The Origin of m Langes Cautionary Tales From Indonesia 2013 Journal of Asian Earth Sciences

8/16/2019 The Origin of m Langes Cautionary Tales From Indonesia 2013 Journal of Asian Earth Sciences

1/11

The origin of mélanges: Cautionary tales from Indonesia

A.J. Barber ⇑

Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK

a r t i c l e i n f o

Article history:

Available online 8 January 2013

Keywords:

Mélange

Mud diapirs

Mud volcanoes

Timor

Sumba

Nias

a b s t r a c t

The origin of block-in-matrix mélanges has been the subject of intense speculation by structural and tec-

tonic geologists working in accretionary complexes since their first recognition in the early twentieth

century. Because of their enigmatic nature, a number of important international meetings and a largenumber of publications have been devoted to the problem of the origin of mélanges. As mélanges show

the effects of the disruption of lithological units to form separate blocks, and also apparently show the

effects shearing in the scaly fabric of the matrix, a tectonic origin has often been preferred. Then it

was suggested that the disruption to form the blocks in mélanges could also occur in a sedimentary envi-

ronment due to the collapse of submarine fault scarps to form olistostromes, upon which deformation

could be superimposed tectonically. Subsequently it has proposed that some mélanges have originated

by overpressured clays rising buoyantly towards the surface, incorporating blocks of the overlying rocks

in mud or shale diapirs and mud volcanoes.

Two well-known examples of mélanges from the Banda and Sunda arcs are described, to which tectonic

and sedimentary origins were confidently ascribed, which proved on subsequent examination to have

been formed due to mud diapirism, in a dynamically active environment, as the result of tectonism only

indirectly. Evidence from the Australian continental Shelf to the south of Sumba shows that large quan-

tities of diapiric mélange were generated before the diapirs were incorporated in the accretionary com-

plex. Comparable diapirs can be recognised in Timor accreted at an earlier stage. Evidence from both

Timor and Nias shows that diapiric mélange can be generated well after the initial accretion process

was completed.The problem is: Why, when diapirism is so abundantly found in present convergent margins, is it so

rarely reported from older orogenic belts? Many occurrences of mélanges throughout the world to which

tectonic and/or sedimentary and origins have been ascribed, may in future investigations prove to have

had a diapiric origin.

It is emphasised that although the examples of diapiric mélange described here may contain ophiolitic

blocks, they were developed in shelf or continental margin environments, and do not contain blocks of

high grade metamorphic rocks in a serpentinous matrix; such mélanges originate diapirically during sub-

duction in a mantle environment, as previous authors have suggested.

2013 Elsevier Ltd. All rights reserved.

1. Introduction

When Greenly (1919) described a chaotic unit in the GwnaGroup of Anglesey as ‘mélange’, containing a variety of blocks of

ocean floor and continental shelf materials, such as spilitic pillow

lava and tuff, red jasper chert, manganiferous limestone, shale,

quartzite and grey limestone in a fine-grained matrix, it seemed

obvious that this mélange had been disrupted and sheared during

a process of tectonic deformation. Later Beneo (1955) described

extensive deposits of mélange in Sicily in the western Mediterra-

nean, which he interpreted as having been formed in a sedimen-

tary environment as the product of large-scale submarine

landslides. This interpretation has been used frequently to account

for the large-scale mélanges of the Argille Scagliose throughout

Italy. In the discussion following Beneo’s (1955) paper, Floresintroduced the terms olistostrome for these deposits, and olistoliths

for the included blocks. Although Hsü (1968, 1974) recognised tec-

tonic and olistostromal mélanges he suggested that the term

‘mélange’ should be restricted to those formed tectonically, in

practice, due to the difficulty of determining their origins, the term

has been used to describe all ‘block in matrix’ mélange deposits

worldwide, however they may have originated.

Subsequently both tectonic and sedimentary interpretations,

sometimes in combination, have been offered for many other

occurrences, especially where mélanges are found in association

with accretionary complexes, formed in subduction trenches from

oceanic material scraped off downgoing oceanic plates (e.g. Aalto,

1367-9120/$ - see front matter 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.jseaes.2012.12.021

⇑ Tel.: +44 020 7228 1897.

E-mail address: [email protected]

Journal of Asian Earth Sciences 76 (2013) 428–438

Contents lists available at SciVerse ScienceDirect

Journal of Asian Earth Sciences

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j s e a e s

http://dx.doi.org/10.1016/j.jseaes.2012.12.021mailto:[email protected]://dx.doi.org/10.1016/j.jseaes.2012.12.021http://www.sciencedirect.com/science/journal/13679120http://www.elsevier.com/locate/jseaeshttp://www.elsevier.com/locate/jseaeshttp://www.sciencedirect.com/science/journal/13679120http://dx.doi.org/10.1016/j.jseaes.2012.12.021mailto:[email protected]://dx.doi.org/10.1016/j.jseaes.2012.12.021http://crossmark.crossref.org/dialog/?doi=10.1016/j.jseaes.2012.12.021&domain=pdf


2/11

1981; Cowan, 1985; Collins and Robertson, 1997; Ogawa, 1998;

Robertson and Pickett, 2000; Robertson and Ustaömer, 2011).

Meanwhile, geologists using seismic reflection profiling and dril-

ling for oil in deltaic deposits, frequently encountered salt diapirs

and shale diapirs containing block-in-matrix deposits in deltas on

passive margins, attributed to the mobilisation of salt and shale

units due to overpressure generated in areas with very high sedi-

mentation rates, e.g. Nile Delta (Loncke et al., 2006), Niger Delta(Morley and Guerin, 1996) Baram Delta (Morley et al., 1998; Mor-

ley, 2003). Shale diapirs are also encountered on active continental

margins, where the overpressuring and mobilisation of shales is

attributed to the stacking of thrust slices, e.g. Barbados (Brown

and Westbrook, 1988; Stride et al., 1982; Westbrook and Smith,

1983), the Makran (Stöcklin, 1990; Grando and McClay, 2007), Ara-

kan, Burma (Maurin and Rangin, 2009). Much effort has been ex-

pended in defining criteria by which tectonic, olistostromal and

diapiric mélanges might be distinguished (e.g. Barber et al., 1986;

Camerlenghi and Pini, 2009; Codegone et al., 2012b; Cowan, 1985;

Dilek et al., 2012; Festa et al., 2010; Festa, 2011; Lash, 1987; Or-

ange, 1985; Pini, 1999; Raymond, 1984; Silver and Beutner,

1980; Sengör, 2003; Wakabayashi, 2011).

Experience gained during study of mélanges regions of present

day active tectonics in the Outer Banda Arc and the Outer Sunda

Arc in Indonesia, to which both tectonic and olistostromal origins

have been attributed, but for which substantive evidence of diapir-

ism has been subsequently obtained, suggests that diapiric

mélange is much more common than many structural and tectonic

geologists have appreciated: Diapirism should be considered as an

origin for mélanges, before tectonism or submarine slumping are

automatically assumed.

