Deformation microstructures of olivine and pyroxene in...

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Deformation microstructures of olivine and pyroxenein mantle xenoliths in Shanwang, eastern China, nearthe convergent plate margin, and implications forseismic anisotropyYong Parka & Haemyeong Jungaa School of Earth and Environmental Sciences, Tectonophysics Laboratory, Seoul NationalUniversity, Seoul, Republic of KoreaPublished online: 24 Jun 2014.

To cite this article: Yong Park & Haemyeong Jung (2015) Deformation microstructures of olivine and pyroxene in mantlexenoliths in Shanwang, eastern China, near the convergent plate margin, and implications for seismic anisotropy,International Geology Review, 57:5-8, 629-649, DOI: 10.1080/00206814.2014.928240

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Deformation microstructures of olivine and pyroxene in mantle xenoliths in Shanwang, easternChina, near the convergent plate margin, and implications for seismic anisotropy

Yong Park and Haemyeong Jung*

School of Earth and Environmental Sciences, Tectonophysics Laboratory, Seoul National University, Seoul, Republic of Korea

(Received 20 February 2014; accepted 22 May 2014)

Deformation microstructures, including lattice-preferred orientations (LPOs) of olivine, enstatite, and diopside, in mantlexenoliths at Shanwang, eastern China, were studied to understand the deformation mechanism and seismic anisotropy of theupper mantle. The Shanwang is located across the Tan-Lu fault zone, which was formed due to the collision between theSino-Korean and South China cratons. All samples are spinel lherzolites and wehrlites, and LPOs of minerals weredetermined using scanning electron microscope/electron backscattered diffraction. We found two types of olivine LPO:type-B in spinel lherzolites and type-E in wehrlites. Enstatite showed two types of LPO (types BC and AC), and diopsideshowed four different types of LPO. Observations of strong LPOs and numerous dislocations in olivine suggest that samplesshowing both type-B and -E LPOs were deformed in dislocation creep. The seismic anisotropy of the P-wave was in therange of 2.2–11.6% for olivine, 1.2–2.3% for enstatite, and 2.1–6.4% for diopside. The maximum seismic anisotropy of theshear wave was in the range 1.93–7.53% for olivine, 1.53–2.46% for enstatite, and 1.81–6.57% for diopside. Furthermore,the thickness of the anisotropic layer was calculated for four geodynamic models to understand the origin of seismicanisotropy under the study area by using delay time from shear wave splitting, and S-wave velocity and anisotropy frommineral LPOs. We suggest that the seismic anisotropy under the study area can be most likely explained by two deformationmodes that might have occurred at different times: one of deformed lherzolites with a type-B olivine LPO by lateral shearduring/after the period of the Mesozoic continental collision between the Sino-Korean and South China cratons; and theother deformed the wehrlites with a type-E olivine LPO by horizontal extension during the period of change in absoluteplate motion in relation to the westward-subducting Pacific plate.

Keywords: mantle xenoliths; Shanwang; lattice-preferred orientation; olivine; seismic anisotropy

1. Introduction

Since mantle peridotite xenoliths provide informationabout the deformation and metamorphic processes of theupper mantle lithosphere (Mercier and Nicolas 1975),these rocks have been perceived as being crucial in inter-preting both the geophysical and geochemical environ-ments and the deformation mechanisms in the uppermantle. In particular, the seismic anisotropic layer is con-sidered to be related to the presence of mainly olivine andorthopyroxene in the mantle, and therefore an understand-ing of the lattice-preferred orientations (LPOs) of theseminerals in nature is important in distinguishing the defor-mation processes of the upper mantle (Nicolas andChristensen 1987; Vinnik et al. 1989; Silver 1996;Savage 1999; Jung and Karato 2001a; Park and Levin2002; Nakajima and Hasegawa 2004; Kneller et al.2005; Mainprice 2007; Karato et al. 2008; Long andSilver 2008, 2009a, 2009b; Skemer et al. 2012; Long2013). From the seismic anisotropy calculated using theLPOs of olivine and pyroxenes in mantle xenoliths, Peraet al. (2003) presented the first petrophysical results ofupper mantle structure constraints beneath the Torre Alfinaarea in central Italy, by considering four geodynamic

models: upwelling, lateral shear, horizontal extension,and tilted slab. Subsequently, similar studies were con-ducted to constrain the structures beneath the Sanbagawabelt in southwest Japan (Tasaka et al. 2008), the RioGrande rift in New Mexico, USA (Satsukawa et al.2011), and northeast Tasmania, Australia (Michibayashiet al. 2012).

The LPO and seismic anisotropy of olivine are wellknown in both ‘dry’ and ‘wet’ conditions in experimentalstudies (Carter and Ave’Lallemant 1970; Zhang andKarato 1995; Bystricky et al. 2000; Zhang et al. 2000;Jung and Karato 2001a; Katayama et al. 2004; Jung et al.2006, 2009b; Katayama and Karato 2006; Karato et al.2008; Ohuchi et al. 2011, 2012) and within many naturalrocks (Nicolas and Christensen 1987; Ben Ismaı̈l andMainprice 1998; Mizukami et al. 2004; Sawaguchi 2004;Katayama et al. 2005; Vauchez et al. 2005; Michibayashiet al. 2006, 2009; Skemer et al. 2006, 2010; Tommasiet al. 2008; Jung 2009; Jung et al. 2009a, 2013, 2014;Kamei et al. 2010). According to previous experimentalstudies, the type-E fabric (defined as the crystallographic[100] axis of olivine aligned subparallel to the shear direc-tion and the [001] axis aligned subnormal to the shear

*Corresponding author. Email: [email protected]

International Geology Review, 2015Vol. 57, Nos. 5–8, 629–649, http://dx.doi.org/10.1080/00206814.2014.928240

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plane) is found under low stress and moderate water con-tent. In contrast, the type-B fabric (defined as the crystal-lographic [001] axis of olivine aligned subparallel to theshear direction and the [010] axis aligned subnormal to theshear plane) is found under high stress and/or a moderate–high water content. It is considered that finding the type-Bolivine LPO in nature is important because trench-parallelseismic anisotropy of fast shear waves found in manysubduction zones can be attributed to type-B LPO (Jungand Karato 2001a; Nakajima and Hasegawa 2004; Knelleret al. 2005; Long and van der Hilst 2005, 2006; Nakajimaet al. 2006; Karato et al. 2008). However, previous studiesrelated to the LPO and seismic anisotropy of orthopyrox-ene are limited (Christensen and Lundquist 1982; Vauchezet al. 2005; Skemer et al. 2006; Hidas et al. 2007;Soustelle et al. 2010), and Jung et al. (2010) recentlyclassified the LPOs of enstatite into one typical type-ACand three newly defined types: AB, BC, and ABC (in thisnomenclature, the first and second capital letters representthe slip plane and slip direction, respectively).

The Sino-Korean craton (or North China craton) is oneof the major eastern Eurasian Archaean cratons on Earth,and it is considered that refractory ancient mantle roots aredepleted beneath this craton, with significant buoyancyand high viscosity (Griffin et al. 1998b; Kelemen et al.1998). Many analytical geochemical studies have revealedthat the refractory lithosphere can be changed to morefertile materials by the interaction between the astheno-sphere and lithosphere, or cratonic upper mantle (Griffinet al. 1998a; Kelemen et al. 1998; O’Reilly et al. 2001).According to several studies, such mantle metasomatism isconsidered to occur beneath the Sino-Korean craton(Zhang and Sun 2002; Zhang 2005; Zheng et al. 2005a,2005b, 2006; Zhang et al. 2007; Chu et al. 2009; Xiaoet al. 2010; Xiao and Zhang 2011), and previous studieshave calculated the seismic anisotropy of shear wavestherein using SKS splitting measurements (Iidaka andNiu 2001; Zhao and Zheng 2005; Zhao et al. 2007b,2008, 2009, 2011, 2013; Huang et al. 2008; Liu et al.2008; Chang et al. 2009; Zhao and Xue 2010). Thesestudies reveal an E–W- to WNW–ESE-trending polariza-tion direction of fast shear waves in eastern China (nearthe Shanwang area), with a direction subparallel to theaverage absolute plate motion direction of the Sino-Korean craton (Gripp and Gordon 2002). However, theorigin of such seismic anisotropy is not yet wellunderstood.

In this study, deformation microstructures (includingthe LPOs of olivine, orthopyroxene (enstatite), and clin-opyroxene (diopside)) in mantle xenoliths from Shanwangin eastern China were studied to understand the deforma-tion mechanism and seismic anisotropy in the upper man-tle. The seismic anisotropy of each mineral was calculated,and the thickness of the anisotropic layer under the studyarea was estimated for four geodynamic models (Pera

et al. 2003) using both the delay time from shear wavesplitting in eastern China and S-wave velocity and aniso-tropy from the LPOs of minerals in the mantle xenoliths.In this study, we suggest using the deformation mode ofthe upper mantle under the study area using the petrofab-rics of olivine found in this study to explain seismicanisotropy in eastern China (near Shanwang).

2. Geological background

The Sino-Korean craton is divided into three regions, theWestern and Eastern blocks and the Trans-North ChinaOrogen (Central Zone in Figure 1). The eastern boundaryof the Trans-North China Orogen nearly coincides withthe North–South Gravity Lineament (NSGL), which is amajor geophysical feature in the central Sino-Korean cra-ton that separates the Archaean Liaolu and the ArchaeanOrdos cratonic nuclei (Zhao et al. 2000, 2001; Zheng et al.2001, 2005a). To the west of the NSGL, in an area thatincludes the Western Block and the Central Zone, theArchean Ordos nucleus is found as a thick lithosphere

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Figure 1. Simplified geological map showing the major tectonicsetting and study area of Shanwang in eastern China. EB (redarea) and WB (blue area) represent the Eastern and Westernblocks of the Sino-Korean craton, respectively. CZ (green area)is the Central Zone and indicates the Trans-North China Orogen(modified after Zheng et al. 2005a, 2005b).

