Insights into the Tectonic Fractures in the Yanchang Formation Interbedded Sandstone-Mudstone of the Ordos Basin Based on Core Data and Geomechanical Models

The distribution and intensity of tectonic fractures within geologic units are important to hydrocarbon exploration and development. Taken the Upper Triassic Yanchang Formation interbedded sandstone-mudstone in the Ordos Basin as an example, this study used the finite element method（FEM） based on geomechanical models to study the development of tectonic fractures. The results show that the sandstones tend to generate tectonic fractures more easily than mudstones with the same layer thickness, and the highest degree of tectonic fractures will be developed when the sandstone-mudstone thickness ratio is about 5.0. A possible explanation is proposed for the tectonic fracture development based on two important factors of rock brittleness and mechanical layer thickness. Generally, larger rock brittleness and thinner layer thickness will generate more tectonic fractures. In interbedded sandstone-mudstone formations, the rock brittleness increases with the increasing mechanical layer thickness, hence, these two factors will achieve a balance for the development of tectonic fractures when the sandstone-mudstone thickness ratio reaches a specific value, and the development degree of tectonic fractures is the highest at this value.

Advances and Overview of the Study on Paleo-earthquake Events: A Review of Seismites

The distribution and formation mechanisms of typical identified seismites are analyzed based on various factors from plate tectonic positions, types of sedimentary basins and properties of seismogenic faults to focal mechanisms.Especially, structural styles, reserved positions, activity times, formation mechanisms and dynamics of soft-sediment deformation structures triggered by seismic activity are systematically analyzed.According to the genetic types of seismites, we propose 5 categories, including liquefied deformation, thixotropic deformation, hydroplastic deformation, superimposed gravity driving deformation and brittle deformation.Further, based on the main genetic types, composition of sediments and deformation styles, we draw up 35 secondary classifications.To determine paleo-seismic sequences in different times, activities of seismogenic faults, high-resolution tectonic events in one main tectonic movement and paleo-tectonic settings, and to understand the inducing mechanisms of paleo-earthquakes and ecologic environment evolution, researching on seismites are of great significance.Combing multiple approaches to identify the paleoearthquake records, simulating experiments on various soft-sediment deformation structures triggered by different magnitudes of shocking, dating precisely on paleo-seismic events, impacting on paleogeography and biological environment and on energy and resources domain are the frontiers of paleoseismic research.

Early Jurassic Soft-Sediment Deformation Interpreted as Seismites in the Wuqia Pull-Apart Basin and the Strike-Slip Talas-Ferghana Fault, Xinjiang, China

The early Jurassic soft-sediment deformation occurring within lacustrine sandstone is distributed mainly in the Wuqia region of SW Tianshan Mountains, Xinjiang, western China. Triggered by earthquakes, such deformation was found to occur in three beds overlying the lower Jurassic Kangsu Formation. The main styles of deformation structures comprise load cast, ball-and- pillow, droplet, cusps, homogeneous layer, and liquefied unconformity. The deformation layers reflect a series of three strong earthquakes at the end of early Jurassic in the Wuqia region. The differences of deformation mechanisms undergone might represent the varying magnitudes of the earthquake events. During the early Jurassic, the Wuqia region was located in a pull-apart basin controlled by the significant Talas-Ferghana strike-slip fault in central Asia, which initiated the soft-sediment deformation induced by earthquakes. Our research suggests that the paleoseismic magnitudes could have ranged from Ms 6.5 to 7.

Rock Damage Structure of the South Longmen-Shan Fault in the 2008 M8 Wenchuan Earthquake Viewed with Fault-Zone Trapped Waves and Scientific Drilling

