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| 1 | The ages of U-Pb and Sm-Nd for eclogite from the western segment of Altyn Tagh tectonic belt——Evidence for existence of Caledonian orogenic root显示文摘The eclogites of Altyn Tagh tectonic belt occur as lens within gneisses characterized by amphibolite-facies mineral parageneses. The well-preserved eclogite is selected for Sm-Nd and U-Pb isotopic dating. The Sm-Nd isotopic data yield a whole rock-garnet-omphacite isochron of (500 ?10) Ma. The U-Pb isotopic measurements of zircons show that the four | Jianxin Zhang Zeming Zhang Zhiqin Xu Jingsui Yang Junwen Cui | 1999 | Chinese Science Bulletin1999，44，24： | 46 |
| 2 | Ages and Compositions of the Precambrian High-grade Basement of the Qilian Terrane and Its Adjacent Areas显示文摘Based on geological, chronological, geochemical and Nd isotopicstudies of the high-grade basement of the Qilian terrane, the authors have drawn the following main conclusions: (1) the high-grade basement of the Qilian terrane consists mainly of meta-argillo-arenaceous rocks and granites and its bulk part was formed in the period of 0.8-1.0 Ga (the Jinningian period); (2) most of the meta-argillo-arenaceous rocks and granitic rocks have strong negative Eu and Ba anomalies (Eu/Eu*= 0.47-0.71 and Ba/Ba*= 0.16-0.64), with tDM and εNd (1.0 Ga) ranging from 1.87 to 2.26 Ga and from -8.54 to -4.06 respectively, showing relatively high maturity; and (3) the Jinningian granitic rocks are a typical product of continent-continent collision, being probably related to the formation of the supercontinent Rodinia. These studies, com bined with the study of high-grade basement rocks near the Qilian terrane, suggest that before the Jinningian period, the Qilian-Qaidam northern-margin terrane and Dunhuang-Alxa terrane were separated from each other, belonging to differ ent plate systems of the North China craton and Yangtze platform respectively. The Qilian orogenic belt was the same as or similar to the Qiling orogenic belt in terms of the geological evolution history at least before the Jinningian period. | WAN Yusheng, XU Zhiqin, YANG Jingsui and ZHANG Jianxin Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037 | 2001 | Acta Geologica Sinica(English Edition)2001，75，4： | 40 |
| 3 | Evidence for UHP metamor-phism of eclogites from the Altun Mountains显示文摘Ultrahigh pressure (UHP) metamorphism refers to metamorphism that has occurred at pressures for the stability of coesite. The polycrystalline quartz inclusions showing the characteristic texture within garnets of eclogites indicates the pre-existence of coesites under the peak meta-morphic condition. The unusual exsolution textures in om-pacites and apatites, and the pressure estimations of phengite-bearing eclogites have been taken to provide further proof of eclogite formation under the UHP conditions. Combined with the fact that coesites have been observed in country rocks of eclogites in North Qaidam Mountains, another UHP metamorphic belt cut by the large-scale strike-slip fault in the Altun-North Qaidam area of China is confirmed. | Jianxin Zhang Jingsui Yang Zhiqin Xu Fancong Meng Haibing Li Rendeng Shi | 2002 | Chinese Science Bulletin2002，47，9： | 33 |
| 4 | Discovery of eclogite at northern margin of Qaidam Basin,NW China显示文摘Eclogite was first discovered at the northern margin of the Qaidam Basin in this study. It occurs as pods in the gneiss sequence of Middle to Upper Proterozoic age and is mainly composed of garnet, omphacite, phengite and rutile. The garnets contain 44%-62% of almandine, 15%-33% of grossular and 12%-30% of pyrope molecules, and the omphacites contain 40%-46% of jadeite. Applying garnet_clinopyroxene thermometry and jadeite geobarometry, the peak conditions of eclogite facies metamorphism occurred at about (722±123)℃ and at the pressure of up to c. 22 ×10 8 Pa. | Jingsui Yang Zhiqin Xu Haibing Li Cailai Wu Junwen Cui Jianxin Zhang Wen Chen | 1998 | Chinese Science Bulletin1998，43，20： | 34 |