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(~200 km), with a relatively low heat flow (40–60 mW/m2) and strong negative Bouguer gravity anomalies. Incontrast, to the east of the NSGL, within the EasternBlock, the Archaean Liaolu nucleus is characterized by athin lithosphere (~80–110 km), high heat flow (60–80 mW/m2), and weak negative to positive regionalBouguer anomalies (Yuan 1996; Griffin et al. 1998a; Huet al. 2000; Chen et al. 2006, 2008; Sodoudi et al. 2006;Lysak 2009; Zhao et al. 2009). In particular, geochemicalstudies have been conducted on mantle xenoliths from thePalaeozoic diamond-bearing kimberlites in Mengyin andFuxian counties (Griffin et al. 1998a; Zheng and Lu 1999;Zhang et al. 2008), and from Cenozoic basalts found inthe Shanwang, Hebi, and Qixia areas (Zheng et al. 1998,2001, 2005a, 2006; Fan et al. 2000; Gao et al. 2002;Zhang 2005; Ying et al. 2006; Zhang et al. 2007, 2010,2011; Xiao et al. 2010; Xiao and Zhang 2011). Suchstudies have indicated that the newly accreted fertile litho-spheric mantle underplated in the late Mesozoic–Cenozoiclithosphere beneath the Eastern Block, and it has thereforebeen proposed that a thick cratonic lithosphere (~200 km)with a cold geotherm (~40 mW/m2) was replaced by a thinlithosphere (~80–110 km) with a hot geotherm in theCenozoic by asthenospheric upwelling.

The study area (in Shanwang, Eastern China) islocated within the Tan-Lu fault zone in the ArchaeanLiaolu nucleus. Three episodes of volcanism haveoccurred, the first eruption occurring in 18.2–16.8 Ma(K-Ar method; Jin 1985). Sr-Nd isotopic analyses ofNeogene basalts in the study area by Zhi et al. (1994)show values of 143Nd/144Nd = 0.512744–0.512967 and87Sr/86Sr = 0.70349–0.70450. And Fan et al. (2000) cal-culated values from spinel peridotite xenoliths in easternChina from a depleted mantle composition (143Nd/144Nd = 0.5135, 87Sr/86Sr = 0.7035) to an enriched mantlecomposition (143Nd/144Nd < 0.51265 and 87Sr/86Sr > 0.7045). These results indicate that a depletedmantle source related to asthenospheric upwelling existsbeneath this area. Recently, Xiao and Zhang (2011)observed high 187Os/188Os ratios in peridotite xenolithswithin the Tan-Lu fault zone, and discovered that the187Re/188Os values of wehrlite xenoliths were higherthan those of the lherzolite xenoliths in Shanwang andother Cenozoic basalts. As a result, they interpreted thatthe lherzolite was replaced as wehrlite by a progressivemetasomatic change between a lherzolite mantle and aninfiltrating metasomatic melt, and that the Tan-Lu faultzone might play an important role as a major melt-infil-trating channel for asthenospheric upwelling in the litho-spheric mantle beneath the eastern Sino-Korean craton(Xiao et al. 2010; Xiao and Zhang 2011).

Equilibrium P-T conditions in the Shanwang area werereported by Zheng et al. (2006), who also found garnet-bearing peridotite xenoliths from the lavas of episode 1volcanism (16.8–18.2 Ma; Jin 1985). Therefore, they

estimated a pressure of 16–24 kbar and a temperature of1000–1180°C in this area, using a combination of a Grt-Opx barometer (Brey and Khler 1990), based on Al parti-tioning, and both the Grt-Cpx (Ravna 2000) and the Grt-Opx (O’Neill and Wood 1979) Fe–Mg exchange thermo-meters. They considered that these estimated P-T valuescorresponded well to the surface heat flow (80 mW/m2) ofthe conductive model geotherm in eastern China, andoverlapped the range of values derived for garnet perido-tite xenoliths from different Cenozoic basalts in theNushan area (Xu et al. 1998, 2000).

3. Methods

3.1. Sample description

Six mantle xenoliths were collected from the lavas ofepisode 1 volcanism erupted at ~16 Ma in the Shanwangarea, eastern China. Petrologically, all samples are spinellherzolites (samples 565–1, 565–2, and 568) or wehrlites(samples 561, 569, and 570), based on the IUGS scheme(Le Maitre 2002), and the size of these xenoliths is in therange of 5–13 cm. In the case of lherzolite, samples con-sist mainly of olivine (58–70%), clinopyroxene (Cpx, 13–18%), and orthopyroxene (Opx, 16–27%), whereas thewehrlite samples consist mainly of olivine (63–83%) andCpx (17–37%) and both include minor minerals such asmagnetite and spinel. The optical photomicrographs ofrepresentative samples for wehrlite (561) and lherzolite(565–1) were taken under crossed polarized light(Figure 2), and both samples showed a porphyroclastictexture, elongated grains of olivine and pyroxene, andundulose extinction of olivine. Figure 2(d) shows well-developed subgrain boundaries in olivine. Although thelack of garnet in our xenoliths indicates that samples camefrom below 60 km depth, Zheng et al. (2006) reportedgarnet-bearing lherzolites and garnet coexisting with spi-nel in the peridotite xenoliths, suggesting that sampleswere derived from the garnet–spinel transition zone(~60–80 km) beneath the Shanwang area. This range ofdepth is within the lithosphere in the eastern Sino-Koreancraton. There are many geochemical studies indicating thatthe Shanwang xenoliths were derived from the newlyaccreted lithospheric mantle underplated in the lateMesozoic–Cenozoic lithosphere (Zheng et al. 1998,2005a, 2005b, 2006; Zhang et al. 2007; Xiao et al.2010; Xiao and Zhang 2011).

3.2. Determination of LPOs and calculation of seismicanisotropies

Electron backscattered diffraction (EBSD) patterns wereused to determine the LPOs of olivine, Opx, and Cpxfrom a thin section of sample (Prior et al. 1999; Junget al. 2006, 2010). HKL’s EBSD system with a

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NordlysII detector attached to the scanning electronmicroscope (SEM, JEOL JSM 6380) was used in thisstudy, and the analysis was performed at the School ofEarth and Environmental Sciences (SEES), SeoulNational University (SNU), Korea. Foliation of the sam-ples was determined by both compositional layering ofpyroxene and the shape-preferred orientation ofdeformed grains, such as elongated grains of pyroxene(Passchier and Trouw 1996). Lineation of the sampleswas determined by grain shape analysis of digitizedlines from the elongated olivine and pyroxene grainboundaries in the foliation plane, using the method ofPanozzo (1983, 1984). The method used to determinelineation by grain shape analysis is shown in moredetail in supplementary Figure S1 (see http://dx.doi.org/10.1080/00206814.2014.928240). The LPO of themineral was measured in the XZ plane of thin sections,where the X- and Z-directions coincide with the linea-tion and the direction normal to foliation, respectively.Sections of samples were polished using 600-, 3000-,and 6000-mesh polishing powders, and 1 μm diamondpaste. The sections were then polished using Syton(0.06 μm colloidal silica slurry) to remove mechanicalsurface damage using a chemical/mechanical polishingtechnique (Lloyd 1987). To prevent charging in theSEM, thin sections were coated with ~3 nm carbonafter polishing. The section surface was tilted at 70° tothe incident electronic beam in the chamber, and theconditions of EBSD analysis were as follows: accelerat-ing voltage 20 kV, working distance 15 mm, and spot

size 60. All EBSD patterns were manually indexed foraccuracy using HKL’s Channel 5 software at theTectonophysics Laboratory, SEES, at SNU. AfterEBSD analysis, the uncorrelated grain pairs were deter-mined from the data and the fabric strength of thesample was estimated by calculating the misorientationindex (M-index) (Skemer et al. 2005). The seismicvelocity and anisotropy of each mineral were calculatedusing both the LPO data from the EBSD analysis andthe software program (Mainprice 1990) for the elasticconstants for olivine (Abramson et al. 1997), enstatite(Chai et al. 1997), and diopside (Collins and Brown1998).

3.3. Estimation of stress

To estimate stress magnitude, the free dislocation densityof olivine in samples was observed using a SEM technique(Karato 1987; Karato and Lee 1999; Jung and Karato2001a; Karato and Jung 2003). The samples were deco-rated with oxygen for 1 hour at 800°C (Kohlstedt et al.1976b) to observe the dislocation microstructure using anSEM, and polished using Syton to remove the thin oxidelayer on the surface. The decorated samples were coatedwith carbon after polishing, and the dislocations in olivinewere imaged as a backscattered electron (BSE) imageusing the SEM (JEOL JSM 6380) in SEES, SNU, withthe following conditions: 15 kV accelerating voltage,10 mm working distance, 20 nA beam current, and 60spot size. The relationship between dislocation density and

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Figure 2. Optical photomicrograph of representative samples of lherzolite and wehrlite. (a) and (b) Optical photomicrograph of XZplane using cross-polarized light showing a porphyroclastic texture for (a) wehrlite (sample 561) and (b) lherzolite (sample 565-1).Elongated olivine and enstatite are visible. Ol, olivine; Di, diopside; En, enstatite; and Spl, spinel. (c) Optical photomicrograph showingundulose extinctions (white arrows) of olivine (sample 561). (d) Backscattered electron (BSE) image showing dislocation microstructureswithin olivine. The white arrows indicate subgrain boundaries (sample 561).


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stress is now shown (Kohlstedt and Goetze 1974;Kohlstedt et al. 1976a):

σ1 � σ3 ¼ αμbρ 1=2ð Þ; (1)

where α is a numerical parameter, μ is the shear modulus,b is the length of the Burgers vector of dislocation, σ is thestress, and ρ is the free dislocation density. In this study,the values of α, μ, and b were referred from those pre-sented in several papers, to ensure the validity of estimatedresults (Goetze and Kohlstedt 1973; Kohlstedt and Goetze1974; Kohlstedt et al. 1976a; Bai and Kohlstedt 1992;Jung and Karato 2001a; Karato and Jung 2003).Dislocation densities were measured from 30 grains ofeach sample using a ‘first principle’ method (Karato andLee 1999):

ρ ¼X

l.V ; (2)

where ∑ l is the total length of dislocations in a volume V,which were then averaged to obtain the stress of thesamples.

Stress magnitudes in the samples were also estimatedfrom the relationship between stress and recrystallizedolivine grain size. To use the recrystallized grain sizepiezometer (Karato et al. 1980; Van der Wal et al. 1993;Jung and Karato 2001b), the average recrystallized grainsizes in olivine were measured using the linear interceptmethod in two dimensions, and were then multiplied bythe same correction factor of 1.5 for three-dimensionalgrain sizes (Gifkins 1970; Russ and Dehoff 2000).