This article is to review results from scientific drilling and fault-zone trapped waves （FZTWs） at the south Longman-Shan fault （LSF） zone that ruptured in the 2008 May 12 M8 Wenchuan earthquake in Sichuan,China.Immediately after the mainshock,two Wenchuan Fault Scientific Drilling （WFSD） boreholes were drilled at WFSD-1 and WFSD-2 sites approximately 400 m and 1 km west of the surface rupture along the Yinxiu-Beichuan fault （YBF）,the middle fault strand of the south LSF zone.Two boreholes met the principal slip of Wenchuan earthquake along the YBF at depths of 589-m and 1230-m,respectively.The slip is accompanied with a 100-200-m-wide zone consisting of fault gouge,breccia,cataclasite and fractures.Close to WFSD-1 site,the nearly-vertical slip of ～4.3-m with a 190-m wide zone of highly fractured rocks restricted to the hanging wall of the YBF was found at the ground surface after the Wenchuan earthquake.A dense linear seismic array was deployed across the surface rupture at this venue to record FZTWs generated by aftershocks.Observations and 3-D finite-difference simulations of FZTWs recorded at this cross-fault array and network stations close to the YBF show a distinct low-velocity zone composed by severely damaged rocks along the south LSF at seismogenic depths.The zone is several hundred meters wide along the principal slip,within which seismic velocities are reduced by ～30-55％ from wall-rock velocities and with the maximum velocity reduction in the ～200-m-wide rupture core zone at shallow depth.The FZTW-inferred geometry and physical properties of the south LSF rupture zone at shallow depth are in general consistent with the results from petrological and structural analyses of cores and well log at WFSD boreholes.We interpret this remarkable low-velocity zone as being a break-down zone during dynamic rupture in the 2008 M8 earthquake.We examined the FZTWS generated by similar earthquakes before and after the 2008 mainshock and observed that seismic velocities within fault core zone was reduced by ～10％ due to severe damage of fault rocks during the M8 mainshock.Scientific drilling and locations of aftershocks generating prominent FZTWs also indicate rupture bifurcation along the YBF and the Anxian-Guangxian fault （AGF）,two strands of the south LSF at shallow depth.A combination of seismic,petrologic and geologic study at the south LSF leads to further understand the relationship between the fault-zone structure and rupture dynamics,and the amplification of ground shaking strength along the low-velocity fault zone due to its waveguide effect.

Platinum-group Mineral(PGM) and Base-metal Sulphide(BMS) Inclusions in Chromitites of the Zedang Ophiolite, Southern Tibet, China and their Petrogenetic Significance

Voluminous platinum-group mineral （PGM） inclusions including erlichmanite （Os,Ru）S2, laurite （Ru,Os）S2, and irarsite （Ir, Os,Ru,Rh）AsS, as well as native osmium Os（Ir） and inclusions of base metal sulphides （BMS）, including millerite （NiS）, heazlewoodite （NiaS2）, covellite （CuS） and digenite （Cu3S2）, accompanied by native iron, have been identified in chromitites of the Zedang ophiolite, Tibet. The PGMs occur as both inclusions in magnesiochromite grains and as small interstitial granules between them; most are less than 10 ~m in size and vary in shape from euhedral to anhedral. They occur either as single or composite （biphase or polyphase） grains composed solely of PGM, or PGM associated with silicate grains. Os-, Ir-, and Ru-rich PGMs are the common species and Pt-, Pd-, and Rh-rich varieties have not been identified. Sulfur fugacity and temperature appear to be the main factors that controlled the PGE mineralogy during crystallization of the host chromitite in the upper mantle. If the activity of chalcogenides （such as S, and As） is low, PGE clusters will remain suspended in the silicate melt until they can coalesce to form alloys. Under appropriate conditions of fS2 and fO2, PGE alloys might react with the melt to form sulfides-sulfarsenides. Thus, we suggest that the Os, Ir and Ru metallic clusters and alloys in the Zedang chromitites crystallized first under high temperature and low fS2, followed by crystallization of sulphides of the laurite-erlichmanite, solid-solution series as the magma cooled and fS2 increased. The abundance of primary BMS in the chromitites suggests that fS2 reached relatively high values during the final stages of magnesiochromite crystallization. The diversity of the PGE minerals, in combination with differences in the petrological characteristics of the magnesiochromites, suggest different degrees of partial melting, perhaps at different depths in the mantle. The estimated parental magma composition suggests formation in a suprasubduction zone environment, perhaps in a forearc.