| 5 | Eclogitic metapelites in the western segment of the north Qaidam Mountains:Evidence on'in situ'relationship between eclogite and its country rock显示文摘In Yuka-Luofengpo area of the north Qaidam Mountains, eclogitic metapelites are recognized. The metapelites enclosed lenses of eclogites, and locally intercalated with eclogites. Their typical mineral assemblages are garnet + kyanite + chloritoid + phengite + quartz + rutile. Strong growth zoning is preserved in garnets of metapelites, and phengite contains up to 3.4 Si per formula units. The petrographic observations and textural relations testify to the following sequence of mineral assemblages connected to three metamorphic stage: Qtz. Applying THERMOCALC Program, Grt-Phe thermometer and Grt-Ky-Phe-Qtz barometry, P-T conditions for three metamorphic stages were obtained: P=1.07±0.31GPa, T=564±22°C (prograde stage); P=2.3-3.1GPa, T=615-700°C(peak stage); and P=1.22 ± 0.26GPa, T=581± 20°C (retrograde stage). A hairpin shape P-T path similar to that of adjacent eclogite is inferred. In combination with eclogitic mineral relics in marbles and orthogneisses enclosing eclogites, we thought that the relationship between eclogites and country rocks is 'in situ' rather than 'tectonic emplacement'. | ZHANG Jianxin MENG Fancong YANG Jingsui | 2004 | Science China Earth Sciences2004，47，12： | 20 |
| 6 | Diamonds and Other Exotic Minerals Recovered from Peridotites of the Dangqiong Ophiolite, Western Yarlung-Zangbo Suture Zone, Tibet显示文摘Various combinations of diamond, moissanite, zircon, quartz, corundum, rutile, titanite, almandine garnet, kyanite, and andalusite have been recovered from the Dangqiong peridotites. More than 80 grains of diamond have been recovered, most of which are pale yellow to reddish-orange to colorless. The grains are all 100-200 μm in size and mostly anhedral, but with a range of morphologies including elongated, octahedral and subhedral varieties. Their identification was confirmed by a characteristic shift in the Raman spectra between 1325 cm^(-1) and 1333 cm^(-1), mostly at 1331.51 cm^(-1) or 1326.96 cm^(-1). Integration of the mineralogical, petrological and geochemical data for the Dongqiong peridotites suggests a multi-stage formation for this body and similar ophiolites in the Yarlung-Zangbo suture zone. Chromian spinel grains and perhaps small bodies of chromitite crystallized at various depths in the upper mantle, and encapsulated the UHP, highly reduced and crustal minerals. Some oceanic crustal slabs containing the chromian spinel and their inclusion were later trapped in suprasubduction zones(SSZ), where they were modified by island arc tholeiitic and boninitic magmas, thus changing the chromian spinel compositions and depositing chromitite ores in melt channels. | XIONG Fahui YANG Jingsui ROBINSON Paul T. XU Xiangzhen BA Dengzhu LI Yuan ZHANG Zhongming RONG He | 2016 | Acta Geologica Sinica(English Edition)2016，90，2： | 20 |
| 7 | Geological and chronological evidence of Indo-Chinese strike-slip movement in the Altyn Tagh fault zone显示文摘A set of granitic and amphibole mylonite are exposed in the Altyn Tagh fault zone. The preliminary study shows that these rocks are the product of the syntectonic anatexis in the process of the left-lat- eral strike-slip shear, and are the result of the ductile transpression. There are two types of zircon sorted from the mylonite formed with syn-shear anatexis. Among them, one is the anatectic long co-lumnar zircon and another is the residual metamorphic sub-rounded columnar zircon. Two groups of age for single zircon measured by ion microprobe (SHRIMP) are obtained: one is 461-547 