismicreflection(crossing)

Location:

2a Deeppenetrationseismicreflection(primary)

yes 04ec1555

Location: CDP 1263

2b Deeppenetrationseismicreflection(crossing)

yes 08ec2660

Location: CDP 5532

3 SeismicVelocity

yes Stacking velocity data for 08ec2660 and the stacking velocity image profile for04ec1555.Sonic velocity from ODP1148.

4 Seismic Grid yes CNOOC 2004 and 2008 long-cable multi-channel seismic lines.

5a Refraction(surface)

no Refraction(surface) Profiler-Sonobuoy measurements by Ludwig et al.( 1979).

5b Refraction(bottom)

yes OBS1993 by SCSIO and Tokyo Univerisy (Yan et al., 2001);OBS2006-3 and otherneighbored profiles collected by SCSIO and the SIO(Zhao et al., 2011; Wei et al., 2011).

6 3.5 kHz no No such data presently.

7 Swathbathymetry

yes The data is collected and provided by GMGS.

8a Side lookingsonar (surface)

no No such data in hand.

8b Side lookingsonar (bottom)


9 Photographyor video


10 Heat Flow yes Regional compilation by Shi et al. (2003) and Li et al. (2010). Heat flow data are alsoavailable from the nearby sites of ODP Leg 184(Wang et al., 2000) and U1432 ofIODP349 (Li and Lin et al., 2014).

11a Magnetics yes Data grids from Geological Survey of Japan and Coordinating Committee for Coastaland Offshore Geoscience Programmes in East and Southeast Asia (CCOP).

11b Gravity yes 1' free-air gravity grid (V. 21.1) from Sandwell and Smith (2013).

12 Sedimentcores

no Available at ODP Leg 184 and IODP349 sites. Also Piston cores by R/V Vema and R/VConrad (Damuth, 1980).

13 Rocksampling


14a Watercurrent data

no

14b IceConditions

no No ice in this region.

15 OBSmicroseismicity

no

16 Navigation yes Provided by CNOOC. The original navigation data will upload in the format oflinename.p190. The navigation data after stacking were listed in column 2 of relativeseg-y files.

17 Other

Page 1 of 1 - Site Survey Details generated: Mon Oct 13 18:48:17 2014 by if352_t_pdf / kk+w 2007 - 2011 (user 0.4555)

IODP Site Summary Forms: Form 3 – Detailed Logging and Downhole Measurement Plan

Estimated total logging time for this site:

Are high temperatures or other special requirements (e.g., unstable formations), anticipated for logging at this site?

Scientific ObjectiveMeasurement TypeRelevance

(1=high,3=low)

Proposal #:

Water Depth (m):

Site #:

Sed. Penetration (m):


Basement Penetration (m):1388

878 SCSII-1A

3.8

3715 250

Check Shot Survey N/A 0

Nuclear Magnetic Resonance N/A 0

Geochemical N/A 0

Side-wall Core Sample N/A 0

Formation Fluid Sampling N/A 0

Borehole Temperature To constrain the heat flow. 1

Magnetic Susceptibility To know the magnetic properties of relative sediments and rocks 1

Magnetic Field N/A 0

VSP N/A 0

Formation Image (Acoustic) N/A 0

Formation Pressure &Temperature

N/A 0

Other (SET, SETP, ...) N/A 0

Page 1 of 1 - Detailed Logging and Downhole Measurement Plan generated: Mon Oct 13 18:48:19 2014 by if353_t_pdf / kk+w 2007 - 2011 (user 0.2287)

IODP Site Summary Forms: Form 4 – Environmental Protection

1 Summary of Operations at site:

(Example: Triple-APC to refusal, XCB 10 m into basement, log as shown on form 3); include # of holes for APC/XCB, # of temperature deployments)

Based on previous DSDP/ODP/IODP drilling, list all hydrocarbon occurrences of greater than background levels. Give nature of show, age and depth of rock.

From available information, list all commercial drilling in this area that produced or yielded significant hydrocarbon shows. Give depths and ages of hydrocarbon - bearing deposits.

Are there any indications of gas hydrates at this location? Give details.

Are there reasons to expect hydrocarbon accumulations at this site? Please give details.

What “special” precautions need to be taken during drilling?

What abandonment procedures need to be followed:

Please list other natural or manmade hazards which may effect ship's operations:

(e.g. ice, currents, cables)

2

3

4

5

6

7

8

Summary: What do you consider the major risk in drilling at this site?

9


no

no

878

Per IODP standard operating procedure.

No.

APC to refusal, then RCB to target depth or refusal.