2. Mélange in the Outer Banda Arc

The island of Timor in eastern Indonesia, just to north of Austra-

lia, forms part of the Outer Banda Arc ( Fig. 1). The island was

formed from Australian Precambrian basement and continental

margin sediments, ranging in age from the Permian to the Pliocene,

imbricated in accretionary complexes and thrust beneath an ophi-

olite nappe, during the collision between the northern continental

margin of Australia and the Banda Volcanic Arc (Barber et al., 1977;

Charlton et al., 1991). The eastern part of Timor (Timor Leste) was

mapped geologically by Audley-Charles (1968), and the strati-

graphic units he established were later adopted by the IndonesianGeological Survey when they mapped the western part of the is-

land (Rosidi et al., 1981) (Fig. 2). During the mapping Audley-

Charles (1965, 1968) recognised an extensive mélange deposit,

the Bobonaro Scaly Clay, containing a variety of blocks in a scaly

clay matrix (Fig. 3) which, following Beneo (1955), he interpreted

as olistostromes, the product of large-scale submarine slumping.

This interpretation was accepted by Hutchison (2007) in his ac-

count of the geology of Timor in the textbook Geological Evolution

of South-east Asia (p. 58).

Audley-Charles (1968) and Carter et al. (1976) regarded the

Bobonaro Scaly Clay as a distinct stratigraphic unit, formed at a

specific period of time, Early Pliocene, N19-20 in Blow’s (1969)

foraminiferal zonal scheme, although Pleistocene forams were

identified in the scaly clay matrix, these were interpreted as being

incorporated by soil creep from overlying raised coral reefs. They

visualised that slumping had occurred by the collapse of submar-

ine fault scarps developed in the accretionary complex, with the

deposition of the blocks into adjacent troughs, where deep-water

clays, which now form the scaly clay matrix, were being deposited.

These escarpments were formed as the result of thrusting during

the subduction/collision between the northern margin of the Aus-

tralian continent and the Banda Arcs.

Later, Hamilton (1979) visited West Timor and described and

illustrated the Bobonaro Scaly Clay Mélange. In the outcrops that

he visited, Hamilton observed that the fabric of the scaly clay ma-

trix had a predominantly northerly dip and suggested that the

mélange had been generated tectonically by southerly-directed

118°E 120° 122° 124° 126° 128° 130° 132° 134°

8°

10°

6°S

12°

14°

118° 120° 122° 124° 126° 128° 130° 132° 134°

Sumba

Savu

Semau

Timor

Tanimbar

Aru

Kai

Banda

V o l c a n i c

A r c

BANDA SEA

Darwin

AUSTRALIA

INDIANOCEANFLOOR

AUSTRALIAN MARGINAL SEDIMENTS

A U S T R

A L I A N

C O N T

I N E N T A

L S H E

L F

1 0 0 0 m 5

0 0 0

m

d e f o r m

a t i o n f r o

n t b a c k t h r u

s t

Accretionary and Collisional Complex

Active mud volcano fields

Volcanic Ar c

6°

8°

10°

12°

14°

1000m

FLORES SEA

Fig. 1. The Banda Arcs Eastern Indonesia, with the island of Timor formed by the collision between the northern margin of Australia and the volcanic arc showing thedistribution of active mud diapirs and mud volcanoes around the Outer Arc (Barber and Brown, 1988).

A.J. Barber / Journal of Asian Earth Sciences 76 (2013) 428–438 429


3/11

overthrusting, during the collision between the northern Austra-

lian margin and the Banda Arc.

Subsequently, in a geophysical cruise in Eastern Indonesia by

the Hawaiian Institute of Geophysics, the Research Vessel KanaKeoki surveyed the Timor accretionary complex and the Australian

Continental Shelf to the south of Timor. The survey mapped the

bathymetry, recorded seismic profiles and used the side-scan sonar

SeaMarc II system (Blackington et al., 1983) to image the Timor

slope, the Timor Trough and the northern part of the Australian

shelf. The seismic section showed that sediments from the Timor

Trough and the Australian margin had been uplifted into the accre-

tionary complex along bedding parallel thrust planes which stee-

pen toward the surface and generate fault-bend folds in the

overlying sediments (Karig et al., 1987) (Fig. 4). Earlier, Upper Pli-

ocene to Recent sediments had been drilled in DSPD 262 on the

floor of the Timor Trough and showed that sediments on the floor

of the trough, to a depth of 400+ m, consist of unlithified radiolar-

ian and clay-rich nanno ooze (Heirtzler et al., 1973). The SeaMARCII side-scan imagery showed fault scarps, both on the Australian

margin and on the Timor slope, together with slumps, débris and

mud flows and sediment-filled slope basins (Fig. 5), as postulated

by Audley-Charles (1965), but the seismic section shows that the

surface of the Australian slope and the accretionary complex is

composed only of recently deposited soft sediments of Pliocene

to Recent age, with no major fault scarps uplifting the underlying

continental shelf sequence from which blocks of lithified sedi-

ments could be derived, to form olistostromes, as postulated by

Audley-Charles (1965, 1968) to account for the Bobonaro Scaly

Clay Mélange on Timor.

A similar survey was conducted by the R.V. Kana Keoki furtherwest, to the south of the island of Sumba, across the accretionary

complex, the trench and the Australian margin (Breen et al.,

1986). SeaMARC II side-scan sonar imagery, together with bathym-

etry and seismic reflection profiling, showed that the surface of the

sea floor on the Australian continental shelf, immediately to the

south of the deformation front of the accretionary complex, is cov-

ered by mounds and ridges (Fig. 6). Neither the side-scan sonar

imagery nor the seismic profiles show any large-scale fault scarps

in the accretionary complex; the upper slopes of the complex are

covered by a thin drape of undisturbed Recent sediments, and

are devoid of structural features (Breen et al., 1986, Fig. 7). Seismic

sections obtained south of the deformation front show that at

intervals of 10 km or so, the regular horizontal reflections in the

bedded sedimentary sequence are disrupted by transparent zones,devoid of reflections, capped by the mounds on the sea floor. These

transparent zones are interpreted as vertical mud diapirs and the

mounds are interpreted as mud volcanoes (Fig. 6).

Breen et al. (1986) correlated the sequence represented in the

profiles with the undisturbed Australian continental marginal se-

quence encountered in boreholes on the Scott Reef ( Rad and Exon,

1982). The deepest reflection (E) is identified as the top of the clas-

tic sequence, which marks the break-up unconformity in the pas-

sive margin of the NW Australian Shelf. A transparent zone

between (E) and (C) is identified as Lower Cretaceous hemipelagic

marine shale deposited on the subsided ocean floor. Overlying

reflectors between (E) and (A) are identified as lithified Upper Cre-

taceous to Miocene pelagic carbonates, with interbedded marls,

deposited on a prograding carbonate shelf, and the zone from (A)to the surface, as Pliocene to Recent pelagic marls. The vertical

124°E 125° 126° 127°

5°

10°

127°126°125°124°E

5°S

10°

0 10 20 30 40 50km

WEST TIMOR

EAST TIMOR

KupangKolbano

Dili

Post-collision Units

Bobonaro Scaly Clay

Pre-Collision Units

Late Miocene-Recent

Permian-Late Miocene

Melange &mud volcanoes

Fig. 2. Geological map of Timor, Eastern Indonesia, showing the extent of the Bobonaro Scaly Clay Mélange: East Timor (Timor Leste) from Audley-Charles (1968); West

Timor from Rosidi et al. (1981).