Physical Modeling of Fold-and-Thrust Belt Evolution and Triangle Zone Development:Dabashan Foreland Belt(Northeast Sichuan basin,China) as an Example

Triangle zones, generally found in foreland fold-and-thrust belts, serve as favorable objects of petroleum exploration. Taking the Dabashan foreland belt as an example, we studied the formation and development of triangle zones, and investigated the effect of d^collements and the mechanical contrast of lithology by employing the method of physical modeling. Four experimental models were conducted in the work. The results showed that ＇sand wedges＇ grew episodically, recorded by deformational length, height and slope angle. The height versus shortening rate presented an S-shape curve, and uplifting occurred successively in the direction of the foreland belt. During the formation of the triangle zone, layer-parallel shortening took place at the outset; deformation decoupling then occurred between the upper and lower brittle layers, divided by a middle-embedded silicone polymers layer. The upper brittle layers deformed mainly by folding, while the lower sand layers by thrusting. As shortening continued, the geometry of a triangle zone was altered. We consider that the triangle zone in the Dabashan foreland belt was modified from an early one based on available seismic profiles and the experimental results. In addition, dccollements and mechanical contrast impose significant influence on structural development, which can directly give rise to structural discrepancies. More d^collements and obvious mechanical contrast between brittle layers can promote the coupling between the upper and lower brittle layers. Basal d^collement controls the whole deformation and decreases the slope angle of the wedge, while roof d^collement determines whether a triangle zone can be formed.

The Deep Structure Feature of the Sichuan Basin and Adjacent Orogens

The basin-mountain system in the Sichuan Basin （SCB） reflects the main tectonic activity and the orogenic denudation in this region. The seismic probing work reveals the deep structure of the basin-mountain system. The seismic work was re-sampled to the Moho depth and the sedimentary thickness as well as the P-wave velocity=depth function to analyze the deep structure of the SCB and adjacent orogens. The results show two deposit centers in the SCB： the Deyang area in the west and the Nanchuan area in the east and depression uplift exists in the southwestern part of the SCB; the Moho shallowers gradually from the west to east （ca. 62-36 km deep）,the South-North seismic belt （SNSB） is very distinctive： the Moho depth is much shallower （〈 50 km）to the east of the SNSB, whereas it is much deeper（〉50 kin）to the west of the SNSB, suggesting that the SNSB rather than the Longmen Shan tectonic belt is a main Moho transition belt; the topography and the top interface of the basement have the same undulation trend when the sedimentary thickness and the Moho depth have a mirror relationship; the low velocity zone developed in the Kangdian thrust and fold belt and Songpan-Garze belt implied a soft, weak and thick crust there showing tectonic activity in these areas.

The Geochemical and Zircon Trace Elements Characteristics of A-type Granitoids in Boziguoer, Baicheng County, Xinjiang

The Boziguoer A-type granitoids in Baicheng County,Xinjiang,belong to the northern margin of the Tarim platform as well as the neighboring EW-oriented alkaline intrusive rocks.The rocks comprise an aegirine or arfvedsonite quartz alkali feldspar syenite,an aegirine or arfvedsonite alkali feldspar granite,and a biotite alkali feldspar syenite.The major rock-forming minerals are albite,K-feldspar,quartz,arfvedsonite,aegirine,and siderophyllite.The accessory minerals are mainly zircon,pyrochlore,thorite,fluorite,monazite,bastnaesite,xenotime,and astrophyllite.The chemical composition of the alkaline granitoids show that SiO2 varies from 64.55％ to 72.29％ with a mean value of 67.32％,Na2O＋K2O is high （9.85％-11.87％） with a mean of 11.14％,K2O is 2.39％-5.47％ （mean =4.73％）,the K2O/Na2O ratios are 0.31-0.96,Al2O3 ranges from 12.58％ to 15.44％,and total FeOT is between 2.35％ and 5.65％.CaO,MgO,MnO,and TiO2 are low.The REE content is high and the total SREE is （263-1219） ppm （mean =776 ppm）,showing LREE enrichment and HREE depletion with strong negative Eu anomalies.In addition,the chondrite-normalized REE patterns of the alkaline granitoids belong to the ＂seagull＂ pattern of the right-type.The Zr content is （113-1246） ppm （mean =594 ppm）,Zr＋Nb＋Ce＋Y is between （478-2203） ppm with a mean of 1362 ppm.Furthermore,the alkaline granitoids have high HFSE （Ga,Nb,Ta,Zr,and Hf） content and low LILE （Ba,K,and Sr） content.The Nb/Ta ratio varies from 7.23 to 32.59 （mean =16.59） and the Zr/Hf ratio is 16.69-58.04 （mean =36.80）.The zircons are depleted in LREE and enriched in HREE.The chondrite-normalized REE patterns of the zircons are of the ＂seagull＂ pattern of the left-inclined type with strong negative Eu anomaly and without a Ce anomaly.The Boziguoer A-type granitoids share similar features with A1-type granites.The average temperature of the granitic magma was estimated at 832-839℃.The Boziguoer A-type granitoids show crust-mantle mixing and may have formed in an anorogenic intraplate tectonic setting under high-temperature,anhydrous,and low oxygen fugacity conditions.