None

Sites of ODP Leg 184 and IODP Leg 349 to the north and east have no hydrocarbonoccurrences of greater than background levels.

Weather, not in Monsoon season (June to October)

SCSII-1A

Continuous monitoring under IODP safety standards.

Pollution & Safety Hazard Comment1. Summary of Operations at site. APC to refusal, then RCB to target depth or refusal.

2. All hydrocarbon occurrencesbased on previous DSDP/ODP/IODPdrilling.

Sites of ODP Leg 184 and IODP Leg 349 to the north and east have no hydrocarbonoccurrences of greater than background levels.

3. All commercial drilling in this areathat produced or yielded significanthydrocarbon shows.

No.

4. Indications of gas hydrates at thislocation.

no

5. Are there reasons to expecthydrocarbon accumulations at thissite?

no

6. What "special" precautions will betaken during drilling?


7. What abandonment proceduresneed to be followed?


8. Natural or manmade hazards whichmay effect ship's operations.

None

9. Summary: What do you considerthe major risks in drilling at this site?

Weather, not in Monsoon season (June to October)

Page 1 of 1 - Environmental Protection generated: Mon Oct 13 18:48:21 2014 by if354_t_pdf / kk+w 2007 - 2011 (user 0.3173)

IODP Site Summary Forms: Form 5 – Lithologies

Key reflectors, Unconformities,

faults, etc

Age Assumed velocity (km/sec)

Lithology Paleo-environment Avg. rate of sed. accum. (m/My)

Comments

-

Subbottom depth (m)

Proposal #: Site #: Date Form Subm.:878 2014-10-01 15:39:38SCSII-1ACpp

0-1260 Top Oligocene 0-23 1.9 Siltstone andsandstone

Deep marine 58 Ages and lithology areestimated from publisheddata, and from correlations ofseismic facies.

1260-1331 Top basement (ROU) 23-32 2.0 Siltstone andsandstone

Shallow to deepmarine

14 Sedimentary rates are onlyvery rough estimates.

1331-1431 >32Ma 4.0 Basalt or serpentinite Serpentinized mantle,or upper/lowercontinental crust, origneous

Page 1 of 1 generated: Mon Oct 13 18:48:23 2014 by if355_pdf / kk+w 2007 - 2011 (user 0.4178)



faults, etc



Comments

-

Subbottom depth (m)


Form 6 - Site Summary Figure

Site SummaryFigure Comment

Page 1 of 1 - Site Summary Figure generated: Mon Oct 13 18:48:26 2014 by if356_pdf / kk+w 2007 - 2012 (user 0.3268)

Site SCSII-1A

Fig.1 Location of Site SCSII-1A (indicated by CDP number) and

two related seismic profiles on bathymetry

Fig.2 The original (up) and interpreted (down) primary line (04ec1555) and

cross line (08ec2660) of site SCSII-1A












Latitude:

Distance to Land:


Longitude:

Coordinate System:

Jurisdiction:Deg:

Deg:

Primary: Alt:

Title of Proposal:

-

(km)

330

SCSII-3B

18.93037

WGS 84

ODP Leg 184: Asian Monsoon; IODP Exp. 349: South China Sea Tectonics.

Recover syn-rift and post-rift sedimentsTo constrain age, duration and environment of rifting and breakup. Subsidence historyHigh priority for proposal objectives 3,4.

Cpp878

no



yes

115.85142

2928


Sediments Basement















Sonic (∆t)



Others:



















Other:



APC


✘

1002

100

✘

Siltstone, sandstone or upper crustal rocks

1102

✘

✘

✘

2.0

✘

12.5

Not in monsoonseason (June toOctober).

✘

1002


✘

✘





Swath bathymetry



Heat Flow

Magnetics

Gravity

Other

Water current data

Sediment cores

Ice Conditions

OBS microseismicity

Navigation

Rock sampling



Seismic Velocity

Seismic Grid



1

2

3

4

5a

5b

6

7

8a

8b

9

10

11a

11b

12

14b14b

15

14a

13

16

17

3.5 kHz

SSP Require-ments *

Existsin DB







Crossing Line(s)

Crossing Line(s)

Primary Line(s)

Primary Line(s)



None

None

Available at ODP Leg 184 and IODP349 sites. Also Piston cores by R/V Vema and R/V Conrad(Damuth, 1980).

no

SCSII-3B

CDP 3462

no

04ec1555

no

CDP 6090

yes Stacking velocity data for 05kmg2590 and an image profile for the stacking velocity of 05ec1530. Sonic velocity from ODP1148.