Fig. 3. Landscape in West Timor with scattered blocks of a variety of lithologies,

some the size of houses, due to the erosion of the clay matrix from an outcrop of

Bobonaro Scaly Clay Mélange.

430 A.J. Barber / Journal of Asian Earth Sciences 76 (2013) 428–438


4/11

transparent zones seen in the seismic sections rise from the level of

the Lower Cretaceous shale at a depth of 1.5 km, and cut across the

bedded reflectors to the base of the surface mounds (Fig. 6). In

passing through the overlying bedded sequence the mobilised clay

is likely to have incorporated blocks of the lithified carbonate units

to form a mélange of Upper Cretaceous to Miocene limestone

blocks in a hemipelagic clay matrix. Scattered occasional reflec-

tions in the transparent zones may from larger blocks. The largest

of the ridges on the sea floor is 200–300 m high, 18 km long with a

width of 2.5 km and extends to a depth of 1.5 km, representing avolume of 70 km3 of mélange.

A subsequent survey by the R.V. Charles Darwin using the GLO-

RIA side-scan sonar system showed that the diapir field extends

over an area of 100 km 50 km on the Australian continental shelf

(Masson et al., 1991). The seismic sections show that continental

margin sediments incorporating the diapirs and the mud volca-

noes, including many hundred cubic kilometres of mélange, are

in the process of incorporation into the toe of the accretionary

complex (Fig. 6).

Westbrook and Smith (1983), in a comparable situation in

Barbados, where mud diapirs and mud volcanoes occur in OrinocoFan sediments on the oceanward side of the deformation front,

passive margin

sediments

syn-rift sediments

br eak -up unc onf or mity

AUSTRALIA TIMORSE NW

2.0

3.0

4.0

5.0

6.0

s e c o n d s t w o - w a y t i m e

2.0

6.0

5.0

4.0

3.0

s e c on d s

t w o-w a y t i m e

0 10 20km

trough fill

slope sediments deformation front

Australian slope Timor TroughTimor slope

Pliocene-Recent

Upper Jurassic - Miocene

Permian -Upper Jurassic

Fig. 4. Interpreted seismic section from the Australian continental shelf across the Timor Trough and the Timor accretionary complex showing that only the most recent

sediments are exposed; the shelf sequence is not exposed and cannot provide blocks to form olistostromes (Karig et al., 1987).

sediment lobes

T I M O R

S L O P E

A U S T

R A L I A

N S L

O P E

1000m

1700

1700

2300

2300

2000

1600

1600

600

1000

1500

1800

1800

2000

2300

2300

2000

124°00’123°45’

123°45’E 124°00’ 124°15’

10°30S

10°45’

11°00’

10°30’

10°45’

11°00’

0 10 20km

floor of Timor Trough

deformation front (inactive)

slump scars

slope basins

normal faults

deformationfront (inactive)

turbiditechannels

anticlines

normal faults

back thrust

Fig. 5. Interpretation of SeaMARC II imagery of the accretionary complex south of Timor shows slumping of soft sediment from the most recent deposits from the Timor

Trough, with no olistostromes containing blocks derived from the underlying continental margin sequence (reinterpreted after Charlton (1987) and personal communication

2012). N.B. The subduction system in the Timor Trough is no longer active. GPS measurements show that Timor Island is accreted to the Australian Plate and is moving NE-

wards at 7.7 cm/yr together with Australia (Genrich et al., 1996).



5/11


6/11

before they were activated by the overpressure generated by the

accretion process.

During mapping in West Timor the Geological Survey of Indone-

sia identified twenty-one mud volcano fields and cross-cutting

mud diapirs, intruded through the other rocks, as the Bobonaro

Scaly Clay Mélange (Rosidi et al., 1981) (Fig. 2). In the Kolbano area,

and in other areas in the southern part of the island, imbricated

and folded Late Cretaceous to Miocene carbonates, form a Late Ter-tiary accretionary complex and are cut by mud diapirs composed of

red scaly clay containing manganese nodules and blocks of Late

Cretaceous to Miocene limestones, forming a mélange (Barber

et al., 1986, Fig. 2). Hydrofracturing of the blocks, with films of

the matrix injected along joints and fractures indicate that the

mud matrix in the diapirs was overpressured (Barber et al., 1986;

Barber and Brown, 1988). Yassir (1987) has demonstrated experi-

mentally that the fabric in scaly clay matrix in mélanges develops

in overpressured clays, without the addition of superimposed

shearing.

The Cretaceous to Miocene limestones and the accompanying

mélange in Kolbano and other areas in the southern part of Timor,

correspond to the Australian marginal sediments and diapirs south

of Sumba, which were incorporated at an earlier stage in the island

arc-continental collision, along a décollement at a level near the

break-up unconformity. There are no active mud volcanoes in this

part of Timor, evidently the diapiric system is now inactive. The

collision commenced in the region of East Timor, and has since ex-

tended to both east and west.

In the island of Semau (Barber et al., 1986) (Fig. 8) and in other

areas in the northern part of Timor (Fig. 2), active mud volcano ex-

trude fluid mud and bubbles of methane and have an oily scum on

the surface of mud pools. Mud in the volcanoes and scaly clay in

the diapirs were derived from Permo-Triassic red shale horizons

and carry blocks of Permo-Triassic sandstone and limestone (Figs. 9

and 10). Evidently, the Permo-Triassic rocks were uplifted into the

accretionary complex from a décollement surface near the base-

ment unconformity with the Australian basement in a process of

underplating (Charlton et al., 1991). Hutchison (2007, p. 320), fol-lowing Audley-Charles (1968), noted that ‘ultramafic’ rocks are

also included in the mélange, showing that some of the diapirs

had intruded the overlying ophiolite nappe. Other diapirs and

mud volcanoes contain blocks of reef material and were intruded

through Pleistocene coral reefs (Barber et al., 1986). The evidence

from the incorporation of the coral blocks and active mud volca-

nism, indicates that compression, overthrusting and the generation

of fluid overpressures continues within the collision complex in the

northern part of Timor to the present day.

Diapirs and active mud volcanoes occur extensively on all the

Banda Outer Arc islands between Timor and Seram (Fig. 1). The

process of the formation of mélanges must be occurring on a very

large scale today as the result of the collision between Australiaand the Banda Arcs.