Ma for the sub-rounded columnar residual metamorphic zircon, and the other is 239-244 Ma for the long-columnar anatectic zircon. This type of zircon is direc-tionally spread in rock, and the long axis direction of its crystal is identical to that of stretching lineation, represent-ing the direction of tectonic stress in the process of the strike-slip. 40Ar-39Ar age of the directional growth horn-blende in the same mylonite | LI Haibing YANG Jingsui XU Zhiqin WU Cailai WAN Yusheng SHI Rendeng Juhn G.Liou P.Tapponnier Trevor R.Ireland | 2002 | Chinese Science Bulletin2002，47，1： | 18 |
| 8 | Zircon SHRIMP dating of granite from Qaidamshan,NW China显示文摘Zircon SHRIMP dating from Qaidamshan granite shows that the granite age is 446 Ma, similar to that of eclogite in the UHP belt. We think that both granite and eclogite may be formed at different stages during tectonic evolution of this area. Together with other studies we suggested that the collision of ocean and continent plates may occur at the early Caledonian in this area, forming the eclogite, and the collision of continent and continent plates at the late Caledonian, forming the Qaidanishan granite with the zircon SHRIMP age of 446 Ma. | WU Cailai YANG Jingsui J.Wooden J.G.Liou LI Haibing SHI Rending MENG Fancong H.Persing A.Meibom | 2002 | Chinese Science Bulletin2002，47，5： | 13 |
| 9 | High- and Ultrahigh-pressure Metamorphism and Retrogressive Textures of Gneiss in the Donghai Area——Evidence from gneisses in drillhole ZK2304显示文摘In the gneisses from the drillhole ZK2304 of the Donghai area, there have been preserved high- and ultrahigh-pressure metamorphic mineral assemblages, a series of complicated retrogressive textures and relevant metamorphic reactions. In addition to garnet, jadeititic-clinopyroxene and rutile, other peak stage (M2) minerals in some gneisses include phengite, aragonite and coesite or quartz pseudomorphs after coesite. The typical peak-stage mineral assemblages in gneisses are characterized by garnet + jadeitic-clinopyroxene + rutile + coesite, garnet + jadeitic-clinopyroxene + phengite + rutile ± coesite and garnet + jadeitic-clinopyroxene + aragonite + rutile ± coesite. The grossular content (Gro) in garnet is high and may reach 50. 1 mol%. The SiO2 content of phengite ranges from 54.37% to 54.84% with 3.54-3.57 p.f.u. Quartz pseudomorphs after coesite occur as inclusions in garnet.The gneisses of the Donghai area have been subjected to multistage recrystallization and exhibit a closewise P-T | LIU Fulai, XU Zhiqin, XU Huifen and YANG Jingsui Institute of Geology, CAGS, 26 Baiwanzhuang Rd., Beijing 100037 Zhu Xiling | 1999 | Acta Geologica Sinica(English Edition)1999，73，3： | 12 |
| 10 | Mineral inclusions of zircon and UHP metamorphic evidence from paragneiss and orthogneiss of pre-pilot drill-hole CCSD-PP2 in north Jiangsu Province,China显示文摘Coesite inclusions, together with omphacite, jadeite, garnet and phengite inclusions, were identified in zircons separates from almost all gneissic core samples of pre-pilot drillhole CCSD-PP2 by the Laser Raman spectros-copy and the cathodoluminescence method. These data indicate that gneissic rocks consisting of paragneisses and or-thogneisses ubiquitously experienced UHP metamorphism. This research may be of great significance for an in-depth study of the subduction-exhumation mechanism of the Sulu UHP metamorphic belt and selecting the drilling site for the Chinese Continental Scientific Drilling Project. | LIU Fulai XU Zhiqin YANG Jingsui S Maruyama J.G.Liou I.Katayama H.Masago | 2001 | Chinese Science Bulletin2001，46，12： | 12 |