yes

yes

no

yes

Refraction(surface) Profiler-Sonobuoy measurements by Ludwig et al.( 1979)


05kmg2590

yes



no


878

yes

None


no

Provided by CNOOC. The original navigation data will be uploaded in the format of linename.p190. The navigation data after stacking were listed in column 2 of related seg-y files.

yes

no

no

no

yes


no


Location:


Location:


yes 04ec1555

Location: CDP 6090


yes 05kmg2590

Location: CDP 3462

3 SeismicVelocity

yes Stacking velocity data for 05kmg2590 and an image profile for the stacking velocity of05ec1530. Sonic velocity from ODP1148.



no Refraction(surface) Profiler-Sonobuoy measurements by Ludwig et al.( 1979)



6 3.5 kHz no

7 Swathbathymetry



no


no


no




12 Sedimentcores

no Available at ODP Leg 184 and IODP349 sites. Also Piston cores by R/V Vema and R/VConrad(Damuth, 1980).

13 Rocksampling

no None


no None

14b IceConditions



no None

16 Navigation yes Provided by CNOOC. The original navigation data will be uploaded in the format oflinename.p190. The navigation data after stacking were listed in column 2 of relatedseg-y files.

17 Other






(1=high,3=low)

Proposal #:

Water Depth (m):

Site #:




878 SCSII-3B

2.0

2928 100



Geochemical N/A 0






VSP N/A 0



N/A 0














2

3

4

5

6

7

8


9


N/A

N/A

878


N/A

APC to refusal, RCB to target depth. Log as shown on form 3.

No hydrocarbon occurrences of greater than background levels from ODP leg 184.

Weather, such as the Monsoon and typhon.

SCSII-3B


Pollution & Safety Hazard Comment1. Summary of Operations at site. APC to refusal, RCB to target depth. Log as shown on form 3.




N/A


N/A


N/A











faults, etc



Comments

-

Subbottom depth (m)

Proposal #: Site #: Date Form Subm.:878 2014-10-01 15:31:46SCSII-3BCpp



17 Ages and lithology areestimated from publisheddata, and from correlations ofseismic facies.

430-1002 Top basement(ROU) 23-45 2.3 Siltstone andsandstone

Lacustrine to marine 23 Sedimentary rates are onlyvery rough estimates

1002-1102 >45 4.0 Sandstone, or uppercrustal rocks

Basement rocks




faults, etc



Comments

-

Subbottom depth (m)

Proposal #: Site #: Date Form Subm.:878 2014-10-01 15:31:46SCSII-3BCpp




Site summary Form 6

Site SCSII-3B

Fig.1 Location of Site SCSII-3B (indicated by CDP number)

and two related seismic profiles on bathymetry

Fig.2 The original (up) and interpreted (down) primary line (04ec1555) and cross line

(05kmg2590) of site SCSII-3B












Latitude:

Distance to Land:


Longitude:

Coordinate System:

Jurisdiction:Deg:

Deg:

Primary: Alt:

Title of Proposal:

-

(km)

340

SCSII-3C

18.86948

WGS 84

ODP Leg 184, IODP Exp. 349: South China Sea Tectonics

Recover syn-rift and post-rift sedimentsTo constrain age, duration and environment of rifting and breakup. Subsidence historyAlternate to 3B. High priority for proposal objective 3, 4.

Cpp878

no



no

115.88742

2910


Sediments Basement















Sonic (∆t)



Others:



















Other:



APC


✘

743

100

✘

Mesozoic granites or sedimentary/metamorphicrocks.

843

✘

✘

✘

1.5

✘

11.5

no

Not in monsoonseason(June toOctober).

✘

743

✘

✘

Mudstone, siltstone, sandstone.




Swath bathymetry



Heat Flow

Magnetics

Gravity

Other

Water current data

Sediment cores

Ice Conditions

OBS microseismicity

Navigation

Rock sampling



Seismic Velocity

Seismic Grid



1

2

3

4

5a

5b

6

7

8a

8b

9

10

11a

11b

12

14b14b

15

14a

13

16

17

3.5 kHz

SSP Require-ments *

Existsin DB







Crossing Line(s)

Crossing Line(s)

Primary Line(s)

Primary Line(s)




no

SCSII-3C

CDP 5110

no

04ec1555

no

CDP 5472

yes Stacking velocity data for 08ec2606a and an image profile for the stacking velocity of 04ec1555. Sonic velocity from ODP1148.


yes

yes

no

yes



08ec2606a

yes



no


878

yes


no


yes

no

no

None

no

yes


no


Location:


Location:


yes 04ec1555

Location: CDP 5472


yes 08ec2606a

Location: CDP 5110

3 SeismicVelocity

yes Stacking velocity data for 08ec2606a and an image profile for the stacking velocity of04ec1555. Sonic velocity from ODP1148.