Fractal Characteristics of Fault Structures and Their Use for Mapping Ore-prospecting Potential in the Qitianling Area, Southern Hunan Province, China

Quantitative analyses of the spatial distribution of fault structures can provide a theoretical basis for forecasting prospective ore deposits. Characteristics and complexity of fault structure distribution in the Qitianling area, Southern Hunan Province, China, were quantitatively calculated and appraised by fractal and multifractal methods to evaluate the relation between fault structures and ore-prospecting potential. The results show that the lengths of faults can be modeled as multifractals. Multifractal spectra evidently reflect the characteristics of the scaling of fault structures. The box- counting dimension value （D） of fault structures is equal to 1.656, as indicates complexity of the spatial distribution of faults and favorable structural conditions for the formation of ore deposits. Moreover, the D values of sub-regions were calculated and isopleths of their fractal dimension values were plotted accordingly. Overlay analyses of isopleths of fractal dimension values and distributions of known ore deposits show that areas with the larger fractal dimension values of fault structures have more ore deposits. This spatial coupling relationship between D values and ore deposits can be used to forecast and explore other ore deposits. On the basis of complexity theory for ore-forming systems, three exploration targets with high D values were delineated as prospective ore deposits.

Application of the Material Balance Method in Paleoelevation Recovery: A Case Study of the Longmen Mountains Foreland Basin on the Eastern Margin of the Tibetan Plateau

We applied the material balance principle of the denudation volume and sedimentary flux to study the denudation-accumulation system between the Longmen Mountains （Mts.） and the foreland basin. The amount of sediment in each sedimentation stage of the basin was estimated to obtain the denudation volume, erosion thickness and deposit thickness since the Late Triassic Epoch, to enable us to recover the paleoelevation of the provenance and the sedimentary area. The results show the following： （1） Since the Late Triassic Epoch, the elevation of the surface of the Longmen Mts. has uplifted from 0 m to 2751 m, and the crust of the Longmen Mts. has uplifted by 9.8 km. Approximately 72% of the materials introduced have been denuded from the mountains. （2） It is difficult to recover the paleoelevation of each stage of the Longmen Mts. foreland basin quantitatively by the present-day techniques and data. （3） The formation of the Longmen Mts. foreland basin consisted of three stages of thrust belt tectonic load and three stages of thrust belt erosional unload. During tectonic loading stages （Late Triassic Epoch, Late Jurassic-Early Cretaceous, Late Cretaceous-Miocene）, the average elevation of Longmen Mts. was lower （approximately 700-1700 m）. During erosional unloading stages （Early and Middle Jurassic, Middle Cretaceous and Jiaguan, Late Cenozoic）, the average elevation of Longmen Mts. was high at approximately 2000-2800m.

Diamond and Recycled Mantle:A New Perspective——Introduction of IGCP 649 Project

The IGCP 649 project entitled ＂Diamonds and Recycled Mantle＂was approved by UNESCO and IUGS in March 2015.This project is led by an international team of researchers,including Prof.Yang Jingsui of Institute of Geology of CAGS（China）.

The Major Two-stage Shortening Deformation of the Northern Tibet and Tian Shan Area Since the Latest Oligocene

It seems to be progressively recognized that the stress of the India-Asia convergent front can be transferred rapidly through the southern and central Tibetan lithosphere to the northern Tibet, hence leading to the crustal thickening deformation there during or immediately after the onset of the India-Asia collision（ca.55 Ma）.This study focuses on the late Cenozoic deformation and tectonic uplift of the northern Tibet and Tian Shan area.Detailed compilations of a variety of proxy data from sediments and bedrocks suggest that the northern Tibet and Tian Shan area underwent one stage of approximately synchronous widespread contractile deformation since 25–20 Ma, which seemed to decrease at circa 18 Ma as revealed by low-temperature thermochronological data.The latest Oligocene-early Miocene was also significant basin-forming episodes when many intermontane subbasins began to receive syntectonic sedimentation in the northeastern Tibet.Subsequently, the other phase of compressional deformation began to encroach more widely into the northern Tibet and Tian Shan area in episodic steps or continuously from 16–12 Ma to present.