| 11 | Finding of high-pressure mafic granulites in the Amdo basement,central Tibet显示文摘High-pressure mafic granulites with a peak mineral assemblage of garnet + clinopyroxene + rutile + quartz were found in the Amdo basement,central Tibet. Two kinds of symplectites were identified that are composed of orthopyroxene + plagioclase ± spinel and hornblende + plagioclase around garnet,which were interpreted to develop during the retrogressing stages in the granulites. P-T estimates suggested that peak metamorphic conditions were about 860-920°C and 1.46-1.56 GPa,which retrogressed from post-peak phase at 820-890°C and 0.88-1.15 GPa to amphibolite facies at 550-670°C and 0.52-0.65 GPa. These three stages define a clockwise P-T path with near-isothermal decompression and cooling following the peak high-pressure metamorphism. This suggests that the Amdo granulites underwent an initial subduction to a deep crustal level of ~50 km and then were rapidly exhumed to a shallow crustal level (~20 km). The formation of Amdo granulites is considered to result from the arc-continent collision between the Amdo basement and the Qiangtang terrane in the middle Jurassic,which is a crucial step to the tectonic evolution of the Tibetan Plateau. | ZHANG XiaoRan SHI RenDeng HUANG QiShuai LIU DeLiang CIDAN SuoLang YANG JingSui DING Lin | 2010 | Chinese Science Bulletin2010，55，32： | 12 |
| 12 | Crustal Structure of the Indus-Tsangpo Suture Zone and its Ophiolites, Southern Tibet显示文摘The>2000-km-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 mélanges,flysch units and continental rocks.Field-based structural analyses and drill core observations from the | XU Zhiqin DILEK Yildrim YANG Jingsui LIANG Fenghua LIU Fei BA Dengzhu CAI Zhihui LI Guangweia DONG Hanwen | 2015 | Acta Geologica Sinica(English Edition)2015，89，A02： | 10 |
| 13 | Indosinian Orogenesis in the Lhasa Terrane, Tibet: New Muscovite ^(40)Ar-^(39)Ar Geochronology and Evolutionary Process显示文摘Muscovite 40 Ar-39 Ar dating of muscovite-quartz schist, eclogite and retrograde eclogite indicates an Indosinian orogenesis occurred at 220-240 Ma in the Lhasa terrane, which is caused by the closure of Paleo-Tethyan ocean basin and the following collision of the northern Lhasa terrane and southern Gondwana land. This Indosinian orogenesis is further confirmed by the regional sedimentary characteristics, magmatic activity and ophiolite mélange. This evidence suggests that the Indosinian orogenic belt in the Lhasa terrane is widely distributed from the Coqen county in the west, and then extends eastward through the Ningzhong and Sumdo area, finally turning around the eastern Himalayan syntaxis into the Bomi county. Based on the evolutionary process, the geological development of Lhasa terrane from early Paleozoic to early Mesozoic can be divided into seven stages. All of the seven stages make up a whole Wilson circle and reveal a perfect evolutionary process of the Paleo-Tethys ocean between the northern Lhasa terrane and southern Gondwana land. The Indosinian orogenisis is a significant event for the evolution of the Lhasa terrane as well as the Tibetan Plateau. | LI Huaqi XU Zhiqin YANG Jingsui TANG Zhemin | 2012 | Acta Geologica Sinica(English Edition)2012，86，5： | 10 |
| 14 | Luobusaite:A New Mineral显示文摘A group of mantle minerals including about 70-80 subtypes of minerals are discovered from a podiform chromitite in Tibet,China.Recovered minerals include diamond,coesite,moissanite,wustite,Fe-silides and a new mineral,luobusaite.All of these minerals were hand-picked from heavy-mineral separates of the podiform chromitite in the mantle peridotite of an ophiolite.The grains of luobusaite are as host mineral with inclusions of native silicon or as an intergrowth with native silicon and Fe-Si phase.Luobusaite occurs as irregular grains,with 0.1-0.2 mm in size,consisting of very fine-grained aggregates.The mineral is steel-grey in color,metallic luster,and opaque.The empirical formula(based on 2 for Si)is Fe0.83Si2,according to the chemical compositions of luobusaite.X-ray powder-diffraction data:orthorhombic system,space group Cmca,a = 9.874(14)?,b = 7.784(5)?,c= 7.829(7)?,Z=16. | BAI Wenji SHI Nicheng FANG Qingsong LI Guowu XIONG Ming YANG Jingsui RONG He | 2006 | Acta Geologica Sinica(English Edition)2006，80，5： | 10 |