6 3.5 kHz no None

7 Swathbathymetry



no


no


no




12 Sedimentcores


13 Rocksampling

no


no

14b IceConditions



no


17 Other






(1=high,3=low)

Proposal #:

Water Depth (m):

Site #:




878 SCSII-3C

1.5

2910 100



Geochemical N/A 0






VSP N/A 0



N/A 0

Other (SET, SETP, ...) 0













2

3

4

5

6

7

8


9


none

none

878


none


none

ODP Leg 184 reveals no hydrocarbon occurrences greater than background levels.


SCSII-3C




ODP Leg 184 reveals no hydrocarbon occurrences greater than background levels.


none


none


none






none






faults, etc



Comments

-

Subbottom depth (m)

Proposal #: Site #: Date Form Subm.:878 2014-10-01 15:22:08SCSII-3CCpp

0-322 Top Oligocene 0-23 1.6 Siltstone,sandstone, andcarbonate


13 Ages and lithology areestimated fromcorrelations of seismicfacies.

322-742 Top basement 23-45 2.0 Siltstone andsandstone

coastal planand/or delta front

21 Sedimentary rates areonly very roughestimates.

742-842 >45 2.0 Igneous ormetamorphicrocks

basement




faults, etc



Comments

-

Subbottom depth (m)

Proposal #: Site #: Date Form Subm.:878 2014-10-01 15:22:08SCSII-3CCpp




Site summary Form 6

Site SCSII-3C

Fig.1 Location of Site SCSII-3C (indicated by CDP number) and

two related seismic profiles on bathymetry


cross line (08ec2606a) of site SCSII-3C












Latitude:

Distance to Land:


Longitude:

Coordinate System:

Jurisdiction:Deg:

Deg:

Primary: Alt:

Title of Proposal:

-

(km)

400

SCSII-8A

18.27145

WGS 84

ODP Leg 184: Asian Monsoon, IODP Exp. 349: South China Sea Tectonics

Nature of basement: Exhumed serpentinized mantle, or igneous ocean crust. Paleodepth and initialsubsidence of the very earliest SCS ocean basin.High priority for proposal objective 1,2.

Cpp878

no



yes

116.23985

3801


Sediments Basement















Sonic (∆t)



Others:



















Other:



APC


✘

1323

✘

100

✘

Serpentinite or basalt

~120°C

1423

✘

✘

✘

1.8

✘

23.9


✘

1323

RCB from 200m above basement till target depth

✘

✘





Swath bathymetry



Heat Flow

Magnetics

Gravity

Other

Water current data

Sediment cores

Ice Conditions

OBS microseismicity

Navigation

Rock sampling



Seismic Velocity

Seismic Grid



1

2

3

4

5a

5b

6

7

8a

8b

9

10

11a

11b

12

14b14b

15

14a

13

16

17

3.5 kHz

SSP Require-ments *

Existsin DB







Crossing Line(s)

Crossing Line(s)

Primary Line(s)

Primary Line(s)



None

None

Available at ODP Leg 184 and IODP349 sites. Also Piston cores by R/V Vema and R/V Conrad (Damuth, 1980).

no

SCSII-8A

CDP: 23049

no

08ec1555

no

CDP: 5744

yes Stacking velocity data for both 08ec1555 and 08ec2678 will be uploaded. Sonic velocity from ODP1148.


yes

yes

no

yes

Refraction(surface) Profiler-Sonobuoy measurements by Ludwig et al.(1979)


08ec2678

yes


1' free-air gravity grid (V. 21.1) from Sandwell and Smith (2013)

no

No ice in this region

878

yes

None

no


no


yes

no

no

None

no

yes


no


Location:


Location:


yes 08ec1555

Location: CDP: 5744


yes 08ec2678

Location: CDP: 23049

3 SeismicVelocity

yes Stacking velocity data for both 08ec1555 and 08ec2678 will be uploaded. Sonic velocityfrom ODP1148.



no Refraction(surface) Profiler-Sonobuoy measurements by Ludwig et al.(1979)



6 3.5 kHz no None

7 Swathbathymetry



no


no


no



11b Gravity yes 1' free-air gravity grid (V. 21.1) from Sandwell and Smith (2013)

12 Sedimentcores

no Available at ODP Leg 184 and IODP349 sites. Also Piston cores by R/V Vema and R/VConrad (Damuth, 1980).