Elastic and Seismic Properties of Dabie-Sulu Ultrahigh Pressure Metamorphic Rocks

Lame modulus （λ） and shear modulus （μ） are among the most important, intrinsic, elastic constants of rocks. Using 7. and μ could be much more advantageous than using P- and S-wave velocities （Vp and Vs）. Here we quantified these equivalent isotropic elastic moduli for 115 representative rocks from the ultrahigh pressure （UHP） metamorphic terrane of the Dabie-Sulu orogenic belt （China） and their variations with pressure （P）, temperature （T）, density （p）, Vp, Vs and mineralogical composition. Both moduli increase nonlinearly and linearly with increasing pressure at low （〈200-300 MPa） and high （〉200-300 MPa） pressures, respectively. In the regime of high pressures, 7. and IX decrease quasi-linearly with increasing temperature with temperature derivatives dλ/dT and dμ/dT generally in the range of -10×10-3 to -1×10-3 GPa/℃. Dehydration of water-bearing minerals such as serpentine in peridotites and chlorite in retrograde eciogites results in an abrupt drop in 7. while μ remains almost unchanged. In Z-p, μ-p and 7.-IX plots, the main categories of UHP rocks can be characterized. Serpentinization leads to significant decreases in μ and 7. as serpentine has extremely low values of Z, μ and p. Eclogites, common mafic rocks （mafic gneiss, metagabbro and amphibolite）, and felsic rocks （orthogneiss and paragneiss） have high, moderate and low μ and λ values, respectively. For pyroxenes and olivines, λ increases but μ decreases with increasing Fe/Mg ratios. For plagioclase feldspars, both Z and μ exhibit a significant positive correlation with anorthite content. SiO2-rich felsic rocks and quartzites are deviated remarkably from the general trend lines of the acid-intermediate-mafic rocks in Vs-p, μ-p, λ-Vp,λ-Vs and μ-λ diagrams because quartz has extremely low λ （-8.1 GPa） and p （2.65 g/cm3） but moderate μ （44.4 GPa） values. Increasing the contents of garnet, rutile, ilmenite and magnetite results in a significant increase in the λ and μ values of the UHP metamorphic rocks. However, either λ or μ is insensitive to the compositional variations for pyralspite （pyrope-almandine-spessartine） solution series. The results provide potentially improved constraints on characterization of crustal composition based on the elastic properties of rocks and in situ seismic data from deep continental roots.

Crustal Structure of the Indus-Tsangpo Suture Zone and its Ophiolites, Southern Tibet

The 〉 2000-kin-long Indus-Tsangpo suture zone （ITSZ） in southern Tibet marks the boundary between the India and Eurasia plates and contains the remnants of the Neotethyan oceanic lithosphere, ophiolitic mé1anges,

Diamonds, Super-Reduced and Crustal Minerals in Chromitites of the Hegenshan and Sartohay Ophiolites, Central Asian Orogenic Belt, China

The Central Asian Orogenic Belt(CAOB)is a huge tectonic mélange that lies between the North China Craton and the Siberian Block.It is composed of multiple orogenic belts,continental fragments,magmatic and metamorphic rocks,suture zones and discontinuous ophiolite belts.Although the Hegenshan and Sartohay ophiolites are separated by nearly 3000 km and lie in completely different parts of the CAOB,they are remarkably similar in many respects.Both are composed mainly of serpentinized peridotite and dunite,with minor gabbro and sparse basalt.They both host significant podiform chromitites that consist of high-Al,refractory magnesiochromite with Cr#s[100Cr/(Cr+Al)]averaging<60.The Sartohay ophiolite has a zircon U-Pb age of ca.300 Ma and has been intruded by granitic plutons of similar age,resulting in intense hydrothermal activity and the formation of gold-bearing listwanites.The age of the Hegenshan is not firmly established but is thought to have formed in the Carboniferous.Like many other ophiolites that we have investigated in other orogenic belts,the chromitites in these two bodieshave abundant diamonds,as well as numerous super-reduced and crustal minerals.The diamonds are mostly,colorless to pale yellow,200-300μm across and have euhedral to anhedral shapes.They all have low carbon isotopes(δ14C=-18 to-29)and some have visible inclusions.These are accompanied by numerous super-reduced minerals such as moissanite,native elements(Fe,Cr,Si,Al,Mn),and alloys(e.g.,Ni-Mn-Fe,Ni-Fe-Al,Ni-Mn-Co,Cr-Ni-Fe,Cr-Fe,Cr-Fe-Mn),as well as a wide range of oxides,sulfides and silicates.Grains of zircon are abundant in the chromitites of both ophiolites and range in age from Precambrian to Cretaceous,reflecting both incorporation of old zircons and modification of grains by hydrothermal alteration.Our investigation confirms that high-Al,refractory chromitites in these two ophiolites have the same range of exotic minerals as high-Cr metallurgical chromitites such as those in the Luobusa ophiolite of Tibet.These collections of exotic minerals in ophiolitic chromitites indicate complex,multi-stage recycling of oceanic and continental crustal material at least to the mantle transition zone,followed by uprise and emplacement of the peridotites into relatively shallow ophiolites.