| 15 | Discovery and Significance of Diamonds and Moissanites in Chromitite within the Skenderbeu Massif of the Mirdita Zone Ophiolite,West Albania显示文摘In recent years diamonds and other unusual minerals(carbides,nitrides,metal alloys and native elements) have been recovered from mantle peridotites and chromitites(both high-Cr chromitites and high-Al chromitites) from a number of ophiolites of different ages and tectonic settings.Here we report a similar assemblage of minerals from the Skenderbeu massif of the Mirdita zone ophiolite,west Albania.So far,more than 20 grains of microdiamonds and 30 grains of moissanites(SiC) have been separated from the podiform chromitite.The diamonds are mostly light yellow,transparent,euhedral crystals,200~300 μm across,with a range of morphologies;some are octahedral and cuboctahedron and others are elongate and irregular.Secondary electron images show that some grains have well-developed striatums.All the diamond grains have been analyzed and yielded typical Raman spectra with a shift at ~1325 cm^(-1).The moissanite grains recovered from the Skenderbeu chromitites are mainly light blue to dark blue,but some are yellow to light yeUow.All the analyzed grains have typical Raman spectra with shifts at 766 cm^(-1),787 cm^(-1),and 967 cm^(-1).The energy spectrums of the moissanites confirm that the grains are composed entirely of silicon and carbon.This investigation expands the occurrence of diamonds and moissanites to Mesozoic ophiolites in the Neo-Tethys.Our new findings suggest that diamonds and moissanites are present,and probably ubiquitous in the oceanic mantle and can provide new perspectives and avenues for research on the origin of ophiolites and podiform chromitites. | WU Weiwei YANG Jingsui MA Changqian MILUSHI Ibrahim LIAN Dongyang TIAN Yazhou | 2017 | Acta Geologica Sinica(English Edition)2017，91，3： | 10 |
| 16 | Geochronology and petrogenesis of the mafic dykes from the Purang ophiolite:Implications for evolution of the western Yarlung-Tsangpo suture zone,southwestern Tibet显示文摘The>2000 km Indus-Yarlung Tsangpo suture zone(IYSZ)is composed of the Neo-tethys oceanic remnants,flysch units and related continental rocks,which has been regarded as the boundary between the Eurasian and Indian terranes.Among the ophiolitic complexes,the Purang ophiolite is the biggest massif in the IYSZ,and many studies have been conducted on this ophiolite.However,previous studies have mainly focused on harzburgite,clinopyroxenite and dunite.Field observations show that mafic dykes were emplaced within the Purang ophiolite.However,petrogenetic evolutions of those mafic dykes are poorly understood.In this study,we present new LA-ICP-MS zircon U-Pb dating results,whole-rock geochemistry and Sr-Nd-Hf isotope analyses for microgabbro,gabbro and dolerite dykes from the Purang ophiolite of the southwestern IYSZ,respectively.Three samples yielded zircon U-Pb ages of144.2±2.1 Ma.127.9±2.3 Ma and 126.5±0.42 Ma,suggesting two different phases of magmatic activities distinctly.Whole-rock geochemical results suggest that the gabbro samples show alkaline features marked by enrichments of light rare earth elements(LREE)and large-ion lithophile elements(LILE),as well as Nb-Ta elements,suggesting an oceanic island basalt-like(OIB-like)geochemical affinity.However,the dolerite and microgabbro samples demonstrate sub-alkaline characteristics with normal mid-oceanic ridge basalt-like(N-MORB-like)geochemical features.Three distinct mafic dykes show significant Rb element depletion.The geochemical