3.4. Measurement of water content

The water content (or hydroxyl concentration) of olivine,Opx, and Cpx for each sample was measured usingFourier transformation infrared (FTIR) spectroscopy. Inthis study we used a Nicolet 6700 FTIR spectrometerwith a Continuum IR microscope at the TectonophysicsLaboratory, SEES, SNU. All samples were polished onboth sides down to a thickness of 83–275 μm, and weredried in an oven at 120°C for more than 24 h beforemeasurement of water content. The water content withina single crystal was measured by focusing the IR beam(aperture size 50 × 50 μm) on clean areas without crackingand grain boundaries using unpolarized transmitted light,and the KBr beam-splitter and an MCT detector withOMNIC software were used. N2 gas was flushed to elim-inate moisture from the atmosphere by purging the samplechamber during FTIR measurements. A series of 128scans were accumulated for each FTIR spectrum, with aresolution of 4 cm−1. The water content was calculatedusing Paterson’s calibration (1982) for the range of wavenumbers 3100–4000 cm−1, because the range is dominated

by the O-H bonds stretching vibrations (Paterson 1982).The water content was determined by averaging the valuesof 10–15 grains for each sample.

4. Results

4.1. LPOs of olivine, enstatite, and diopside

The LPOs of olivine, enstatite, and diopside are shown inthe pole figure (Figure 3). The LPOs of olivine for lher-zolite (samples 565-1, 565-2, and 568) are similar to type-B (the crystallographic [001] axes of olivine were alignedsubparallel to the lineation of the rock, and the [010] axeswere strongly aligned subnormal to the foliation of therock), whereas the LPOs of olivine for wehrlite (samples561, 569, and 570) are similar to type-E (the crystallo-graphic [100] of axes of olivine were aligned subparallelto the lineation of the rock, and the [001] axes werealigned subnormal to the foliation of the rock)(Figure 3). Types of olivine LPO are summarized inTable 1. According to previous studies (Jung and Karato2001a; Katayama et al. 2004; Jung et al. 2006), the olivinetype-B fabrics were found under high stress and/or mod-erate–high water content while the olivine type-E fabricswere found at low stress and moderate water content.

Two types of LPO for enstatite were found (Figure 3):AC and BC (where the initial letter represents the slipplane and the second indicates the slip direction in thisnomenclature, and the letters A, B, and C correspond tothe direction of [100], [010], and [001], respectively). TheLPO of enstatite for sample 568 is type-AC (the crystal-lographic [001] axes of enstatite were aligned subparallelto the lineation of the rock, and the [100] axes werealigned subnormal to the foliation), as has frequentlybeen reported (Christensen and Lundquist 1982; Junget al. 2010). However, the LPO of enstatite for samples565-1 and 565-2 was found to be type-BC (where thecrystallographic [001] axes of enstatite were aligned sub-parallel to the lineation, and the [010] axes were alignedsubnormal to the foliation) (Figure 3), which has rarelybeen reported (Jung et al. 2010).

Historically, the LPOs of diopside have not yet beendefined as a specific type; however, the LPO types ofanother clinopyroxene, omphacite, have previously beenclassified as type-S, -L, and -SL (Helmstaedt et al. 1972;Godard and van Roermund 1995; Mauler et al. 2001;Brenker et al. 2002; Zhang et al. 2006). The diopside inour study showed four different types of LPO (Figure 3).Sample (561) showed that the crystallographic [001] axesof diopside were strongly aligned subparallel to lineationof the rock, and the [100] axes weakly aligned subnormalto the foliation. However, two samples (568 and 569)showed that the crystallographic [100] axes were alignedsubparallel to lineation, and the [001] axes stronglyaligned subnormal to the foliation. The other sample


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side

(Cpx

)forlherzolite(565

-1,5

65-2,and

568)

andwehrlite

samples

(561

,569

,and

570).P

olefigu

resarepresentedin

the

lower

hemisph

ereusingan

equal-area

projectio

n.Ahalf-scatterwidth

of20

°was

used.T

hecolour

coding

refersto

thedensity

ofdatapo

ints(con

toursin

thepo

lefigu

rescorrespo

ndto

themultip

lesof

uniform

distribu

tion).S,foliatio

n;L,lin

eatio

n;andN,nu

mberof

grains.


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(565-1) showed that the [010] axes were aligned subpar-allel to lineation and the [001] axes were aligned subnor-mal to the foliation. The sample 565-2 showed that the[001] axes were aligned subparallel to the lineation and the[010] axes were aligned subnormal to the foliation, similarto the type-L of omphacite. Although sample 570 unex-pectedly revealed the strongest LPO of all the samples,this was attributed to the large porphyroclasts of diopside(diameter 3–5 mm).

4.2. Seismic anisotropy

The seismic anisotropies of P and S-waves (AVp and AVs)for olivine, enstatite, and diopside are shown in Figure 4and Table 2. The seismic anisotropy of the P-wave (Vp)was in the range 2.2–11.6% for olivine, 1.2–2.3% forenstatite, and 2.1–6.4% for diopside. The maximum ani-sotropy of the shear wave (AVs) was in the range 1.93–7.53% for olivine, 1.53–2.46% for enstatite, and 1.81–6.57% for diopside. In the samples of olivine showing atype-B LPO (lherzolites for 565–1, 565–2, and 568), thepolarization direction of the fast S-wave (Vs1) was sub-normal to the lineation for the vertically propagating S-waves (Figure 4(a)). In contrast, the polarization directionof Vs1 for olivine with a type-E LPO (wehrlites for 561,569, and 570) was subparallel to lineation (Figure 4(b)).For enstatite, all of the Vs1 polarization directions weresubparallel to lineation (Figure 4(a)). The diopside in thewehrlites ensured that the polarization direction of Vs1was subparallel to lineation for the vertically propagatingS-wave (Figure 4(b)), whereas that of diopside in thelherzolites was subnormal to lineation, and was the samein the case of olivine (Figure 4(a)). After combining theseismic anisotropy of all minerals for each sample basedon the analysed modal composition in Table 1, all of thecontours and polarization directions of the fast S-wave(Vs1) were found to be similar to those of olivine(Figure 4(c)). However, the P- and S-wave anisotropieswere reduced to 1.9–8.4% and 2.48–5.70%, respectively(Figure 4(c) and Table 2). As a result, the seismic

anisotropies of the whole rocks for each sample werelower than that of olivine because of the additional orien-tation data of enstatite and diopside, except for those insample 570, where the seismic anisotropy of diopside wasunexpectedly stronger than that of olivine.

4.3. Stress estimation of sample

The stress of samples was estimated using the relationshipbetween free dislocation density and stress, and using therecrystallized grain-size piezometer (as demonstrated inSection 3.4). Dislocation microstructures in olivine areshown in Figure 5. In the samples showing olivine type-ELPO,well-developed subgrain boundaries were observed in alarge fraction of the grains. In contrast, few subgrain bound-aries and mostly straight dislocations were observed in sam-ples with type-B olivine LPO. Using Equation (1) anddifferent constants from several papers, we estimated thestress of samples and then compared these results (Table 3).The free dislocation density (ρ) of the samples was calculatedto be between 0.270 × 1012 and 0.384 × 1012 m−2. This resultled us to calculate the stress of samples as being in the range62–74 ± 20 MPa by following the values of Goetze andKohlstedt (1973), 51–60 ± 20 MPa by Kohlstedt and Goetze(1974), 39–51 ± 20 MPa by Bai and Kohlstedt (1992), and50–64 ± 20MPa by Jung and Karato (2001a). In addition, thestresses obtained from the recrystallized grain-size piezometer(Jung andKarato 2001b) were estimated to be σ = 18 ± 6MPaand σ = 44 ± 13MPa for samples with an olivine type-E LPO(561) and type-B (565-1), respectively. These results showthat the sample with an olivine type-B LPO deformed atrelatively higher stress than that with type-E.

4.4. Water content

Water content was determined for minerals in samples. FTIRspectroscopy showed that most samples were dry in olivine(50–120 ± 30 ppm H/Si), except for one sample (561) con-taining a moderate amount of water (200 ± 30 ppm H/Si).However, the coexisting enstatites and diopside contained

Table 1. Results of modal composition, LPOs, and fabric strength (M-index).

Sample

Analysed modal composition Type of LPOs1 M-index2

Ol (%) Opx (%) Cpx (%) Ol Opx Ol Opx Cpx

561 62.9 – 37.1 E – 0.157 – 0.057565-1 58.4 27.0 14.6 B BC 0.156 0.053 0.103565-2 69.7 17.8 12.5 B ~BC 0.165 0.055 0.109568 66.7 15.8 17.5 ~B AC 0.117 0.057 0.056569 79.2 – 20.8 ~E – 0.134 – 0.083570 82.9 – 17.1 ~E – 0.037 – 0.229

Notes: 1LPO types of olivine and enstatite (Opx) were classified by Jung et al. (2006) and Jung et al. (2010), respectively.2The M-index was calculated using the uncorrelated grain pairs determined from LPO data (Figures 3(a–c)) showing the fabric strength of minerals(Skemer et al. 2005).


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Vp

Co

nto

urs

(km

/s)

Vp

Co

nto

urs

(km

/s)

Vp

Co

nto

urs

(km

/s)

AV

s C

on

tou

rs (

%)

AV

s C

on

tou

rs (

%)

AV

s C

on

tou

rs (

%)

Vs1

Po

lari

zati

on

(%

)

Vs1

Po

lari

zati

on

(%

)V

s1 P

ola

riza

tio

n (

%)

Oliv

ine

Oliv

ine

Dio

psi

de

6.79

6.79

7.42

7.42

6.30

6.30

0.21

0.21

0.35

0.35

0.19

0.19

8.83

8.85

8.60

7.95

7.92

7.97

Ani

sotr

opy

= 10

.5%

Ani

sotr

opy

= 11

.1%

Ani

sotr

opy

= 7.

6%

565-

1N

= 3

37

565-

2N

= 5

64

568

N =

784

7.53

7.53

6.70

1.93

1.93

0.21

0.21

0.25

0.02

0.02

8.95

8.78

8.42

7.97

7.99

8.24

Ani

sotr

opy

= 11

.6%

Ani

sotr

opy

= 9.

5%

Ani

sotr

opy

= 2.

2%

561

N =

319

569

N =

548

570

N =

723

6.70

0.25

Vp

Co

nto

urs

(km

/s)

AV

s C

on

tou

rs (

%)

Vs1

Po

lari

zati

on

(%

)

En

stat

ite

2.02

2.02

1.53

1.

53

2.46

2.46

0.02

0.02

0.02

0.02

0.02

0.02

8.24

8.20

8.22

8.07

8.10

8.03

Ani

sotr

opy

= 2.

0%

Ani

sotr

opy

= 1.

2%

Ani

sotr

opy

= 2.