13 Rocksampling

no None


no None

14b IceConditions

no No ice in this region


no None


17 Other no






(1=high,3=low)

Proposal #:

Water Depth (m):

Site #:




878 SCSII-8A

1.8

3801 100



Geochemical N/A 0






VSP N/A 0



N/A 0














2

3

4

5

6

7

8


9


No

No

878


N/A

RCB from 200m above basement till target depth. Log as shown on form 3.

Sites of ODP Leg 184 and IODP 349 have no hydrocarbon occurrences of greater thanbackground levels


SCSII-8A


Pollution & Safety Hazard Comment1. Summary of Operations at site. RCB from 200m above basement till target depth. Log as shown on form 3.


Sites of ODP Leg 184 and IODP 349 have no hydrocarbon occurrences of greater thanbackground levels


N/A


No


No











faults, etc



Comments

-

Subbottom depth (m)




63 Ages and lithology areestimated from publisheddata, and from correlations ofseismic facies

1240-1323 Top basement ~23-32 2.0 Siltstone andsandstone

Lacustrine to shallowmarine

28 Sedimentary rates are onlyvery rough estimates.

1323-1423 32Ma orolder

4.0 Serpentinizedperidotite, basalt

Basement with COT Serpentinized peridotite,basalt




faults, etc



Comments

-

Subbottom depth (m)





Site summary Form 6

Site SCSII-8A

Fig.1 Location of Site SCSII-8A (indicated by CDP number)

and two related seismic profiles on bathymetry

Fig.2 The original (up) and interpreted (down) primary line (08ec1555) and cross

line (08ec2678) of site SCSII-8A












Latitude:

Distance to Land:


Longitude:

Coordinate System:

Jurisdiction:Deg:

Deg:

Primary: Alt:

Title of Proposal:

-

(km)

420

SCSII-9A

18.14346

WGS 84


Nature of oceanic crust: Was a robust mantle-melting regime established shortly after breakup or not?High priority for objectives 2,1.

Cpp878

no



yes

116.31445

3864


Sediments Basement















Sonic (∆t)



Others:



















Other:



APC


✘

1552

✘

100

✘


~120°C

1652

✘

✘

✘

2.0

✘

22.9

N/A

Not in Monsoonseason (June toOctober).

✘

1552

RCB from 200m above basement till target depth

✘

✘





Swath bathymetry



Heat Flow

Magnetics

Gravity

Other

Water current data

Sediment cores

Ice Conditions

OBS microseismicity

Navigation

Rock sampling



Seismic Velocity

Seismic Grid



1

2

3

4

5a

5b

6

7

8a

8b

9

10

11a

11b

12

14b14b

15

14a

13

16

17

3.5 kHz

SSP Require-ments *

Existsin DB







Crossing Line(s)

Crossing Line(s)

Primary Line(s)

Primary Line(s)



None


no

SCSII-9A

CDP 4088

no

08ec2696

no

CDP 4700

yes Stacking velocities for both 08ec2696 and 08ec1555 will be uploaded. Sonic velocity from ODP1148.

yesOBS1993 by SCSIO and Tokyo Univerisy (Yan et al., 2001);OBS2006-3 and otherneighbored profiles collected by SCSIO and the SIO (Zhao et al., 2011; Wei et al., 2011).

yes

yes

no

yes

Refraction(surface) Profiler-Sonobuoy measurements by Ludwig et al.( 1979).

None


08ec1555

yes


1’ free-air gravity grid (V. 21.1) from Sandwell and Smith (1997).

no


878

yes

None


no


yes

no

no

None

no

yes


no


Location:


Location:


yes 08ec2696

Location: CDP 4700


yes 08ec1555

Location: CDP 4088

3 SeismicVelocity

yes Stacking velocities for both 08ec2696 and 08ec1555 will be uploaded. Sonic velocityfrom ODP1148.



no Refraction(surface) Profiler-Sonobuoy measurements by Ludwig et al.( 1979).


yes OBS1993 by SCSIO and Tokyo Univerisy (Yan et al., 2001);OBS2006-3 and otherneighbored profiles collected by SCSIO and the SIO (Zhao et al., 2011; Wei et al., 2011).

6 3.5 kHz no None

7 Swathbathymetry



no None


no None


no None



11b Gravity yes 1’ free-air gravity grid (V. 21.1) from Sandwell and Smith (1997).