data and Sr-Nd-Hf isotopic features suggest that the microgabbro and gabbro rocks were derived from a depleted mantle that had been metasomatized by partial melts of sediments and enriched slab-derived fluids.The dolerite was also originated from a depleted mantle marked by significantly depleted Sr-Nd-Hf compositions,which was not influenced by enriched slab-derived fluids and sediments contamination during subsequent evolution.The isotope and geochemical data and tectonic diagrams suggest a tectonic transition from a within-plate to a midoceanic ridge basalt-like(MORB-like)setting during the period from ca.144 Ma to 127 Ma.Combined with regional background and this study,we propose that these mafic dykes were formed in an oceanic back-arc basin setting.Additionally,integrated with previous studies,we suggest that the geodynamic evolution of the southwestern and central parts of the Neo-Tethys oceanic basin is comparable in Early Cretaceous. | Fahui Xiong Yuanku Meng Jingsui Yang Zhao Liu Xiangzhen Xu Alireza Eslami Ran Zhang | 2020 | Geoscience Frontiers2020，11，1： | 10 |
| 17 | Determination of the Altyn Tagh strike-slip fault basin and its relationship with mountains显示文摘A special extended basin topography is developed in the middle segment of the Altyn Tagh Fault Zone. The ratio of its length to width is over 50. The long boundaries at the two sides of the basin are controlled by the straight normal faults with strike-slip component. Within the basin, the Cenozoic strata are spread. The Altyn Tagh main fault goes through the basin, and a series of strike-slip topography was formed within the basin. The reverse thrust structures were formed at the two sides of the center of the basin, thus making the geological bodies composed of old metamorphic rocks at the two sides of the basin extrude vertically, and forming the extended massif (mountain) at the sides of the basin and parallel to the basin. This special topography was called the strike-slip fault basin. The giant extended strike-slip fault basin began to form during Pliocene, and its topography was basically formed during the late Pleistocene. It is the special topography formed during the strike-slip deformation | Li Haibing Yang Jingsui Shi Rendeng Wu Cailai P.Tapponnier Wan Yusheng Zhang Jianxin Meng Fanchong | 2002 | Chinese Science Bulletin2002，47，7： | 9 |
| 18 | Diamond Discovered in High-Al Chromitites of the Sartohay Ophiolite,Xinjiang Province,China显示文摘In recent years diamonds and other exotic minerals have been recovered from mantle peridotites and high-Cr chromitites of a number of ophiolites of different age and different tectonic environments. Here we report a similar collection of minerals from the Sartohay ophiolite of Xinjiang Province,western China,which is characterized by having high-Al chromitites. Several samples of massive podiform chromitite with an aggregate weight of nearly 900 kg yielded diamonds,moissanite and other highly reduced minerals,as well as common crustal minerals. Thus far,more than 20 grains each of diamond and moissanite have been recovered from heavy mineral separates of the chromitites. The diamonds are all 100-200 μm in size and range in color from pale yellow to reddish-orange to colorless. Most of the grains are anhedral to subhedral octahedra,commonly with elongate forms exhibiting well-developed striations. They all display characteristic Raman spectra with shifts between 1325 cm-1 and 1333 cm-1,mostly 1331.51 cm-1 or 1326.96 cm-1. The moissanite grains are light blue to dark blue,broken crystals,50-150 μm across,commonly occurring as small flakes or fragments. Their typical Raman spectra have shifts at 762 cm-1,785 cm-1,and 966 cm-1. This investigation extends the occurrence of diamonds and moissanite to a Paleozoic ophiolite in the Central Asian Orogenic Belt and demonstrates that these minerals can also occur in high-Al chromitites. We conclude that diamonds and moissanite are likely to be ubiquitous in ophiolitic mantle peridotites and chromitites. | TIAN Yazhou YANG Jingsui Paul T.ROBINSON XIONG Fahui LI Yuan ZHANG Zhongming LIU Zhao LIU Fei NIU Xiaolu | 2015 | Acta Geologica Sinica(English Edition)2015，89，2： | 9 |