Geogenesis and Characteristics of the Western Part of the Yarlung Zangbo Ophiolites, Tibet

The ophiolites that crop out discontinuously for more than 2000 km along the Yarlung-Zangbo suture zone （YZSZ, also called the Indus-Tsangpo suture） in southern Tibet are the remnants of the Neotethyan oceanic lithosphere,

Compositional Variation and Mineral Chemistry of the Jinshajiang and Lancangjiang Serpentinites, Yunnan Province, SW China

We present the whole rock and the mineral chemical data for upper mantle peridotites from the San-Jiang region in Yunnan, SW China. These peridotites are a part of a Paleo-Tethyan ophiolite belt occurring along the Jinshajiang and Lancangjiang suture zones. All samples of the Jinshajiang and Lancangjiang ultramafic rocks are completely serpentinized. The Jinshajiang serpentinites are characterized by no relict of olivine and pyroxene, and the Cr# content of spinels is 0.32–0.49. The Lancangjiang serpentinites were collected from two different locations; the northern location which has some relict of Opx（Al2O3 is 0.13–2.2 wt%, TiO 2 is 0.004–0.057 wt% and Mg# content is 0.895–0.933） and the Cr# content of spinel is 0.26-0.55; the southern location, which has some relict of Olivine（Fo = 90–92.5 and NiO = 0.12–0.26 wt%）, and spinel Cr# ranging from 0.41 to 0.57. The whole rock geochemical and the mineral chemistry data imply that the Jinshajiang and Lancangjiang serpentinites represent abyssal peridotites residues after ~15–20% partial melting for the Jinshajiang and Lancangjiang serpentinites（south location）, and ~11–19% partial melting for the Lancangjiang serpentinites（north location）. In addition, the compositional trends of the spinel analyses of the Lancangjiang serpentinites imply that the MORB melt-peridotite interaction process played a significant role during their evolution. These processes are evidenced by an increase in Cr# with an increase in TiO 2, whereas the spinel analyses of the Jinshajiang serpentinites display an increase in Cr# with a decrease in Ti O2, indicating that the Jinshajiang serpentinites were subjected to a simple partial melting process.

Mineralogical and Geochemical Constraints on the Origin of the Ultramafic Rocks from Wuwamen Ophiolite at the Southern Margin of Middle Tianshan, Xinjiang

Wuwamen ophiolite is located at the southern margin of Middle Tianshan, Xinjiang Province. In this paper, petrology, mineralogy and geochemistry of the ultramafic rocks from Wuwamen ophiolite were studied to constrain their origin and tectonic setting. The studies will be helpful in interpreting the evolution process of the South Tianshan Ocean.

Composition and Textual Characterization of Platinum-group Mineral(PGM) in Chromites from Zedang Ophiolite in Tibet, China

Platinum-group elements （PGE） are mainly concentrated in some specific minerals known as PGMs, which commonly occur in podifbrm chromites of ophiolites. In-situ PGM assemblages in chromites can provide valuable information on the physico-chemical nature of the parental melt（s） from which chromitite crystallized （Melcher et al., 1997）, and used as a significant petrogenetic indicator.

Petrological, Geochemical and the Origin of the Cuobuzha Peridotite in the Western Yarlung Zangbo Suture Zone

Ophiolites are fragments of ancient oceanic lithosphere emplaced onto continental margins, accretionary prisms, or island arcs during plate collisions （Dilek and Fumes, 2011）. The well-preserved ophiolitic sequence provides important information on melt extraction, melting,