3%

565-

1N

= 1

56

565-

2N

= 1

44

568

N =

185

Vp

Co

nto

urs

(km

/s)

AV

s C

on

tou

rs (

%)

Vs1

Po

lari

zati

on

(%

)

Dio

psi

de

1.81

1.81

3.03

3.03

6.57

6.57

0.02

0.02

0.04

0.04

0.30

0.30

8.37

8.26

8.04

7.93

7.79

Ani

sotr

opy

=

Ani

sotr

opy

=

Ani

sotr

opy

= 5.

8%

2.1%

5.3%

561

N =

188

569

N =

144

570

N =

149

8.21

4.34

4.34

3.18

3.18

2.93

2.93

0.00

0.00

0.19

0.19

0.04

0.04

8.38

8.39

8.28

7.86

7.95

7.92

Ani

sotr

opy

= 6.

4%

Ani

sotr

opy

= 5.

3%

Ani

sotr

opy

= 4.

4%

565-

1N

= 8

4

565-

2N

= 1

01

568

N =

206

X

Y Z

X:

linea

tio

nZ

:

to

fo

liati

on

(a)

Lh

erzo

lite

(b)

Weh

rlit

e

Figure4.

Seism

icanisotropy

calculated

from

LPOsandelastic

constantsof

each

mineral.The

E–W

directioncorrespo

ndsto

thelin

eatio

n(X

)of

samples.The

midpo

intof

the

stereographicprojectio

nisthedirectionno

rmalto

thefoliatio

n(Z).Azimuthalanisotropy

ofP-w

ave(V

p),p

olarizationanisotropy

ofS-w

aves

(AVs),and

polarizatio

ndirectionof

fast

shearwave(V

s1)areshow

nfor(a)lherzolite,

(b)wehrlite,and(c)who

lerock.The

blacksquare

andop

encircle

representmaxim

umandminim

umvelocity

oftheP-w

avein

Vp

contou

rs,andmaxim

umandminim

umanisotropy

ofS-w

aves

inAVscontou

rs,respectiv

ely.


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(c)

Wh

ole

ro

ck

Vp

Co

nto

urs

(km

/s)

AV

s C

on

tou

rs (

%)

Vs1

Po

lari

zati

on

(%

)V

p C

on

tou

rs (

km/s

)A

Vs

Co

nto

urs

(%

)V

s1 P

ola

riza

tio

n (

%)

4.20

4.20

5.34

5.34

4.54

4.54

0.17

0.17

0.29

0.29

0.13

0.13

8.56

8.66

8.47

7.97

7.97

8.00

Ani

sotr

opy

=7.1

%

Ani

sotr

opy

= 8.

2%

Ani

sotr

opy

= 5.

7%

568

N =

117

5O

l: 78

4(67

%)

En:

185

(16%

)D

i: 20

6(17

%)

565-

2N

= 8

09O

l: 56

4(70

%)

En:

144

(18%

)D

i: 10

1(12

%)

565-

1N

= 5

77O

l: 33

7(58

%)

En:

156

(27%

)D

i: 84

(15%

)

Lh

erzo

lite

5.18

5.18

5.70

5.70

2.48

2.48

0.12

0.12

0.29

0.29

0.02

0.02

8.66

8.67

8.38

8.01

7.97

8.22

Ani

sotr

opy

= 7.

8%

Ani

sotr

opy

= 1.

9%

561

N =

507

Ol:

319(

63%

)D

i: 18

8(37

%)

569

N =

692

Ol:

548(

79%

)D

i: 14

4(21

%)

570

N =

872

Ol:

723(

83%

)D

i: 14

9(17

%)

Weh

rlit

e

Ani

sotr

opy

= 8.

4%

Figure4.

(Con

tinued)


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much more water than olivine (120–760 ± 100 ppmH/Si and1320–7690 ± 100 ppm H/Si, respectively) in the lherzolites(samples 565-1, 565-2, and 568). In addition, the coexistingdiopside in the wehrlites (samples 561, 569, and 570) alsocontained much more water than olivine (1060–3970 ± 100 ppm H/Si).

5. Discussion and implications

5.1. LPOs of olivine

5.1.1. Type-B olivine LPO

We found type-B olivine LPO in the lherzolites frommantle xenoliths in Shanwang (eastern China). The pro-posed mechanisms for producing type-B olivine LPO arewater-induced fabric transition (Jung and Karato 2001a;Katayama et al. 2004; Jung et al. 2006), melt-induced slipchange (Holtzman et al. 2003), and the pressure effect onthe deformation of olivine at high pressure (>3 GPa; Junget al. 2009b; Ohuchi et al. 2011; Raterron et al. 2011).However, the samples with type-B LPOs in this studyshowed no melt, and are spinel lherzolites originatingfrom a shallow depth of less than about 60 km.Therefore, the possibility of melt segregation and a pres-sure effect can be ruled out for the production of type-Bolivine LPOs. On the other hand, the water content ofolivine in the lherzolites (samples 565-1, 565-2, and 568)was 60–80 ± 30 ppm H/Si but that of coexisting pyroxenes(Opx and Cpx) in the samples was much higher than thatof olivine: 120–760 ± 100 ppm H/Si for Opx and 1320–7690 ± 100 ppm H/Si for Cpx. This discrepancy betweenthe water content of olivine and pyroxene is considered tobe due to a markedly higher OH diffusion rate for olivinethan for pyroxene (Peslier and Luhr 2006). The high watercontent of coexisting pyroxenes in the Shanwang xenolithsindicates that olivine originally contained much morewater than the current estimation, considering the partitioncoefficient (DCpx/Ol) of water between olivine and Cpx inprevious experimental studies (Aubaud et al. 2004; Hauriet al. 2006). Our FTIR data are consistent with a study ofNushan peridotite xenoliths in the Eastern Block (Yanget al. 2008), in which olivine contained 0–10 wt ppm H2O(0–170 ppm H/Si) and both Opx and Cpx contained muchmore water: 2–40 wt ppm H2O (30–670 ppm H/Si) and 2–100 wt ppm H2O (30–1670 ppm H/Si), respectively. SinceYang et al. (2008) used the calibration of Bell et al.(2003), the water content above had already been con-verted to Paterson’s calibration by dividing by 3.5 tocompare with our data. In addition, the estimated stresses

Table 2. Seismic anisotropies of P- and S-waves for olivine, Opx, Cpx, and whole rock.

Sample

Olivine Opx Cpx Whole rock1

AVp (%) Max. AVs (%) AVp (%) Max. AVs (%) AVp (%) Max. AVs (%) AVp (%) Max. AVs (%)

561 11.6 7.53 – – 2.1 1.81 7.8 5.18565-1 10.5 6.79 2.0 2.02 6.4 4.34 7.1 4.20565-2 11.1 7.42 1.2 1.53 5.3 3.18 8.2 5.34568 7.6 6.30 2.3 2.46 4.4 2.93 5.7 4.54569 9.5 6.70 – – 5.3 3.03 8.4 5.70570 2.2 1.93 – – 5.8 6.57 1.9 2.48

Note: 1The seismic anisotropy of whole rock was calculated following the analysed modal compositions of each sample in Table 1. AVp: maximumseismic anisotropy of P-wave, AVs: seismic anisotropy of S-wave.

10 µm

(a)

5 µm

(b)

Figure 5. Backscattered electron (BSE) images showing dislo-cation microstructures of samples for (a) type-E LPO (sample561) and (b) type-B LPO (sample 565-1) of olivine. (a) Well-developed subgrain boundaries were observed in a large fractionof the grains. (b) Straight dislocations and few subgrain bound-aries were observed.


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for lherzolites with type-B fabric in our study are relativelyhigh (~50 MPa) in nature (Katayama et al. 2005; Skemeret al. 2006; Jung 2009). Consequently, we consider thatthe formation of type-B olivine LPO is most likely due towater at high stress.

5.1.2. Type-E olivine LPO

We also found type-E olivine LPO in the wehrlites in ourstudy. The proposed mechanisms for producing type-Eolivine LPO are a pre-existing mechanical anisotropy onthe mantle lithosphere (Michibayashi and Mainprice 2004)and the deformation of olivine in the presence of a mod-erate amount of water at low stress (Mehl et al. 2003;Katayama et al. 2004; Jung et al. 2006; Harigane et al.2013). Michibayashi and Mainprice (2004) showed thattype-A LPO (the crystallographic [100] axes of olivine arealigned subparallel to the lineation, and the [010] axes arealigned subnormal to the foliation) of olivine, which wasformed by E–W mantle flow, was transformed to type-Eolivine LPO due to the NW–SE strike-slip shear.Therefore, they emphasized the importance of initialmechanical anisotropy, which can control later structuralbehaviour of the lithosphere. Olivine LPO in our study isthought to have been changed from type-B in the early tolate Mesozoic to type-E in the late Mesozoic to Cenozoic.However, this change cannot be explained by the simplerotation of initial mechanical anisotropy due to late exten-sion in the E–W direction. According to a previous experi-mental study (Katayama et al. 2004; Jung et al. 2006), type-Efabric was found under low stress (

LPO with a slip system of (100)[001], and anhydrousaluminous enstatite showed type-BC LPO with a slipsystem of (010)[001]. However, the enstatite in theShanwang xenoliths has been reported as a MgSiO3-enstatite by geochemical analysis (Zheng et al. 1998,2005a, 2005b, 2006; Zhang et al. 2007; Chu et al. 2009;Xiao et al. 2010; Xiao and Zhang 2011), and we observedone sample (568) with type-AC enstatite LPO and twoother samples (565-1 and 565-2) with type-BC LPO,which is not consistent with the experimental results ofManthilake et al. (2013). As a result, we need furtherstudy to understand the mechanism for producing enstatiteLPO. In addition, we classified four different types of LPOof diopside to find the relationship between fabrics andvarious geological components such as stress, water con-tent, and modal composition of rock, to understand themechanism for producing diopside LPOs. However, wefound no relationship and further study is required tounderstand LPO formation for diopside.