Fig. 8. The mud volcano field showing small-scale mud volcanoes up to 3 m high,

with fluid mud flows and scattered blocks, in the crater of the 1 km diameter large

mud volcano forming Palau Kambing, SW of Kupang, West Timor. The crater wall in

the background is littered with blocks. The soft clays are eroded during the rainy

season and washed out through a gap in the crater wall (see Barber et al., 1986,Fig. 3).

Fig. 9. Cross-section of a mud diapir containing lensiod and irregular blocks of

limestone and sandstone in a scaly clay matrix in roadside quarry, near Takari, West

Timor. The matrix is intruded along fractures in the blocks, indicating high

overpressures, and the foliar structure of the scaly clay matrix is attributed to flow

rather that to shearing.

Fig. 10. Bedded block of Permian sandstone in varicoloured scaly clay matrix

derived from Permo-Triassic red marls in a mud diapir, exposed by river erosion in

the Noil Toko, near Nenas, West Timor. Patrick Bird provides scale. The location is

shown in Fig. 4 of Barber et al. (1986). (For interpretation of the references to colour

in this figure legend, the reader is referred to the web version of this article.)



7/11

3. Mélange in the Outer Sunda Arc

Outcrops of mélange were mapped in the outer arc islands of

Nias, Simeulue, Siberut, Sipora and Pagai, associated with subduc-

tion of the Indian Ocean floor beneath Sumatra. (Andi Mangga and

Burhan, 1994; Budhitrisna and Andi Mangga, 1990; Endharto and

Sukido, 1994). The mélange contains blocks of serpentinite, gabbro,

basalt, chert, calcilutite, Eocene limestone with foraminifera, gra-nitic and metamorphic rocks together with abundant greywacke

shale and claystone in a scaly clay matrix.

In the 1970s the Scripps Institution of Oceanography (SIO) ob-

tained seismic sections from the Indian Ocean floor, the Sunda

Trench and the Outer Arc Ridge to the SW of Sumatra ( Moore

and Curray, 1980) (Fig. 11A). Karig et al. (1980) made a detailed

study of the trench and the accretionary complex from the SIO

seismic profiles, and then completed a series of traverses across

the Outer Arc Ridge where it is exposed on the island of Nias

(Moore et al., 1980b; Moore and Karig, 1980). On Nias the mélange

deposits, termed the Oyo Complex, occur as a series of NW–SE

trending linear belts parallel to the length of the island, several

hundred metres wide and kilometres in length, alternating with

bedded turbidites of Early Miocene to Early Pliocene age, termed

the Nias Beds (Fig. 12).

In the early 1990s Nias Island was mapped in detail by Samuel

(1994; Samuel et al., 1997) (Fig. 12) with the ages of the rocks very

tightly controlled by detailed microfossil analysis, supported by

petrographic, mineralogical and geochemical analyses. In particu-

lar a systematic study was made of the Oyo Mélange and the rela-

tionships to the bedded units.

From their study of the seismic sections, Moore and Karig

(1976) and Karig et al. (1979) developed a model for the evolution

of the accretionary complex, the development of the forearc ridge

and the geology and structure of Nias. They speculated that the

Oyo Mélange was developed as a trench-fill deposit composed of

fragments of ocean crust and turbidites which slumped down the

face of the accretionary complex as debris flows (olistostromes)

and were subsequently accreted at the toe of the complex (Mooreand Karig, 1980). Further debris flows were derived from fault

scarps developed on the NE side of slope basins formed on top of

the accretionary complex. The resolution of the 1970s seismic

reflection imaging was not sufficiently clear to either confirm or

contradict these interpretations (Fig. 11). Neither debris flows

nor diapirs are seen in the seismic profiles across the Sunda Trench

(Fig. 11A and B). It may require swath mapping or 3D seismic sur-

veys across the trench and the accretionary complex to identify

such flows (e.g. Gee et al., 2007). Karig et al. (1979) further specu-

lated that the chaotic and sheared appearance of the mélange was

due to the dynamic tectonic environment within the developing

accretionary complex, in which original thrust surfaces were con-

tinually reactivated, with the development of new thrust planes,

disrupting the accreted oceanic material and breaking it into

blocks. They were unable to determine the age of the mélange di-

rectly, but inferred that the age was indicated by the youngest

dateable included blocks, the Eocene limestones.

Although no depositional contacts were observed, Moore et al.

(1980a) and Moore and Karig (1980) suggested that the Oyo

Mélange was the oldest unit on Nias, on which the Nias Beds were

deposited unconformably. They suggested that the Nias Beds had

0

1

2

3

4

5

6

NEsecondstwo-way-time

SUNDA TRENCH

Deformation front

Indian Ocean Crust

Accretionary Complex

Outer Arc RidgeMentawai Fault Forearc Basin

0 10 20km

Vertical exaggeration 6.1 X

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

D e p t h i n m

26 28 30

Distance along profile in km32 34 36 38 40

(A) Nias Transect

(B) South Sumatra Transect

42 44 46 48 50 52 54 56 58 60 62 64 66 68

Indian Ocean Crust

Deformation front

Accretionary Complex

Outer Arc Ridge

NE

SW

SW

SUNDA TRENCH

Vertical exaggeration 1.5 X

slope basins

Fig. 11. (A) NE–SW line drawing from seismic profile to the south of Nias, from the Indian Ocean Floor across the Sunda Trench, the accretionary complex and the Outer Arc

Ridge to the Sumatran Forearc Basin (redrawn from Moore et al. (1980b)). (B) NE–SW line drawing from a seismic section offshore South Sumatra. The original section is inKopp and Kukowski (2003).



8/11

been deposited in slope basins on the accretionary complex and

were uplifted and compressed during thrusting, with the growth

of the complex, until they were exposed in Nias.

On the other hand Samuel et al. (1995) found that the bedded

sediments on Nias had been deposited in basins developed on

top of the accretionary complex, bounded to the NE by syn-depo-

sitional extensional faults. They also found that the Upper Palaeo-

gene and Neogene stratigraphic sequences on Nias correspond

with the same sequences in the Banyak and Batu islands, which

lie within the forearc basin to the northeast of Nias, and also in

boreholes in the forearc basin itself. These sequences resemble in

stratigraphy and lithology the units on Nias. Samuel et al. (1995)

therefore concluded from the occurrence of well-rounded quartzpebbles and metamorphic clasts, in the Oligocene and Lower

Miocene sandstones and conglomerates, that the sediments on

Nias were derived from a mature continental provenance, either

basement uplifts in the forearc or the mainland of Sumatra, and

that prior to the Pleistocene, sedimentation extended continuously

from Sumatra across the present forearc basin onto the outer arc

islands, and do not correspond to the deposits in the Sunda Trench.