12 Sedimentcores


13 Rocksampling

no


no

14b IceConditions



no


17 Other






(1=high,3=low)

Proposal #:

Water Depth (m):

Site #:




878 SCSII-9A

2.0

3864 100



Geochemical N/A 0






VSP N/A 0



N/A 0














2

3

4

5

6

7

8


9


N/A

No

878

Per IODP standard operating procedure

N/A

RCB from 200m above basement till target depth.

Not in this area.


SCSII-9A


Pollution & Safety Hazard Comment1. Summary of Operations at site. RCB from 200m above basement till target depth.


Not in this area.


N/A


N/A


No




Per IODP standard operating procedure







faults, etc



Comments

-

Subbottom depth (m)


0-1251 Top Oligocene 0-23 2 Siltstone and sandstone Deep marine 50

1251-1552 Top Basement 23-32 2.3 Mudstone, siltstone, sandstone all possible Deep marine 43

1552-1652 <32 4.5 Serpentinite, or basalt basement




faults, etc



Comments

-

Subbottom depth (m)





Site summary Form 6

Site SCSII-9A

Fig.1 Location of Site SCSII-9A (indicated by CDP

number) and two related seismic profiles on bathymetry

Fig.2 The original (up) and interpreted (down) primary line (08ec2696) and cross

line (08ec1555) of site SCSII-9A












Latitude:

Distance to Land:


Longitude:

Coordinate System:

Jurisdiction:Deg:

Deg:

Primary: Alt:

Title of Proposal:

-

(km)

420

SCSII-13A

18.10495

WGS 84


Nature of oceanic crust: Was a robust mantle-melting regime established shortly after breakup or not.Alternate to 9A. High priority for proposal objectives 2, 1.

Cpp878

No



no

116.06523

3841


Sediments Basement















Sonic (∆t)



Others:



















Other:



APC


✘

1776

✘

100

✘

Serpentinite or basalt.

~120

1876

✘

✘

✘

3.8

✘

24

Re-entry Plan


✘

1776

RCB from 200m above basement till target depth.

✘

✘





Swath bathymetry



Heat Flow

Magnetics

Gravity

Other

Water current data

Sediment cores

Ice Conditions

OBS microseismicity

Navigation

Rock sampling



Seismic Velocity

Seismic Grid



1

2

3

4

5a

5b

6

7

8a

8b

9

10

11a

11b

12

14b14b

15

14a

13

16

17

3.5 kHz

SSP Require-ments *

Existsin DB







Crossing Line(s)

Crossing Line(s)

Primary Line(s)

Primary Line(s)



N/A

N/A

None

Available at ODP Leg 184 and 349 sites. Also Piston cores by R/V Vema and R/V Conrad (Damuth, 1980).

no

SCSII-13A

CDP 21040

no

08ec1530

no

CDP 1041

yes Stacking velocity data for both 08ec1530 and 08ec2678 will be uploaded.The time-Depth conversion is according to Li et al.,2008.

yesOBS1993 by SCSIO and Tokyo Univerisy (Yan et al., 2001);OBS2006-3 and otherneighbored profiles collected by SCSIO and SIO (Zhao et al., 2011; Wei et al., 2011).

yes

yes

no

yes

Provided by CNOOC. The original navigation data will be uploaded in the format oflinename.p190. The navigation data after stacking were listed in column 2 of related seg-yfiles.


None


08ec2678

yes


1’ free-air gravity grid (V. 21.1) from Sandwell and Smith (1997).

no


878

yes

None

None

no


no

Seismic data is accurately navigated/logged.

yes

no

no

none

no

yes


no


Location:


Location:


yes 08ec1530

Location: CDP 1041


yes 08ec2678

Location: CDP 21040

3 SeismicVelocity

yes Stacking velocity data for both 08ec1530 and 08ec2678 will be uploaded.The time-Depthconversion is according to Li et al.,2008.





yes OBS1993 by SCSIO and Tokyo Univerisy (Yan et al., 2001);OBS2006-3 and otherneighbored profiles collected by SCSIO and SIO (Zhao et al., 2011; Wei et al., 2011).

6 3.5 kHz no none

7 Swathbathymetry



no None


no None


no None



11b Gravity yes 1’ free-air gravity grid (V. 21.1) from Sandwell and Smith (1997).

12 Sedimentcores

no Available at ODP Leg 184 and 349 sites. Also Piston cores by R/V Vema and R/VConrad (Damuth, 1980).

13 Rocksampling

no N/A


no N/A

14b IceConditions



no None

16 Navigation yes Seismic data is accurately navigated/logged.

17 Other no Provided by CNOOC. The original navigation data will be uploaded in the format oflinename.p190. The navigation data after stacking were listed in column 2 of relatedseg-y files.