| 19 | Diamonds Discovered from High–Cr Podiform Chromitites of Bulqiza,Eastern Mirdita Ophiolite,Albania显示文摘Various combinations of diamond, moissanite, zircon, corundum, rutile and titanitehave been recovered from the Bulqiza chromitites. More than 10 grains of diamond have been recovered, most of which are pale yellow to reddish–orange to colorless. The grains are all 100–300 μm in size and mostly anhedral, but with a range of morphologies including elongated, octahedral and subhedral varieties. Their identification was confirmed by a characteristic shift in the Raman spectra between 1325 cm^(-1) and 1333 cm^(-1), mostly at 1331.51 cm^(-1) or 1326.96 cm^(-1). This investigation extends the occurrence of diamond and moissanite to the Bulqiza chromitites in the Eastern Mirdita Ophiolite. Integration of the mineralogical, petrological and geochemical data of the Bulqiza chromitites suggests their multi–stage formation. Magnesiochromite grains and perhaps small bodies of chromitite formed at various depths in the upper mantle, and encapsulated the ultra–high pressure, highly reduced and crustal minerals. Some oceanic crustal slabs containing the magnesiochromite and their inclusion were later trapped in suprasubduction zones, where they were modified by tholeiitic and boninitic arc magmas, thus changing the magnesiochromite compositions and depositing chromitite ores in melt channels. | XIONG Fahui YANG Jingsui ROBINSON Paul T. DILEK Yildirim MILUSHI Ibrahim XU Xiangzhen ZHOU Wenda ZHANG Zhongming RONG He | 2017 | Acta Geologica Sinica(English Edition)2017，91，2： | 9 |
| 20 | Ophiolite-Hosted Diamond: A New Window for Probing Carbon Cycling in the Deep Mantle显示文摘As reported in our prior work, we have recovered microdiamonds and other unusual minerals, including pseudomorph stishovite, moissanite, qingsongite, native elements, metallic alloys, and some crustal minerals (i.e., zircon, quartz, amphibole, and rutile) from ophiolitic peridotites and chromitites. These ophiolite-hosted microdiamonds display different features than kimberlitic, metamorphic, and meteoritic diamonds in terms of isotopic values and mineral inclusions. The characteristic of their light carbon isotopic composition implies that the material source of ophiolite-hosted diamonds is surface-derived organic matter. Coesite inclusions coexisting with kyanite rimming an FeTi alloy from the Luobusa ophiolite show a polycrystalline nature and a prismatic habit, indicating their origin as a replacement of stishovite. The occurrence in kyanite and coesite with inclusions of qingsongite, a cubic boron nitride mineral, and a high-pressure polymorph of rutile (TiO2 II) point to formation pressures of 10–15 GPa at temperatures^1300℃, consistent with depths greater than 380 km, near the mantle transition zone (MTZ). Minerals such as moissanite, native elements, and metallic alloys in chromite grains indicate a highly reduced environment for ophiolitic peridotites and chromitites. Widespread occurrence of diamonds in ophiolitic peridotites and chromitites suggests that the oceanic mantle may be a more significant carbon reservoir than previously thought. These ophiolite-hosted diamonds have proved that surface carbon can be subducted into the deep mantle, and have provided us with a new window for probing deep carbon cycling. | Dongyang Lian Jingsui Yang | 2019 | Engineering2019，5，3： | 8 |
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