Samuel (1994) found that in addition to ophiolitic material, ser-

pentinite, gabbro, basalt, calcilutite and chert of ocean floor prove-

nance, at least 50%, and commonly 90% of the blocks in the

mélange had been derived from the bedded Oligocene and Lower

Miocene units, while some outcrops contained clasts of Upper Mio-

cene and even Pleistocene units. He also found that the mud matrix

contained the same microfossils, had the same mineral composi-tion and the same thermal history, yielding the same range of

reefs

reefs

reefs

Gunungsitoli Formation (Plio-Pleistocene)

Ophiolitic basement (B)

C

1°00

1°15'

1°30'N

97°45'97°30'97°15'E

97°15'E 97°30'

1°00'

0°45'

B

B

B

B

B

GUNUNG- SITOLI

TELUKDALAM

Fault

Anticline

Syncline

Lineament

Thrust

Alluvium

Oyo Mélange (blocks in scaly clay)

* Mud volcanoes

))

0 10 20km

Gomo Formation )

Lelematua Formation

Conglomerate Member (Late Oligocene-Early Miocene)

'Nias Beds' (Early Miocene-Early Pliocene)

*

*

1°15'

97°45'

B

C

B

B

B

C

I N D I A N O C E A N

Pagai

S U M A T

R A

6°N 6°

0° 0°

6°6°S

200km100°

100°E

S u n d a T

r e n c h

Simeulue

NIAS

Siberut F i g

. 1 1 A

SUMATRAN FOREARC

F i g . 1 1 B

Fig. 12. Geological and structural map of the Island of Nias, Outer Arc, showing outcrops of the Oyo Mélange and the location of mud volcano fields. Locations marked ‘B’ are

outcrops of coherent ophiolitic basement, in contrast to ophiolitic blocks in the mélange (based on Djamal et al. (1994) and Samuel (1994)). The thrusts shown on the SW side

of the mélange outcrops may not be correct, see text. Inset map shows location of Nias in the Sumatran Forearc and the position of the seismic lines in Fig. 11A and B.



9/11

vitrinite values, as mudstones in the Oligocene to Lower Miocene

succession.Samuel (1994) found that the scaly fabric that pervades the

mélange matrix is commonly vertical, but may be folded and

wrapped around the enclosed clasts, and at the contacts, the fabric

is parallel to the margins of the mélange outcrop (Fig. 13). Karig

et al. (1980) observed that as mélange units are traced along strike

they are in contact with different units of the Nias Beds, and are

sheared and mixed into the mélange. But as we have seen already,

a shearing process is not necessary to impart the scaly fabric to the

clay matrix of the mélanges (Yassir, 1987). Karig et al. (1980) inter-

preted these contacts as high angle reverse faults. However, Sam-

uel et al. (1997) observed that the contacts between the mélange

and the adjacent bedded units are always intrusive, with the ma-

trix penetrating along the bedding planes and fractures in the bed-

ded units. If these observations are correct, the thrusts shownalong the SW margins of the mélange outcrops in geological map

(Fig. 12) are probably erroneous. The mélange was observed to

cut units of all ages from Oligocene to Recent. It appears that the

main period of mélange formation occurred during the Pliocene,

but mélange production continues to the present day, as shown

by the eruption of mud volcano fields (Fig. 12), extruding blocks

in a grey mud slurry, identical in composition and ages to the ma-

trix of the mélange.

Similar mélanges, have been mapped on the other Sumatran

Outer Islands of Simeulue, Siberut, Sipora and Pagai, commonly

with circular outcrops, and associated with active mud volcanoes

(Endharto and Sukido, 1994; Andi Mangga and Burhan, 1994;

Budhitrisna and Andi Mangga, 1990). Evidently as in Timor and

the other island of the Outer Banda Arc System, the outer arc ridge

in the Sunda Arc system continues to be compressed, causing over-

pressure and the mobilisation of clays to form mud diapirs and

mud volcanoes.

4. Conclusions

Contrary to the hypothesis of Audley-Charles (1965), evidence

from Sumba and Timor indicates that there are no débris flows

containing continental shelf blocks, associated with the develop-

ment of the accretionary complex forming at the present day,

which could account for the Bobonaro Scaly Clay Mélange on Ti-

mor. Evidence from Sumba indicates that large volumes of

mélange, in the form of diapirs, were generated by overpressured

fluids in the Australian continental marginal sediments, beforethey were incorporated into the accretionary complex. The

experimental work of Yassir (1987) shows that the presence of a

scaly clay fabric does not necessarily indicate tectonic deformation,

as Hamilton (1979) assumed. However, it is possible for deforma-

tion to be superimposed on mélanges after accretion has ceased,

e.g. Barber et al. (1986) describe mélange sheared along strike-slip

faults in West Timor, and Harris et al. (1998) has suggested that the

mélanges occur along the base of major thrusts developed during

the progress of the collision. It may be that the diapiric mélangeshave provided weak zones along which the thrust planes were

developed. Evidence from Timor and the islands to the east, indi-

cates that compression and thrusting to produce overpressure,

with the formation of mud diapirs and mud volcanoes in the Outer

Banda Arc, due to the collision with Australia, continues to the

present day.

The seismic sections across the Sunda Trench, the accretionary

complex and the Outer Arc Ridge offshore Sumatra show no evi-

dence of mud diapirism from the Nicobar Fan sediments on the In-

dian Ocean floor (Fig. 11A and B), in contrast to the Northwest

Australian Shelf south of Sumba, where the sequence contains a

permeable clastic sequence overlain by impermeable clays which

could be mobilised by overpressures generated by the loading of

the accretionary complex. Although the presence of débris flows

in the Sunda Trench or in slope basins on the developing accretion-

ary complex in the Sunda Arc system, as proposed by Karig et al.

(1979), nor the disruption and break-up of units by thrusts within

the accretionary complex, cannot definitely be ruled out, Samuel’s

(1994; Samuel et al., 1995, 1997) study of the geology of the island

of Nias has shown conclusively that these processes were not

responsible for the formation of the mélanges on Nias. Samuel

(1994) found that the Oyo Mélange Complex was formed as mud

diapirs within extensional sedimentary basins, formed on top of

the accretionary complex. Nor were the mélanges deformed as

the result of the continual reactivation of the accretionary com-

plex, causing the development of thrust planes with further dis-

ruption and the formation of the scaly fabric, as Moore and Karig

(1980) had suggested. As we have seen the occurrence of mud vol-

cano fields on Nias and the other Sunda Outer Arc islands indicatesthat compression-generated overpressures forming diapiric

mélange is still in the process of formation at the present day.

Nevertheless, the olistostromal and tectonic models for the for-

mation of mélanges proposed by Karig et al. (1979) has been so im-

mensely persuasive and influential that it has been invoked as an

explanation for the occurrence of mélanges all over the world;

e.g. Turkey and the Himalayas (Collins and Robertson, 1997; Rob-

ertson and Pickett, 2000; Robertson and Ustaömer, 2011). Hamil-

ton (1979), as a Californian geologist, would have been well

aware of the work at Scripps, which led him to the interpretation

of the Bobonaro Scaly Mélange of West Timor as of tectonic origin,

formed by the process visualised by Karig et al. (1979).

As far as the author is aware no clasts of blueschist or eclogite

have been recorded from the mélanges on Timor or on the OuterSunda Arc islands, which as has been explained originated as dia-

pirs on a continental shelf or in an active continental margin envi-

ronment. Clasts of ophiolitic materials are found in the mélanges

on both Timor and Nias but these have been incorporated when

diapirs have penetrated overlying accreted slices of ocean crust.