5.3. Relationship between fabric strength of mineralsand seismic anisotropy

The correlation between seismic anisotropy and fabric(LPO) strength (J- or M-index) has been reported in pre-vious studies for olivine (Ben Ismaı̈l and Mainprice 1998;Mainprice et al. 2000; Skemer et al. 2005; Jung et al.2009a) and enstatite (Jung et al. 2010). These previousresults indicate that the seismic anisotropy of P-wave(AVp) and the maximum S-wave anisotropy (Max. AVs)increase with an increase in the fabric strength (J- orM-index) of minerals. The increasing trends of seismicanisotropy versus J-index of olivine, however, are not lin-ear, with different rates of increase for different axes ([100],[010], and [001] in olivine) (Ben Ismaı̈l and Mainprice1998). In contrast, the increasing trend of seismic aniso-tropy versus the M-index of olivine is linear, with an almostidentical increasing rate for any axes and all LPO types ofolivine in experimentally deformed samples (Skemer et al.2005). We compared the seismic anisotropies of P- and S-wave with the M-index for each mineral in our samples,and plotted these against previous data of olivine andenstatite in naturally deformed samples (Jung et al. 2009a,2010) (Figure 6). In the case of the olivine of different LPOtypes, seismic anisotropies of P and S-wave increased withincreasing M-index. However, the increasing rate is shownas curvilinear rather than linear (Figure 6), similar to find-ings from a previous report (Mainprice et al. 2000) wherethe J index was used. In the case of enstatite and diopside,there are also tendencies for increase in both P-wave andmaximum S wave anisotropy with an increase in the M-index, but increasing rates were lower than that of olivine(Figure 6). As a result, our data suggest that the seismicanisotropy of whole rock composed of olivine, enstatite,

and diopside would be lower than that of olivine only, asmentioned in Section 4.2.

5.4. Thickness of anisotropic layer under the study area

Most of the seismic anisotropy of shear waves is consid-ered to be related to the upper mantle, and we thereforeconsidered that the mantle peridotite xenoliths can be usedto interpret these anisotropic structures. Indeed, Zhao andXue (2010) indicated that the observed seismic anisotropybeneath the Sino-Korean craton is primarily caused byshear wave splitting from the upper mantle. Following aprevious study (Pera et al. 2003) where four differentgeodynamic models for the origin of seismic anisotropyin central Italy were considered (including upwelling, lat-eral shear, horizontal extension, and tilted slab) (Figure 7),we calculated the thickness of the anisotropic layer underthe study area for each model (Figure 8 and Table 4) usingboth the delay time from shear wave splitting (delay timeof 0.8 ± 0.26 s; Zhao and Xue 2010) beneath the EasternBlock of the Sino-Korean craton and the S-wave seismic

Vp

An

iso

tro

py

(%)

M-index

(a)

0

2

4

6

8

10

12

14

16

0 0.05 0.1 0.15 0.2 0.25 0.3

Ol type-B

Ol type-E

Opx

Cpx

Ol J2009-A

Ol J2009-D

Opx J2010

(b)

Max

. AV

s A

nis

otr

op

y (%

)

M-index

0

1

2

3

4

5

6

7

8

9

0 0.05 0.1 0.15 0.2 0.25 0.3

Ol type-B

Ol type-E

Opx

Cpx

Ol J2009-A

Ol J2009-D

Opx J2010

Figure 6. Seismic anisotropy compared to the fabric (LPO)strength (M-index) of minerals. (a) P-wave (Vp) seismic anisotropyfor each mineral. (b) Maximum S-wave seismic anisotropy (max.AVs) for each mineral. Ol, olivine; Opx, enstatite; and Cpx, diopside.J2009-A and J2009-D: data for type-A and -D olivine LPO, respec-tively, from Jung et al. (2009a). J2010: data from Jung et al. (2010).


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velocity and anisotropy from the LPOs of minerals in oursamples (Figure 3). The thickness (T) of the anisotropiclayers can be described as follows (Pera et al. 2003):

T ¼ 100� δ� ð Þ=AVs; (3)

where δ is the delay time of the S-wave, < Vs > is theaverage velocity of fast and slow shear wave velocities(Vs1 and Vs2), and AVs is the seismic anisotropy of the S-wave expressed as a percentage. As indicated byEquation (3), the thickness of the anisotropic layer canbe influenced by the average velocity of Vs1 and Vs2when the delay time and AVs are fixed; the thickness ofthe anisotropic layer increases with increasing averagevelocity. In addition, we separately calculated the requiredthickness of the anisotropic layer for lherzolite samples(565-1, 565-2, and 568) and for wehrlite samples (561,569, and 570) based on the volume fraction of olivine,because they showed different types of LPO and it wasconsidered that the lherzolite had become wehrlite viametasomatism of the upper mantle lithosphere (Xiaoet al. 2010; Xiao and Zhang 2011).

As a result, the thicknesses of the anisotropic layer fromthe LPOs of lherzolite samples were estimated to be in therange 80–125, 90–125, 310–680, and 160–290 km for theupwelling, lateral shear, horizontal extension, and tilted slabmodels, respectively; while those from the LPOs of wehrlitesamples were estimated to be in the range of 230–415, 180–190, 125–140, and 140–190 km, respectively (Table 4).Owing to the thin lithospheric thickness of the EasternBlock (currently ~80–110 km; Griffin et al. 1998a; Chen

et al. 2006, 2008; Sodoudi et al. 2006; Zhao et al. 2009), itcan most likely be interpreted that the lherzolite sampleshave been deformed by either upwelling or a lateral shearmode, but the wehrlite samples have been deformed by ahorizontal extension mode.

Because many studies have indicated that lithosphericthinning by metasomatic melts occurred during the LateMesozoic to the Cenozoic (Griffin et al. 1998a; Zhenget al. 1998, 2001, 2005a, 2006; Zheng and Lu 1999; Fanet al. 2000; Gao et al. 2002; Zhang 2005; Ying et al. 2006;Zhang et al. 2007, 2008, 2010, 2011; Xiao et al. 2010;Xiao and Zhang 2011), it is possible that the mantlelherzolite xenoliths may have recorded the previous defor-mation fabric (i.e. the subduction of the South Chinacraton beneath the Sino-Korean craton during theMesozoic). To consider the geodynamic mechanism ofmantle flow during the Mesozoic E–W trend collision,we attempted to calculate the required thickness of theanisotropic layer for lherzolite samples (565-1, 565-2,and 568). We used the delay time from shear wave split-ting (delay time of 1.5 ± 0.26 s; Zhao and Xue 2010)beneath the Western Block of the Sino-Korean craton,because this block has a thick Archaean or Proterozoiclithosphere (~200 km) which is considered to be equiva-lent to the previous thickness of the Eastern Block beforethe occurrence of lithospheric thinning (Griffin et al.1998a; Zheng et al. 1998, 2001; Chen et al. 2006, 2008;Sodoudi et al. 2006; Zhang et al. 2008; Zhao et al. 2009;Zhao and Xue 2010). Consequently, we estimated theanisotropic layer thickness for the upwelling, lateralshear, horizontal extension, and tilted slab models to be

SKS vertical

X

Y

Z

S-wave polarization direction

(c) Horizontal extension

X

Z

Y

SKS vertical


(d) Tilted slab

X

YZ


SKS vertical

(a) Upwelling

X

Y

Z

SKS vertical


(b) Lateral shear

Figure 7. Four different geodynamic models for the origin of seismic anisotropy (modified after Pera et al. 2003): (a) upwelling, (b)lateral shear, (c) horizontal extension, and (d) tilted slab. The plane shaded grey represents the foliation.


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in the range 145–240, 165–235, 535–1270, and 290–545 km, respectively. This result indicates that the lherzo-lite samples might have been deformed by lateral shearmode, because the required thickness of this model is inaccord with the thickness of the thick lithosphere.

5.5. Implications for seismic anisotropy

In previous studies, type-B olivine LPO in nature hasgenerally been found in subduction zones (Skemer et al.

2006; Tasaka et al. 2008; Jung 2009), and the trench-parallel seismic anisotropy of the fast shear wave in themantle wedge has been attributed to type-B olivine LPO(Jung and Karato 2001a; Nakajima and Hasegawa 2004;Kneller et al. 2005; Long and van der Hilst 2005, 2006;Nakajima et al. 2006; Karato et al. 2008). On the otherhand, type-E olivine LPO shows similar seismic signaturesto that of type-A, which has a Vs1 polarization directionparallel to the mantle flow (Jung et al. 2006). Therefore,type-E olivine LPO can be also considered to demonstrateseismic anisotropy in the upper mantle, as can type-A(Montagner and Tanimoto 1990, 1991; Katayama et al.2004; Jung et al. 2006; Karato et al. 2008; Jung 2009).

The study area, Shanwang, has located at the front ofthe continental-collisional subduction zone between theSino-Korean craton and the South China craton, and hassimultaneously lain astride the Tan-Lu fault zone. Since theTan-Lu fault zone is considered to be a syn-orogenic sinis-tral strike-slip fault (Yin and Nie 1993; Jiawei and Guang1994; Li 1994; Fletcher et al. 1995; Gilder et al. 1999; Zhuet al. 2004; Zhang et al. 2012), many studies have indicatedthat this syn-orogenic fault zone might play an importantrole as a major melt-infiltrating channel from the astheno-sphere into the lithospheric mantle beneath the easternSino-Korean craton during the Mesozoic and Cenozoic(Zheng et al. 1998, 2001, 2005a, 2006; Fan et al. 2000;Gao et al. 2002; Zhang 2005; Ying et al. 2006; Zhang et al.2007, 2010, 2011; Xiao et al. 2010; Xiao and Zhang 2011).There is a possibility that the lithospheric mantle wasdeformed under wet conditions, as suggested by the highwater content of constituent minerals (Opx and Cpx) inxenoliths (in Section 5.1.1) beneath Shanwang. Becausethe Tan-Lu fault zone was a strike-slip fault until the lateMesozoic (Zhu et al. 2004; Zhang et al. 2012), the forma-tion of type-B olivine LPO in the lherzolite can most likelybe interpreted to have been formed by lateral shear due tosyn-orogenic strike-slip fault during/after the continental-collisional subduction between the Sino-Korean craton and

Olivine volume fraction (%)

50 60 70 80 90 10040

80

640

1280

160

320

Shanwang peridotite xenoliths

delay time 0.8 ± 0.26 s

Opx

Opx

OpxOpx

Cpx

Cpx

Cpx

Cpx

Upwelling(X direction)

Lateral shear(Y direction)

Horizontal extension(Z direction)

Lherzolite (Type-B)

Subduction(tilt 60 deg.)

(a)

Olivine volume fraction (%)

Th

ickn

ess

(km

)T

hic

knes

s (k

m)

50 60 70 80 90 10040

80

640

1280

160

320

Shanwang peridotite xenoliths

delay time 0.8 ± 0.26 s

Cpx

Cpx

Cpx

Cpx

Upwelling(X direction)

Lateral shear(Y direction)

Horizontal extension(Z direction)

Wehrlite (Type-E)

Subduction(tilt 60 deg.)