(1=high,3=low)

Proposal #:

Water Depth (m):

Site #:




878 SCSII-13A

3.8

3841 100



Geochemical N/A 0






VSP N/A 0



N/A 0














2

3

4

5

6

7

8


9


No

No

878


N/A

RCB from 200m above basement to target depth.



SCSII-13A


Pollution & Safety Hazard Comment1. Summary of Operations at site. RCB from 200m above basement to target depth.




N/A


No


No











faults, etc



Comments

-

Subbottom depth (m)


0-1251 Top Oligocene 0-23 1.8 Siltstone and sandstone Deep marine 50

1251-1776 Top Basement 23-32 2.2 Mudstone, siltstone, sandstone allpossible

Siltstone and sandstone 86

1776-1876 4.5 Serpentinite, or basalt Serpentinized mantle, or igneous oceancrust

N/A




faults, etc



Comments

-

Subbottom depth (m)




Site summary Form 6 for Site SCS II-13A.


Site summary Form 6

Site SCSII-13A
















Latitude:

Distance to Land:


Longitude:

Coordinate System:

Jurisdiction:Deg:

Deg:

Primary: Alt:

Title of Proposal:

-

(km)

389

SCSII-12A

18.27419

WGS 84

ODP Leg 184: Asian Monsoon IODP Exp. 349: South China Sea Tectonics

Nature of basement: exhumed serpentinized mantle, or igneous ocean crust. Paleodepth and initialsubsidence of the very earliest SCS ocean basin.Alternate to 8A. High priority for proposal objective 1,2.

Cpp878

no

The northern margin of the SouthChina Sea


no

115.96566

3781


Sediments Basement















Sonic (∆t)



Others:



















Other:



APC


✘

1826

✘

100

✘


~120

1926

✘

✘

✘

4

✘

24.3


✘

1826

RCB from 200 m above basement till target

✘

✘





Swath bathymetry



Heat Flow

Magnetics

Gravity

Other

Water current data

Sediment cores

Ice Conditions

OBS microseismicity

Navigation

Rock sampling



Seismic Velocity

Seismic Grid



1

2

3

4

5a

5b

6

7

8a

8b

9

10

11a

11b

12

14b14b

15

14a

13

16

17

3.5 kHz

SSP Require-ments *

Existsin DB







Crossing Line(s)

Crossing Line(s)

Primary Line(s)

Primary Line(s)



None.

None.

None


no

SCSII-12A

CDP: 7072

no

04ec1530

no

CDP: 11103

yes Stacking velocity data for 08ec2660 and an image profile for the stacking velocity of 04ec1530. Sonic velocity from ODP1148.


yes

yes

no

yes

Refraction(surface) Profiler-Sonobuoy measurements by Ludwig et al.(1979)

None


08ec2660

yes



no


878

yes

None

None


no


yes

no

no

None

no

yes


no


Location:


Location:


yes 04ec1530

Location: CDP: 11103


yes 08ec2660

Location: CDP: 7072

3 SeismicVelocity

yes Stacking velocity data for 08ec2660 and an image profile for the stacking velocity of04ec1530. Sonic velocity from ODP1148.



no Refraction(surface) Profiler-Sonobuoy measurements by Ludwig et al.(1979)



6 3.5 kHz no None

7 Swathbathymetry



no None


no None


no None




12 Sedimentcores


13 Rocksampling

no None.


no None.

14b IceConditions



no None


17 Other






(1=high,3=low)

Proposal #:

Water Depth (m):

Site #:




878 SCSII-12A

4

3781 100

Check Shot Survey n/a 0


Geochemical N/A 0






VSP N/A 0



N/A 0














2

3

4

5

6

7

8


9


No

N/A

878


N/A

RCB from 200m above basement to target depth. Log as shown on form 3.

None known

N/A


SCSII-12A


Pollution & Safety Hazard Comment1. Summary of Operations at site. RCB from 200m above basement to target depth. Log as shown on form 3.


N/A


N/A


No


N/A






None known






faults, etc



Comments

-

Subbottom depth (m)


0-1665 Top Oligocene 0-23 2.1 Siltstone and sandstone Deep marine 70 Supposed to be loose to weakconsolidated.

1665-1826 Top basment 23-32 2.5 Siltstone and sandstone Deep to shallow marine 23 Might be intermediatelyconsolidated.