Mélanges that contain clasts of blueschists, eclogites and other

high grade metamorphic rocks, often in a serpentinous matrix such

as those in the Franciscan Mélange of California and the Peleru

Mélange Complex of Central Sulawesi have risen diapirically up

the subduction zone from the mantle, as earlier authors have sug-

gested (Cloos, 1984, 1985; Parkinson, 1996).

In a landmark paper, Kopf (2002, Fig. 1) building on an earlier

review by Higgins and Saunders (1967) catalogued the occurrence

of mud volcanism and mud diapirism throughout the world; henoted that they are especially developed on convergent plate

Fig. 13. The margin of a mud diapir exposed in the bank of a tributary stream of the

Oyo River, showing the grey scaly clay matrix, with a fabric parallel to the margin,

cutting and injected along joint fractures in a greywacke sandstone bed, Oyo

Mélange, Nias, Sumatran Outer Arc. Notebook 110 150 mm.



10/11

margins. Mud diapirs and mud volcanoes are particularly abundant

in the collision zone between Africa and Eurasia and in the subduc-

tion and collision zones between the Indian and Australian plates

and Southeast Asia. The floor of the Mediterranean Sea has been

particularly well studied by marine geophysical surveys in the past

two decades (see Camerlenghi and Pini, 2009, Fig. 4). Kopf (2002)

claims that is ‘‘arguably the region with the highest abundance

of MVs (mud volcanoes) and diapirs on Earth’’. Several hundredmud volcanoes and mud diapirs have been discovered on Mediter-

ranean Ridge accretionary complex to the south of Crete, formed

by the subduction of the African Plate beneath the European Plate.

The mud volcanoes have been imaged by seismic surveys and

swath mapping and have been sampled by coring, deep drilling

and the use of submersibles, with study of the blocks and the clay

matrix. It is a remarkable anomaly that although mélanges occur

commonly on the adjacent land areas of Greece, Crete, Cyprus

and Southern Turkey they are invariably attributed to the pro-

cesses of submarine slumping and tectonism, not to mud diapirism

(Camerlenghi and Pini, 2009, Fig. 3). Although mud diapirs may be

difficult to recognise in older mélanges on land because diagnostic

features such as mud volcanoes have long since been eroded away,

and the cross-cutting relationships have been modified or de-

stroyed by later tectonism. However, examples are known where

mélanges are incorporated into metamorphic complexes and have

been deformed and recrystallised to form schists, in which blocks

flattened in the foliation planes are injected by the matrix, showing

evidence of overpressure, as seen in diapiric mélange. Structural

and tectonic geologists working on mélanges on land should con-

sider more seriously the possibility that mud diapirism may have

played a role in their formation. In the recent Special Issue of Tec-

tonophysics (Dilek et al., 2012) there is evidence in the papers by

Festa et al. (2012), Codegone et al. (2012a), Codegone et al.

(2012b) and Wakita (2012) that this possibility is beginning to

be appreciated.

Acknowledgements

The author is indebted to Dr. Tim Charlton for his companion-

ship and support over many years of work on the geology of Timor.

He is also thanked for reinterpreting the side-scan sonar imagery

across the Timor Trough, shown as Fig. 5 in this paper, to clarify

some ambiguities in the original interpretation prepared for his

Ph.D. Thesis in 1987.

References

Aalto, K.R., 1981. Multistage mélange formation in the Franciscan Complex,northernmost California. Geology 9, 602–607.

Andi Mangga, S., Burhan, G., Sukardi, Suryanila, 1994. Geological Map of the Siberut

Sheet, Sumatra, Scale 1:250,000. Geological Research and Development Centre,Bandung.Audley-Charles, M.G., 1965. A Miocene gravity slide deposit from Eastern Timor.

Geological Magazine 102, 267–276.Audley-Charles, M.G., 1968. The Geology of Portuguese Timor. Geological Society,

London, Memoir 4, 76p.Barber, A.J., Brown, K., 1988. Mud diapirism: the origin of mélanges in accretionary

complexes? Geology Today 4, 89–94.Barber, A.J., Audley-Charles, M.G., Carter, D.J., 1977. Thrust tectonics on Timor.

Journal of the Australian Geological Society 24, 51–62.Barber, A.J., Tjokrosapoetro, S., Charlton, T.R., 1986. Mud volcanoes, shale diapirs,

wrench faults and mélange in accretionary complexes, eastern Indonesia.American Association of Petrleum Geologists Bulletin 70, 1729–1741.

Beneo, E., 1955. Les resultants des études pour la récherche petrolifiere en Sicilie(Itale). Proceedings of the 4th World Petroleum Congress, Section 1, 109–124.

Blackington, J.G., Hussong, D.M., Kosalos, J.G., 1983. First Results from aCombination Side-scan and Seafloor Mapping System (SeaMARC II). OffshoreTechnology Conference, Paper 4478.

Blow, W.H., 1969. Late middle eocene to recent planktonic biostratigraphy. In:

Bronniman, P., Lenz, H.H. (Eds.), Proceedings of the 1st International Conferenceon Planktonic Microfossils 1, 1967, Geneva, Switzerland, pp. 199–142.

Breen, N.A., Silver, A.E., Hussong, D.M., 1986. Structural styles of accretionary wedgesouth of Sumba, Indonesia, revealed by SeaMARC II side-scan sonar. Bulletin of the Geological Society of America 98, 1250–1261.

Brown, K.M., Westbrook, G.K., 1988. Mud diapirism and subcretion in the BarbadosRidge Complex. Tectonics 7, 613–640.

Budhitrisna, T., Andi Mangga, S., 1990. The Geology of the Pagai and SiporaQuadrangles, Sumatra, Scale 1:250,000. Geological Research and DevelopmentCentre, Bandung.

Camerlenghi, A., Pini, G.A., 2009. Mud volcanoes, olistostromes and Argille Scagliosein the Mediterranean region. Sedimentology 56, 319–365.

Carter, D.J., Audley-Charles, M.G., Barber, A.J., 1976. Stratigraphic analyses of islandarc continental margin collision in eastern Indonesia. Journal of the GeologicalSociety, London 132, 179–198.

Charlton, T.R., 1987. The Tectonic Evolution of the Kolbano-Timor TroughAccretionary Complex, Southern West Timor. Unpublished Ph. D. Thesis,University of London.

Charlton, T.R., Barber, A.J., Barkham, S.T., 1991. The structural evolution of the TimorCollision Complex, Eastern Indonesia. Journal of Structural Geology 13, 489–500.

Cloos, M., 1984. Flow mélanges and the structural evolution of accretionary wedges.Geological Society of America Special Paper 198, 71–80.

Cloos, M., 1985. Thermal evolution of convergent plate margins: thermal modellingand re-evaluation of isotopic Ar-ages for blueschists in the Franciscan Complexof California. Tectonics 4, 421–433.