(b)

Figure 8. The relationship between olivine volume fraction andthe required thickness of the anisotropic layer (log scale) neededto explain seismic anisotropy for (a) lherzolite and (b) wehrlite.The large open and solid squares represent the mean compositionof lherzolite and wehrlite, respectively. The grey shaded arearepresents the range of modal composition of Shanwang perido-tite xenoliths from this study.

Table 4. Thickness of anisotropic layer in eastern Chinacalculated using four different geodynamic models: upwelling,lateral shear, horizontal extension, and tilted slab.

Geodynamicmodels

Thickness of anisotropic layer (km)1

Lherzolite(type-B Ol)

Wehrlite(type-E Ol)

Upwelling 80–125 (±30) 230–415 (±100)Lateral shear 90–125 (±30) 180–190 (±60)Horizontal extension 310–680 (±120) 125–140 (±40)Tilted slab 160–290 (±60) 140–190 (±50)

Lithospheric thicknessof eastern China

~200 km for or Proterozoic,~80–110 km for current

Note: 1The thickness of the anisotropic layer was calculated using thedelay time from the shear wave splitting beneath eastern China (delaytime = 0.80 ± 0.26 s; Zhao and Xue 2010).


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the South China craton (i.e. movement in the N–S to NNE–SSW direction). This interpretation is consistent with theresults of our calculation (Section 5.4). Type-B LPO can beused to explain the trench-parallel E–W- to WNW–ESE-trending polarization directions of the fast shear wave in theEastern Block of the Sino-Korean craton (near theShanwang area) (Figure 9(a) and (b)).

In contrast, it is suggested that the direction of absoluteplate motion (APM) was changed from a N–S to an E–Wtrend by the westward-subducting Pacific plate beneath theEurasian plate during the late Mesozoic to Cenozoic, andby movement of the stagnant slab of the subducted Pacificplate, which is considered to reach the boundary betweenthe Central Zone and the Eastern Block of the Sino-Koreancraton (Ai and Zheng 2003; Huang and Zhao 2006; Zhaoet al. 2007a; Zhu and Zheng 2009; Chen 2010). In addition,because the Tan-Lu fault zone also changed from strike-slipto extensional fault at that time (Zhang et al. 2012), theformation of type-E olivine LPO in the wehrlites can mostlikely be interpreted to have been formed in the horizontalextension mode. Type-E olivine LPO can be used to inter-pret a Vs1 polarization direction subparallel to the currentaverage APM of the Sino-Korean craton (Gripp and

Gordon 2002) (Figure 9(c) and (d)). This model is consis-tent with a previous hybrid model of mantle flow where thesubduction of the Pacific plate causes a mantle wedge flowand an extension in the Eastern Block (Zhao and Xue 2010;Zhao et al. 2011, 2013). The latter authors also proposedthe relatively huge upwelling at the Central Zone. However,our study is limited to the Eastern Block in Shanwangregion. As a result, further study on the LPO of mineralsin mantle xenoliths derived from beneath the Central Zoneis needed.

6. Conclusion

Deformation microstructures, including the LPOs of oli-vine, enstatite, and diopside in mantle xenoliths (inShanwang, eastern China), were studied to further under-stand the deformation mechanism and seismic anisotropyof the upper mantle. In this study, we found two types ofolivine LPO: type-E in wehrlites and type-B in spinellherzolites. In addition, we found two types of enstatiteLPO (type-BC and type-AC) and four different types ofdiposide LPO. Observations of strong LPOs, and the

(b) Early to late Mesozoic

N SSino-Korean craton South China craton

Lithosphere

Mantle flow

[001]

[100][010]

Type-B

(d) Late Mesozoic – Cenozoic

EWSino-Korean craton

W B E BC Z

Stagnant slab of Pacific plate

Lithosphere

Mantle flow

Type-E [001]

[010]

[100]

(a) Early to late Mesozoic

1 sec

Sino-Korean craton

South China craton

W B C Z E B

N

(c) Late Mesozoic – Cenozoic

1 sec

Sino-Korean craton

South China craton

W B C Z E B

N

Figure 9. Schematic diagram for the evolution of the lithosphere beneath the Eastern Block of the Sino-Korean craton. (a) and (b) Earlyto late Mesozoic; (c) and (d) late Mesozoic to Cenozoic. (a) and (c) The polarization directions of fast shear waves are indicated by blackbars (modified after Zhao and Xue 2010) and green bars (modified after Zhao and Zheng 2005). The thick black arrows indicate directionsof plate motion. Absolute plate motion in (c) is after Gripp and Gordon (2002).


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numerous dislocations in olivine, suggest that samplesshowing both type-B and -E LPOs were deformed indislocation creep. Seismic anisotropy calculated using theLPO of minerals showed that the seismic anisotropy ofolivine was stronger than that of both enstatite and diop-side. Furthermore, the thickness of the anisotropic layerwas calculated for four different geodynamic end modelsto understand the origin of seismic anisotropy beneath thestudy area. As a result, we suggest that seismic anisotropyunder the study area can most likely be explained by twodeformation modes that might have occurred at differenttimes: one mode deformed lherzolites with a type-B oli-vine LPO by lateral shear during/after the period ofMesozoic continental collision between the Sino-Koreanand South China cratons, while the other deformed thewehrlites with a type-E olivine LPO by horizontal exten-sion during the period of change in APM in relation to thewestward-subducting Pacific plate.

AcknowledgementsThe calculations of seismic anisotropy were made using theprogrammes of David Mainprice (http://www.gm.univ-montp2.fr/spip/spip.php?rubrique179). H.J. thanks Professor GwanghaiShi and Professor Youngwoo Kil for their help in collectingsamples at Shanwang. We thank Weidong Sun, JohnWakabayashi, Robert J. Stern, Ikuo Katayama, and two anony-mous reviewers for the thoughtful and constructive comments.

FundingThis work was supported by the Mid-career ResearchProgramme through an NRF grant funded by the MEST [grantnumber 3345-20130011] in Korea.

Supplemental dataSupplemental data for this article can be accessed at http://dx.doi.org/10.1080/00206814.2014.928240.

ReferencesAbramson, E.H., Brown, J.M., Slutsky, L.J., and Zaug, J., 1997,

The elastic constants of San Carlos olivine to 17 GPa:Journal of Geophysical Research: Solid Earth (1978–2012),v. 102, no. B6, p. 12253–12263. doi:10.1029/97JB00682.

Ai, Y., and Zheng, T., 2003, The upper mantle discontinuitystructure beneath eastern China: Geophysical ResearchLetters, v. 30, no. 21, 2089, SDE 4, p. 1–5. doi:10.1029/2003GL017678.

Aubaud, C., Hauri, E.H., and Hirschmann, M.M., 2004,Hydrogen partition coefficients between nominally anhy-drous minerals and basaltic melts: Geophysical ResearchLetters, v. 31, no. 20, L20611, p. 1–4. doi:10.1029/2004GL021341.

Bai, Q., and Kohlstedt, D.L., 1992, High-temperature creep ofolivine single crystals, 2 dislocation structures:Tectonophysics, v. 206, no. 1–2, p. 1–29. doi:10.1016/0040-1951(92)90365-D.

Bell, D.R., Rossman, G.R., Maldener, J., Endisch, D., andRauch, F., 2003, Hydroxide in olivine: A quantitative deter-mination of the absolute amount and calibration of the IRspectrum: Journal of Geophysical Research: Solid Earth(1978–2012), v. 108, no. B2, 2105, ECV 8, p. 1–9.doi:10.1029/2001JB000679.

Ben Ismaϊl, W., and Mainprice, D., 1998, An olivine fabricdatabase: An overview of upper mantle fabrics and seismicanisotropy: Tectonophysics, v. 296, no. 1–2, p. 145–157.doi:10.1016/S0040-1951(98)00141-3.

Brenker, F.E., Prior, D.J., and Müller, W.F., 2002, Cation order-ing in omphacite and effect on deformation mechanism andlattice preferred orientation (LPO): Journal of StructuralGeology, v. 24, no. 12, p. 1991–2005. doi:10.1016/S0191-8141(02)00010-X.

Brey, G.P., and Khler, T., 1990, Geothermobarometry in four-phaselherzolites II New thermobarometers, and practical assessmentof existing thermobarometers: Journal of Petrology, v. 31, no. 6,p. 1353–1378. doi:10.1093/petrology/31.6.1353.

Bystricky, M., Kunze, K., Burlini, L., and Burg, J.-P., 2000, Highshear strain of olivine aggregates: Rheological and seismicconsequences: Science, v. 290, no. 5496, p. 1564–1567.doi:10.1126/science.290.5496.1564.

Carter, N.L., and Ave’Lallemant, H.G., 1970, High temperatureflow of dunite and peridotite: Geological Society of AmericaBulletin, v. 81, no. 8, p. 2181–2202. doi:10.1130/0016-7606(1970)81[2181:HTFODA]2.0.CO;2.

Chai, M., Brown, J.M., and Slutsky, L.J., 1997, The elasticconstants of an aluminous orthopyroxene to 12.5 GPa:Journal of Geophysical Research: Solid Earth (1978–2012),v. 102, no. B7, p. 14779–14785. doi:10.1029/97JB00893.

Chang, L.J., Wang, C.Y., and Ding, Z.F., 2009, Seismic aniso-tropy of upper mantle in eastern China: Science in ChinaSeries D: Earth Sciences, v. 52, no. 6, p. 774–783.doi:10.1007/s11430-009-0073-4.

Chen, L., 2010, Concordant structural variations from the surfaceto the base of the upper mantle in the North China craton andits tectonic implications: Lithos, v. 120, no. 1–2, p. 96–115.doi:10.1016/j.lithos.2009.12.007.

Chen, L., Tao, W., Zhao, L., and Zheng, T., 2008, Distinct lateralvariation of lithospheric thickness in the Northeastern NorthChina craton: Earth and Planetary Science Letters, v. 267,no. 1–2, p. 56–68. doi:10.1016/j.epsl.2007.11.024.

Chen, L., Zheng, T., and Xu, W., 2006, A thinned lithosphericimage of the Tanlu Fault Zone, eastern China: Constructedfrom wave equation based receiver function migration:Journal of Geophysical Research, v. 111, no. B9,p. B09312. doi:10.1029/2005JB003974.

Christensen, N.I., and Lundquist, S.M., 1982, Pyroxene orienta-tion within the upper mantle: Geological Society of AmericaBulletin, v. 93, no. 4, p. 279–288. doi:10.1130/0016-7606(1982)932.0.CO;2.