1826-1926 Basement >32 4.5 Serpentinized peridotiteor basalt

basement




faults, etc



Comments

-

Subbottom depth (m)






Site summary Form 6

Site SCSII-12A
















Latitude:

Distance to Land:


Longitude:

Coordinate System:

Jurisdiction:Deg:

Deg:

Primary: Alt:

Title of Proposal:

-

(km)

370

SCSII-11A

18.41089

WGS 84

ODP Leg 184: Asian Monsoon IODP Exp. 349: South China Sea Tectonics

Nature of basement:exhumed serpentinized mantle? Or upper/lower continental crust, or igneousbasement? Time and environment of final breakup, and subsequent subsidence.Alternate to 1A. High priority for objectives 1,2,3,4.

Cpp878

no

The northern South China Sea


no

115.88519

3739


Sediments Basement















Sonic (∆t)



Others:



















Other:



APC


✘

1265

✘

100

✘

Serpentinite/ Igneous/upper or lower continentalcrust

1365

✘

✘

✘

1.8

✘

39


✘

1265


✘

✘





Swath bathymetry



Heat Flow

Magnetics

Gravity

Other

Water current data

Sediment cores

Ice Conditions

OBS microseismicity

Navigation

Rock sampling



Seismic Velocity

Seismic Grid



1

2

3

4

5a

5b

6

7

8a

8b

9

10

11a

11b

12

14b14b

15

14a

13

16

17

3.5 kHz

SSP Require-ments *

Existsin DB







Crossing Line(s)

Crossing Line(s)

Primary Line(s)

Primary Line(s)



None

None

Piston cores by R/V Vema and R/V Conrad (Damuth, 1980)

no

SCSII-11A

CDP: 3163

no

04ec1530

no

CDP: 9712

yes No stacking velocity data for 08ec2639 or 04ec1530. But an image profile for the stacking velocity will be uploaded for 04ec1530. Sonic velocity from ODP1148.

yesOBS1993 by SCSIO and Tokyo Univerisy (Yan et al., 2001);OBS2006-3 and otherneighbored profiles collected by SCSIO and SIO(Zhao et al., 2011; Wei et al., 2011).

yes

yes

no

yes

Two stages of Sino-US cooperation in the early 1980s that have sonobuoy measurements and two ship expanding spread profile nearby (Nissen et al., 1995).

None


08ec2639

yes


1’ free-air gravity grid (V. 21.1) from Sandwell and Smith (2013)

no


878

yes

None

None


no


yes

no

no

None

no

yes


no


Location:


Location:


yes 04ec1530

Location: CDP: 9712


yes 08ec2639

Location: CDP: 3163

3 SeismicVelocity

yes No stacking velocity data for 08ec2639 or 04ec1530. But an image profile for thestacking velocity will be uploaded for 04ec1530. Sonic velocity from ODP1148.



no Two stages of Sino-US cooperation in the early 1980s that have sonobuoymeasurements and two ship expanding spread profile nearby (Nissen et al., 1995).


yes OBS1993 by SCSIO and Tokyo Univerisy (Yan et al., 2001);OBS2006-3 and otherneighbored profiles collected by SCSIO and SIO(Zhao et al., 2011; Wei et al., 2011).

6 3.5 kHz no None

7 Swathbathymetry



no None


no None


no None



11b Gravity yes 1’ free-air gravity grid (V. 21.1) from Sandwell and Smith (2013)

12 Sedimentcores

no Piston cores by R/V Vema and R/V Conrad (Damuth, 1980)

13 Rocksampling

no None


no

14b IceConditions



no None


17 Other






(1=high,3=low)

Proposal #:

Water Depth (m):

Site #:




878 SCSII-11A

1.8

3739 100



Geochemical N/A 0






VSP N/A 0



N/A 0














2

3

4

5

6

7

8


9


No

No

878


N/A


ODP Leg 184 and IODP349 showed hydrocarbon occurrences no greater than backgroundlevels.


SCSII-11A




ODP Leg 184 and IODP349 showed hydrocarbon occurrences no greater than backgroundlevels.


N/A


No


No











faults, etc



Comments

-

Subbottom depth (m)


0-1265 Top basement 0-32 2 Clay, siltstone,sandstone

Deep marine 50 Ages and lithology areestimated from correlations ofseismic facies.

1265-1365 32 or older 4.5 Siltstone, igneous ormetamorphic rocks, orserpentinite


50




faults, etc



Comments

-

Subbottom depth (m)






Site summary Form 6

Site SCSII-11A





878 Cpp - J-DESCj-desc.org/jpn/wp-content/uploads/2015/10/878-CPP.pdf · South China Sea Institute...

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