Codegone, G., Festa, A., Dilek, Y., 2012a. Formation of Taconic mélanges and brokenformations in the Hamburg Klippe, Central Appalachian Orogenic Belt.Tectonophysics 268–269, 215–229.

Codegone, G., Festa, G., Dilek, Y., Pini, G.A., 2012b. Small-scale polygenetic mélangesin the Ligurian accretionary complex, Northern Apennines, Italy, and the role of shale diapirism in superposed mélange evolution in orogenic belts.Tectonophisics 568–569, 170–184.

Collins, A.S., Robertson, A.H.F., 1997. Lycian mélange, southwest Turkey: anemplaced Late Cretaceous accretionary complex. Geology 25, 255–258.

Cowan, D.S., 1985. Structural styles in Mesozoic and Cenozoic mélanges in theWestern Cordillera of North America. Geological Society of America Bulletin 96,451–452.

Dilek, Y., Festa, A., Ogawa, Y., Pini, G.A. (Eds.), 2012. Chaos & Geodynamics:Mélanges, Mélange forming Processes and their Significance in the GeologicalRecord. Tectonophysics 568–569, 1–388.

Endharto, M., Sukido, 1994. Geological Map of the Sinabang Quadrangle, Sumatra,Scale 1:250,000. Geological Research and Development Centre, Bandung.

Festa, A., 2011. Tectonic, sedimentary and diapiric formation of the Messinianmélange: Tertiary Piedmont Basin (northwestern Italy). In Wakabashi, J., Dilek,Y. (Eds.), Mélanges: Processes of Formation and Societal Significance. GeologicalSociety of America Special Papers, 480. doi: http://dx.doi.org/10.1130/20112480(10).

Festa, A., Pini, G.A., Dilek, Y., Codegone, G., 2010. Mélanges and mélange-forming

processes: a historical overview and new concepts. In: Dilek, Y. (Ed.), AlpineConcept in Geology. International Geology Review, 52, 1040–1105. doi: http://dx.doi.org/10.1080/00206810903557704.

Festa, A., Dilek, Y., Pini, G.A., Codegone, G., Ogata, K., 2012. Mechanisms andprocesses of stratal disruption and mixing in the development of mélanges andbroken formations: redefining and classifying mélanges. Tectonophysics 568–569, 7–24.

Gee, M.R.J., Uy, H.S., Warren, J., Morley, C.K., Lambiase, J.J., 2007. The Brunei slide: agiant submarine landslide on the North West Borneo Margin revealed by 3Dseismic data. Marine Geology 246, 9–23.

Genrich, J.F., Bock, Y., McCaffrey, R., Calais, E., Stevens, C., Subarya, C., 1996.Accretion of the southern Banda Arc to the Australian Plate margin determinedby Global Positioning System measurements. Tectonics 15, 288–295.

Grando, G., McClay, K., 2007. Morphotectonic domains and structural styles in theMakran accretionary prism, offshore Iran. Sedimentary Geology 196, 157–179.

Greenly, E., 1919. The Geology of Anglesey. Memoir of the Geological Survey of Great Britain, vol. 2, 980p.

Hamilton, W., 1979. Tectonics of the Indonesian Region. U.S.G.S. Professional Paper,1078, 345p.

Harris, R.A., Sawyer, R.K., Audley-Charles, M.G., 1998. Collisional mélangedevelopment: geologic associations of active mélange-forming processes withexhumed mélange facies in the western Banda orogen, Indonesia. Tectonics 17,458–480.

Heirtzler, J.R., 13 others, 1973. DSDP Site 262. Initial Reports of Deep Sea DrillingProject, vol. 27, pp. 93–279.

Higgins, G.E., Saunders, J.B., 1967. Mud volcanoes – Their nature and origin.Verhandlungen der Naturforschende Geshellshaft Basel 84, 101–152.

Hsü, K.J., 1968. Principles of mélanges and their bearing on the Franciscan-Knoxvilleparadox. Geological Society of America Bulletin 79, 1063–1074.

Hsü, K.J., 1974. Mélanges and their distinction from olistostromes. In: Dott Jr., R.H.,Shaver, R.H. (Eds.), Modern and Ancient Geosynclinal Sedimentation, vol. 19. Societyof Economic Paleontologists and Mineralogists Special Publication, pp. 721–222.

Hutchison, C.S., 2007. Geological Evolution of South-East Asia, second ed.Geological Society of Malaysia, Kuala Lumpur.

Karig, D.E., Suparka, S., Moore, G.F., Hehunassa, P.E., 1979. Structure and evolutionof the Sunda Arc in the Sumatra region. In: Watkins, J.S., Montadert, L.,Dickerson, P.W. (Eds.), Geological and Geophysical Investigations of the

Continental Margins, vol. 29. American Association of Petroleum GeologistsMemoirs, pp. 223–237.


http://dx.doi.org/10.1130/20112480(10)http://dx.doi.org/10.1130/20112480(10)http://dx.doi.org/10.1080/00206810903557704http://dx.doi.org/10.1080/00206810903557704http://dx.doi.org/10.1080/00206810903557704http://dx.doi.org/10.1080/00206810903557704http://dx.doi.org/10.1130/20112480(10)http://dx.doi.org/10.1130/20112480(10)


11/11

Karig, D.E., Lawrence, M.B., Moore, G.F., Curray, J.R., 1980. Structural framework of thefore-arc basin, NW Sumatra. Journal of the Geological Society, London 137, 77–91.

Karig, D.E., Barber, A.J., Charlton, T.R., Kemperer, S., Hussong, D.M., 1987. Nature anddistribution of deformation across the Banda Arc-Australia collision zone atTimor. Bulletin of the Geological Society of America 98, 18–32.

Kopf, A., 2002. Significance of mud volcanism. Reviews of Geophysics 40, 2.2–2.52.Kopp, H., Kukowski, N., 2003. Backstop geometry and accretionary mechanics of the

Sunda margin. Tectonics. http://dx.doi.org/10.1029/2002TC001420.Lash, G.G., 1987. Diverse mélanges of an ancient subduction complex. Geology 15,

652–655.

Loncke, L., Gaullier, V., Mascle, J., Vendeville, B., Camera, L., 2006. The Nile deep-seafan: an example of interacting sedimentation, salt tectonics and inheritedsubsalt paleotopographic features. Marine Petroleum Geology 23, 297–315.

Masson, D.G., Milsom, J., Barber, A.J., Sikumbang, N., Dwiyanto, B., 1991. Recenttectonics around the island of Timor, Eastern Indonesia. Marine and PetroleumGeology 8, 33–49.

Maurin, T., Rangin, C., 2009. Structure and kinematics of of the Indo-BurmanWedge: recent and fast growth of the outer wedge. Tectonics 28. http://dx.doi.org/10.1029/2008TC992276.

Moore, G.F., Curray, J.R., 1980. Structure of the Sunda Trench lower slope off Sumatra from multichannel seismic reflection data. Marine GeophysicalResearches 4, 319–340.