Chu, Z.-Y., Wu, F.-Y., Walker, R.J., Rudnick, R.L., Pitcher, L.,Puchtel, I.S., Yang, Y.-H., and Wilde, S.A., 2009, Temporalevolution of the lithospheric mantle beneath the easternNorth China craton: Journal of Petrology, v. 50, no. 10, p.1857–1898. doi:10.1093/petrology/egp055.

Collins, M.D., and Brown, J.M., 1998, Elasticity of an uppermantle clinopyroxene: Physics and Chemistry of Minerals, v.26, no. 1, p. 7–13. doi:10.1007/s002690050156.

Fan, W.M., Zhang, H.F., Baker, J., Jarvis, K.E., Mason, P.R.D.,and Menzies, M.A., 2000, On and off the North Chinacraton: Where is the Archaean keel?: Journal of Petrology,v. 41, no. 7, p. 933–950. doi:10.1093/petrology/41.7.933.


Dow

nloa

ded

by [

Seou

l Nat

iona

l Uni

vers

ity]

at 2

2:21

21

Apr

il 20

15

http://www.gm.univ-montp2.fr/spip/spip.php?rubrique179http://www.gm.univ-montp2.fr/spip/spip.php?rubrique179http://dx.doi.org/10.1080/00206814.2014.928240http://dx.doi.org/10.1080/00206814.2014.928240http://dx.doi.org/10.1029/97JB00682http://dx.doi.org/10.1029/2003GL017678http://dx.doi.org/10.1029/2003GL017678http://dx.doi.org/10.1029/2004GL021341http://dx.doi.org/10.1029/2004GL021341http://dx.doi.org/10.1016/0040-1951(92)90365-Dhttp://dx.doi.org/10.1016/0040-1951(92)90365-Dhttp://dx.doi.org/10.1029/2001JB000679http://dx.doi.org/10.1016/S0040-1951(98)00141-3http://dx.doi.org/10.1016/S0191-8141(02)00010-Xhttp://dx.doi.org/10.1016/S0191-8141(02)00010-Xhttp://dx.doi.org/10.1093/petrology/31.6.1353http://dx.doi.org/10.1126/science.290.5496.1564http://dx.doi.org/10.1130/0016-7606(1970)81[2181:HTFODA]2.0.CO;2http://dx.doi.org/10.1130/0016-7606(1970)81[2181:HTFODA]2.0.CO;2http://dx.doi.org/10.1029/97JB00893http://dx.doi.org/10.1007/s11430-009-0073-4http://dx.doi.org/10.1016/j.lithos.2009.12.007http://dx.doi.org/10.1016/j.epsl.2007.11.024http://dx.doi.org/10.1029/2005JB003974http://dx.doi.org/10.1130/0016-7606(1982)93%3C279:POWTUM%3E2.0.CO;2http://dx.doi.org/10.1130/0016-7606(1982)93%3C279:POWTUM%3E2.0.CO;2http://dx.doi.org/10.1093/petrology/egp055http://dx.doi.org/10.1007/s002690050156http://dx.doi.org/10.1093/petrology/41.7.933

Fletcher, C.J.N., Fitches, W.R., Rundle, C.C., and Evans, J.A.,1995, Geological and isotopic constraints on the timing ofmovement in the Tan-Lu Fault Zone, northeastern China:Journal of Southeast Asian Earth Sciences, v. 11, no. 1,p. 15–22. doi:10.1016/0743-9547(94)00034-C.

Gao, S., Rudnick, R.L., Carlson, R.W., McDonough, W.F., andLiu, Y.S., 2002, Re-Os evidence for replacement of ancientmantle lithosphere beneath the North China Craton: Earthand Planetary Science Letters, v. 198, no. 3–4, p. 307–322.doi:10.1016/S0012-821X(02)00489-2.

Gifkins, R.C., 1970, Optical microscopy of metals: New York,American Elsevier, 208 p.

Gilder, S.A., Leloup, P.H., Courtillot, V., Chen, Y., Coe, R.S.,Zhao, X.X., Xiao, W.J., Halim, N., Cogné, J.P., and Zhu,R.X., 1999, Tectonic evolution of the Tancheng-Lujiang(Tan-Lu) fault via Middle Triassic to Early Cenozoicpaleomagnetic data: Journal of Geophysical Research-Solid Earth, v. 104, no. B7, p. 15365–15390.doi:10.1029/1999JB900123.

Godard, G., and van Roermund, H.L.M., 1995, Deformation-induced clinopyroxene fabrics from eclogites: Journal ofStructural Geology, v. 17, no. 10, p. 1425–1443.doi:10.1016/0191-8141(95)00038-F.

Goetze, C., and Kohlstedt, D.L., 1973, Laboratory study ofdislocation climb and diffusion in olivine: Journal ofGeophysical Research, v. 78, no. 26, p. 5961–5971.doi:10.1029/JB078i026p05961.

Griffin, W.L., Andi, Z., O’Reilly, S.Y., and Ryan, C.G., 1998a,Phanerozoic evolution of the lithosphere beneath the Sino-Korean craton, in Flower, M.F.J., Chung, S.L., Lo, C.H., andLee, T.Y., eds., Mantle dynamics and plate interactions inEast Asia: Geodynamics Series: Washington, D.C.,American Geophysical Union, v. 27, p. 107–126.

Griffin,W.L., O’Reilly, S.Y., Ryan, C.G., Gaul, O., and Ionov, D.A.,1998b, Secular variation in the composition of subcontinentallithospheric mantle, inBraun, J., Dooley, J., Goleby, B., van derHilst, R., and Klootwijk, C., eds., Structure and evolution of theAustralian continent: Geodynamics Series: Washington, D.C.,American Geophysical Union, v. 26, p. 1–26.

Gripp, A.E., and Gordon, R.G., 2002, Young tracks of hotspotsand current plate velocities: Geophysical JournalInternational, v. 150, no. 2, p. 321–361. doi:10.1046/j.1365-246X.2002.01627.x.

Harigane, Y., Michibayashi, K., Morishita, T., Tani, K., Dick, H.J., and Ishizuka, O., 2013, The earliest mantle fabrics formedduring subduction zone infancy: Earth and Planetary ScienceLetters, v. 377–378, p. 106–113. doi:10.1016/j.epsl.2013.06.031.

Hauri, E.H., Gaetani, G.A., and Green, T.H., 2006, Partitioningof water during melting of the earth’s upper mantle at H2O-undersaturated conditions: Earth and Planetary ScienceLetters, v. 248, no. 3–4, p. 715–734. doi:10.1016/j.epsl.2006.06.014.

Helmstaedt, H., Anderson, O.L., and Gavasci, A.T., 1972,Petrofabric studies of eclogite, spinel-websterite, and spi-nel-lherzolite xenoliths from kimberlite-bearing brecciapipes in Southeastern Utah and Northeastern Arizona:Journal of Geophysical Research Solid Earth, v. 77, no. 23,p. 4350–4365. doi:10.1029/JB077i023p04350.

Hidas, K., Falus, G., Szabó, C., Szabó, P.J., Kovács, I., andFöldes, T., 2007, Geodynamic implications of flattened tab-ular equigranular textured peridotites from the Bakony-Balaton Highland Volcanic field (Western Hungary):Journal of Geodynamics, v. 43, no. 4–5, p. 484–503.doi:10.1016/j.jog.2006.10.007.

Holtzman, B.K., Kohlstedt, D.L., Zimmerman, M.E.,Heidelbach, F., Hiraga, T., and Hustoft, J., 2003, Melt seg-regation and strain partitioning: Implications for seismicanisotropy and mantle flow: Science, v. 301, no. 5637,p. 1227–1230. doi:10.1126/science.1087132.

Hu, S., He, L., and Wang, J., 2000, Heat flow in the continentalarea of China: A new data set: Earth and Planetary ScienceLetters, v. 179, no. 2, p. 407–419. doi:10.1016/S0012-821X(00)00126-6.

Huang, J., and Zhao, D., 2006, High-resolution mantle tomogra-phy of China and surrounding regions: Journal ofGeophysical Research: Solid Earth: (1978–2012), v. 111,no. B9, B09305, p. 1–21. doi:10.1029/2005JB004066.

Huang, Z., Xu, M., Wang, L., Mi, N., Yu, D., and Li, H., 2008,Shear wave splitting in the southern margin of the OrdosBlock, north China: Geophysical Research Letters, v. 35, no.19, p. L19301. doi:10.1029/2008GL035188.

Iidaka, T., and Niu, F., 2001, Mantle and crust anisotropy in theeastern China region inferred from waveform splitting ofSKS and PpSms: Earth Planets and Space, v. 53, no. 3, p.159–168.

Jiawei, X.U., and Guang, Z., 1994, Tectonic models of the Tan-Lu fault zone, eastern China: International Geology Review,v. 36, no. 8, p. 771–784. doi:10.1080/00206819409465487.

Jin, L.Y., 1985, Xenoliths in Cenozoic basalts from Tanlu fault:Journal of Changchun College of Geology, v. 3, p. 21–32. [inChinese.]

Jung, H., 2009, Deformation fabrics of olivine in Val Malencoperidotite found in Italy and implications for the seismicanisotropy in the upper mantle: Lithos, v. 109, no. 3–4,p. 341–349. doi:10.1016/j.lithos.2008.06.007.

Jung, H., and Karato, S.-I., 2001a, Water-induced fabric transi-tions in olivine: Science, v. 293, no. 5534, p. 1460–1463.doi:10.1126/science.1062235.

Jung, H., and Karato, S.-I., 2001b, Effects of water on dynami-cally recrystallized grain-size of olivine: Journal of StructuralGeology, v. 23, no. 9, p. 1337–1344. doi:10.1016/S0191-8141(01)00005-0.

Jung, H., Katayama, I., Jiang, Z., Hiraga, T., and Karato, S.,2006, Effect of water and stress on the lattice-preferredorientation of olivine: Tectonophysics, v. 421, no. 1–2,p. 1–22. doi:10.1016/j.tecto.2006.02.011.

Jung, H., Lee, J., Ko, B., Jung, S., Park, M., Cao, Y., and Song,S., 2013, Natural type-C olivine fabrics in garnet peridotitesin North Qaidam UHP collision belt, NW China:Tectonophysics, v. 594, p. 91–102.

Jung, H., Mo, W., and Choi, S.H., 2009a, Deformation micro-structures of olivine in peridotite from Spitsbergen, Svalbardand implications for seismic anisotropy: Journal ofMetamorphic Geology, v. 27, no. 9, p. 707–720.doi:10.1111/j.1525-1314.2009.00838.x.