Moore, G.F., Karig, D.E., 1980. Structural geology of Nias Island, western Indonesia,implications for subduction zone tectonics. American Journal of Science 280,193–223.

Moore, G.F., Billman, H.G., Hehanussa, P.E., Karig, D.E., 1980a. Sedimentology andpaleobathymetry of Neogene trench-slope deposits, Nias Island, Indonesia.

Journal of Geology 88, 161–180.Moore, G.F., Curray, J.R., Moore, D.G., Karig, D.E., 1980b. Variations in geologic

structure along the Sunda forearc, Northeast Indian Ocean. In: Hayes, D.E. (Ed.),The Tectonic and Geologic Evolution of Southeast Seas and Islands, Part 1, vol.23. American Geophysical Union, Geophysical Monographs, pp. 145–160.

Morley, C.K., 2003. Mobile shale related deformation in large deltas developed onpassive and active margins: review and new views. In: Van Rensbergen, P.R.,Hillis, R., Maltman, A., Morley, C.K. (Eds.), Subsurface Sediment Mobilization,vol. 216. Geological Society, London, Special Publication, pp. 381–394.

Morley, C.K., Guerin, G., 1996. Comparison of gravity-driven deformation styles andbehaviour associated with mobile shales and salt. Tectonics 15, 1154–1170.

Morley, C.K., Crevello, P., Ahmad, Zulkifli., 1998. Shale tectonics – deformationassociated with active diapirism: the Jerudong Anticline, Brunei Darussalam.

Journal of the Geological Society, London 155, 475–490.Ogawa, Y., 1998. Tectonostratigraphy of the Glen App area, Southern Uplands,

Scotland: anatomy of an Ordovician accretionary complex. Journal of theGeological Society, London 155, 651–662.

Orange, D.L., 1985. Criteriahelpful in recognizing shear-zone and diapiric mélanges:examples from the Hoh accretionary complex, Olympic Peninsula. GeologicalSociety of America Bulletin 102, 935–951.

Parkinson, C.D., 1996. The origin and significance of metamorphosed tectonic blocksin mélanges: evidence from Sulawesi. Terra Nova 8, 312–323.

Pini, G.A., 1999. Tectonosomes and olistostromes in the Argille Scagliose of theNorthern Apennines, Italy. Geological Society of America Special Papers 335, 73.

von Rad, U., Exon, N.F., 1982. Mesozoic–Cenozoic sedimentary and volcanicevolution of a starved passive margin off northwest Australia. In: Watkins,

J.S., Drake, C.C. (Eds.), Studies in Continental Margin Geology, vol. 34. AmericanAssociation of Petroleum Geologists Memoir, pp. 253–281.

Raymond, L.A., 1984. Mélanges: their nature, origin and significance. GeologicalSociety of America Special Paper 198, 7–20.

Robertson, A.H.F., Pickett, E.A., 2000. Palaeozoic-Early Tertiary Tethyan evolution of mélanges, rift and passive margin units in the Karaburun Peninsula (westernTurkey) and Chios (Greece). In: Bozkurt, E., Winchester, J.A., Piper, J.D.A. (Eds.),Tectonics and Magmatism in Turkey and the Surrounding Area, vol. 173.

Geological Society, London, Special Publications, pp. 43–82.Robertson, A.H.F., Ustaömer, T., 2011. Role of tectonic-sedimentary mélange and

Permian-Triassic cover units, central and southern Turkey, in Tethyancontinental margin evolution. Journal of Asian Earth Sciences 40, 98–120.

Rosidi, H.M.D., Suwitodirdjo, K., Tjokrosapoetro, S., 1981. Geological Map of theKupang-Atambua Quadrangles, 1:250,000. Geological Research andDevelopment Centre, Bandung.

Samuel, M.A., 1994. The Structural and Stratigraphic Evolution of Islands at theActive Margin of the Sumatran Forearc, Indonesia. Unpublished Ph.D. Thesis,University College, London.

Samuel, M.A., Harbury, N.A., Jones, M.E., Matthews, S.J., 1995. Inversion-controlleduplift of an outer-arc ridge: Nias Island, offshore Sumatra. In: Buchanan, J.G.,Buchanan, P.G. (Eds.), Basin Inversion, vol. 88. Geological Society of LondonSpecial Publication, pp. 473–492.

Samuel, M.A., Harbury, N.A., Bakri, A., Banner, F.T., Hartono, L., 1997. A newstratigraphy for the islands of the Sumatran Forearc, Indonesia. Journal of Southeast Asian Earth Sciences 15, 339–380.

Sengör, A.M.C., 2003. The repeated discovery of mélanges and its implications forthe possibility and the role of objective evidence in the scientific enterprise. In:Dilek, Y., Newcomb, S. (Eds.), Ophiolite Concept and the Evolution of GeologicThought, vol. 373. Geological Society of America Special Paper, pp. 385–446.

Silver, E.A., Beutner, E.C., 1980. Mélanges. Geology 8, 32–34.Stöcklin, J., 1990. The Coloured mélange of the Makran: A Product of Diapirism?

Paper Presented at the Symposium on Diapirism, Geological Survey of Iran,Tehran.

Stride, A.H., Belderson, R.H., Kenyon, N.H., 1982. Structural grain, mud volcanoesand other features on the Barbados Ridge Complex revealed by Gloria long-range side-scan sonar. Marine Geology 49, 187–196.

Wakabayashi, J., 2011. Mélanges of the Franciscan Complex, California: Diversestructural settings, evidence for sedimentary mixing, and their connection tosubduction processes. In: Wakabayashi, J., Dilek, Y. (Eds.), Mélanges: Processesof Formation and Societal Significance, vol. 480. Geological Society of AmericaSpecial Paper, pp. 117–141, doi: http://dx.doi.org/10.1130/2011.2480(05).

Wakita, K., 2012. Mappable features of mélanges derived from Ocean PlateStratigraphy in the Jurassic accretionary complexes of Mino and Chichibuterranes in Southwest Japan. Tectonophysics 568–569, 74–85.

Westbrook, G.K., Smith, M.J., 1983. Long décollements and mud volcanoes: evidence

from the Barbados Ridge complex for the role of high fluid pressure in thedevelopment of an accretionary complex. Geology 11, 279–283.

Yassir, N.A., 1987. Mud Volcanoes and the Behaviour of Overpressured Clays andSilts. Ph.D. Thesis, University of London.

http://dx.doi.org/10.1029/2002TC001420http://dx.doi.org/10.1029/2008TC992276http://dx.doi.org/10.1130/2011.2480(05)http://dx.doi.org/10.1130/2011.2480(05)http://dx.doi.org/10.1029/2008TC992276http://dx.doi.org/10.1029/2002TC001420

The Origin of m Langes Cautionary Tales From Indonesia 2013 Journal of Asian Earth Sciences

Documents

Transcript of The Origin of m Langes Cautionary Tales From Indonesia 2013 Journal of Asian Earth Sciences