Jung, H., Mo, W., and Green, H.W., 2009b, Upper mantle seis-mic anisotropy resulting from pressure-induced slip transi-tion in olivine: Nature Geoscience, v. 2, no. 1, p. 73–77.doi:10.1038/ngeo389.

Jung, H., Park, M., Jung, S., and Lee, J., 2010, Lattice pre-ferred orientation, water content, and seismic anisotropy oforthopyroxene: Journal of Earth Science, v. 21, no. 5, p.555–568. doi:10.1007/s12583-010-0118-9.

Jung, S., Jung, H., and Austrheim, H., 2014, Characterization ofolivine fabrics and mylonite in the presence of fluid andimplications for seismic anisotropy and shear localization:Earth Planets and Space, v. 66, no. 1, p. 46, 1–21.

Kamei, A., Obata, M., Michibayashi, K., Hirajima, T., andSvojtka, M., 2010, Two contrasting fabric patterns of olivine


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http://dx.doi.org/10.1016/0743-9547(94)00034-Chttp://dx.doi.org/10.1016/S0012-821X(02)00489-2http://dx.doi.org/10.1029/1999JB900123http://dx.doi.org/10.1016/0191-8141(95)00038-Fhttp://dx.doi.org/10.1029/JB078i026p05961http://dx.doi.org/10.1046/j.1365-246X.2002.01627.xhttp://dx.doi.org/10.1046/j.1365-246X.2002.01627.xhttp://dx.doi.org/10.1016/j.epsl.2013.06.031http://dx.doi.org/10.1016/j.epsl.2013.06.031http://dx.doi.org/10.1016/j.epsl.2006.06.014http://dx.doi.org/10.1016/j.epsl.2006.06.014http://dx.doi.org/10.1029/JB077i023p04350http://dx.doi.org/10.1016/j.jog.2006.10.007http://dx.doi.org/10.1126/science.1087132http://dx.doi.org/10.1016/S0012-821X(00)00126-6http://dx.doi.org/10.1016/S0012-821X(00)00126-6http://dx.doi.org/10.1029/2005JB004066http://dx.doi.org/10.1029/2008GL035188http://dx.doi.org/10.1080/00206819409465487http://dx.doi.org/10.1016/j.lithos.2008.06.007http://dx.doi.org/10.1126/science.1062235http://dx.doi.org/10.1016/S0191-8141(01)00005-0http://dx.doi.org/10.1016/S0191-8141(01)00005-0http://dx.doi.org/10.1016/j.tecto.2006.02.011http://dx.doi.org/10.1111/j.1525-1314.2009.00838.xhttp://dx.doi.org/10.1038/ngeo389http://dx.doi.org/10.1007/s12583-010-0118-9

observed in garnet and spinel peridotite from a mantle-derived ultramafic mass enclosed in felsic granulite, theMoldanubian Zone Czech Republic: Journal of Petrology,v. 51, no. 1–2, p. 101–123. doi:10.1093/petrology/egp092.

Karato, S., 1987, Scanning electron microscope observation ofdislocations in olivine: Physics and Chemistry of Minerals, v.14, no. 3, p. 245–248. doi:10.1007/BF00307989.

Karato, S., and Lee, K.H., 1999, Stress-strain distribution indeformed olivine aggregates: Inference from microstructuralobservations and implications for texture development, inProceedings of the 12th International Conference onTextures of Materials, Montreal, Volume 2: Ottawa,National Research Council Press, p. 1546–1555.

Karato, S.-I., and Jung, H., 2003, Effects of pressure on high-temperature dislocation creep in olivine: PhilosophicalMagazine, v. 83, no. 3, p. 401–414. doi:10.1080/0141861021000025829.

Karato, S.-I., Jung, H., Katayama, I., and Skemer, P., 2008,Geodynamic significance of seismic anisotropy of the uppermantle: New insights from laboratory studies: AnnualReview of Earth and Planetary Science, v. 36, p. 59–95.doi:10.1146/annurev.earth.36.031207.124120.

Karato, S.-I., Toriumi, M., and Fujii, T., 1980, Dynamic recrys-tallization of olivine single crystals during high-temperaturecreep: Geophysical Research Letters, v. 7, no. 9, p. 649–652.doi:10.1029/GL007i009p00649.

Katayama, I., Jung, H., and Karato, S., 2004, New type of olivinefabric from deformation experiments at modest water contentand low stress: Geology, v. 32, no. 12, p. 1045–1048.doi:10.1130/G20805.1.

Katayama, I., and Karato, S., 2006, Effect of temperature on theB-to C-type olivine fabric transition and implication for flowpattern in subduction zones: Physics of the Earth andPlanetary Interiors, v. 157, no. 1–2, p. 33–45. doi:10.1016/j.pepi.2006.03.005.

Katayama, I., Karato, S., and Brandon, M., 2005, Evidence ofhigh water content in the deep upper mantle inferred fromdeformation microstructures: Geology, v. 33, no. 7, p. 613–616. doi:10.1130/G21332.1.

Kelemen, P.B., Hart, S.R., and Bernstein, S., 1998, Silica enrich-ment in the continental upper mantle via melt/rock reaction:Earth and Planetary Science Letters, v. 164, no. 1–2, p. 387–406. doi:10.1016/S0012-821X(98)00233-7.

Kneller, E.A., Van Keken, P.E., Karato, S.-I., and Park, J., 2005,B-type olivine fabric in the mantle wedge: Insights fromhigh-resolution non-Newtonian subduction zone models:Earth and Planetary Science Letters, v. 237, no. 3–4, p.781–797. doi:10.1016/j.epsl.2005.06.049.

Kohlstedt, D.L., and Goetze, C., 1974, Low-stress high-tempera-ture creep in olivine single crystals: Journal of GeophysicalResearch, v. 79, no. 14, p. 2045–2051. doi:10.1029/JB079i014p02045.

Kohlstedt, D.L., Goetze, C., and Durham, W.B., 1976a,Experimental deformation of single crystal olivine withapplication to flow in the mantle, in Strens, R.G.J., ed.,The physics and chemistry of minerals and rocks: London,John Wiley & Sons, p. 35–49.

Kohlstedt, D.L., Goetze, C., Durham, W.B., and Vander Sande,J., 1976b, New technique for decorating dislocations inolivine: Science, v. 191, no. 4231, p. 1045–1046.doi:10.1126/science.191.4231.1045.

Le Maitre, R.W., 2002, Igneous rocks: A classification and glossaryof terms: Recommendations of the International Union ofGeological Sciences, Subcommission on the Systematics of

Igneous Rocks: Cambridge, United Kingdom, CambridgeUniversity Press, 236 p.

Li, Z.X., 1994, Collision between the North and South Chinablocks: A crustal-detachment model for suturing in the regioneast of the Tanlu fault: Geology, v. 22, no. 8, p. 739–742.doi:10.1130/0091-7613(1994)0222.3.CO;2.

Liu, K.H., Gao, S.S., Gao, Y., and Wu, J., 2008, Shear wavesplitting and mantle flow associated with the deflectedPacific slab beneath northeast Asia: Journal of GeophysicalResearch: Solid Earth (1978–2012), v. 113, no. B1.doi:10.1029/2007JB005178.

Lloyd, G.E., 1987, Atomic number and crystallographic contrastimages with the SEM: A review of backscattered electrontechniques: Mineralogical Magazine, v. 51, no. 359, p. 3–19.doi:10.1180/minmag.1987.051.359.02.

Long, M.D., 2013, Constraints on subduction geodynamics fromseismic anisotropy: Reviews of Geophysics, v. 51, no. 1, p.76–112. doi:10.1002/rog.20008.

Long, M.D., and Silver, P.G., 2008, The subduction zone flowfield from seismic anisotropy: A global view: Science, v.319, no. 5861, p. 315–318. doi:10.1126/science.1150809.

Long, M.D., and Silver, P.G., 2009a, Mantle flow in subduc-tion systems: The subslab flow field and implications formantle dynamics: Journal of Geophysical Research: SolidEarth (1978–2012), v. 114, no. B10, B10312, p. 1–25.doi:10.1029/2008JB006200.

Long, M.D., and Silver, P.G., 2009b, Shear wave splitting andmantle anisotropy: Measurements, interpretations and newdirections: Surveys in Geophysics, v. 30, no. 4–5, p. 407–461. doi:10.1007/s10712-009-9075-1.

Long, M.D., and van der Hilst, R.D., 2005, Upper mantle aniso-tropy beneath Japan from shear wave splitting: Physics of theEarth and Planetary Interiors, v. 151, no. 3–4, p. 206–222.doi:10.1016/j.pepi.2005.03.003.

Long, M.D., and van der Hilst, R.D., 2006, Shear wave splittingfrom local events beneath the Ryukyu arc: Trench-parallelanisotropy in the mantle wedge: Physics of the Earth andPlanetary Interiors, v. 155, no. 3–4, p. 300–312. doi:10.1016/j.pepi.2006.01.003.

Lysak, S.V., 2009, Thermal history, geodynamics and currentthermal activity of lithosphere in China: Russian Geologyand Geophysics, v. 50, no. 9, p. 815–825. doi:10.1016/j.rgg.2009.08.007.

Mainprice, D., 1990, A FORTRAN program to calculate seismicanisotropy from the lattice preferred orientation of minerals:Computers and Geosciences, v. 16, p. 385–393. doi:10.1016/0098-3004(90)90072-2.

Mainprice, D., 2007, Seismic anisotropy of the deep earth from amineral and rock physics perspective, in Schubert, G., ed.,Treatise of geophysics: Amsterdam, Elsevier, v. 2, p. 437–491. doi:10.1016/B978-044452748-6/00045-6.

Mainprice, D., Barruol, G., and Ben Ismaïl, W., 2000, Theseismic anisotropy of the Earth’s mantle: From singlecrystal to polycrystal, in Karato, S.-i., Forte, A.,Liebermann, R., Masters, G., and Stixrude, L., eds.,Earth’s deep interior: Mineral physics and tomographyfrom the atomic to the global scale: GeophysicalMonograph Series: Washington, D.C., AmericanGeophysical Union, v. 117, p. 237–264.

Manthilake, M., Miyajima, N., Heidelbach, F., Soustelle, V., andFrost, D., 2013, The effect of aluminum and water on thedevelopment of deformation fabrics of orthopyroxene:Contributions to Mineralogy and Petrology, v. 165, no. 3,p. 495–505. doi:10.1007/s00410-012-0819-4.


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