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Dur’ngoi Ophiolite in East Kunlun, Northeast Tibetan Plateau: Evidence for Paleo-Tethyan Suture in Northwest China

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Journal of China University of Geosciences 2009年第2期20卷 303-331页

作者：杨经绥史仁灯吴才来王希斌 paul T robinson Key Laboratory for Continental Dynamics of the Ministry of Land and Resources Institute of GeologyChinese Academy of Geological Sciences Department of Earth Sciences Dalhousie University

The A＇nyemaqen （阿尼玛卿） ophiolite belt along the southern margin of the East Kunlun （昆仑） Mountains marks the suture formed by the closure of paleo-Tethys. The Dur＇ngoi ophiolite in the eastern part of this belt consists of meta-peridotite, mafic-ultramafic cumulates, sheeted dikes and basaltic lavas. The meta-peridotites consist of dunite, harzburgite, lherzolite, feldspar-bearing lherzolite and garnet-bearing lherzolite and contain residual spinel with Cr# [100×Cr/（Cr＋Al）] ranging from 30 to 57 and Mg# [100×Mg/（Mg＋Fe2＋）] ranging from 50 to 75, indicating an Al- and Mg-rich series. The meta-peridotites have a relatively narrow range of composition with Mg# of 89.2-92.6, Al2O3 contents of （1-4） wt.% and slightly depleted chondrite normalized REE patterns, indicating that they represent relict mantle material that has undergone intermediate to low degrees of partial melting. Garnets in the lherzolite are andradite, enriched in Ca and Fe and depleted in Mg and AI （And=95-97, Pyr=0.3-5, Gro=0-3）, indicating a metamorphic origin. The cumulate rocks mainly consist of dunite, wehrlite, pyroxenite and gabbro. A well-layered gabbro-pyroxenite complex is defined by modal variations in plagioclase and pyroxene. Blocks of garnet-pyroxenite or rodingite are locally present in the meta-peridotites. Garnets in the cumulate rocks are grossular （Gro=69-90, And=9-19, Br=l-12）, also metamorphic origin. The diabase dikes are moderately depleted in LREE [（La/Sm）N=0.5-0.8] and HREE resulting in slightly convex chondrite-normalized patterns with slightly positive Eu anomalies （δEu=1.1-1.3）. The basaltic lavas have REE patterns similar to those of MORB with （La/Sm）N ratios of 0.5-1 and small negative Eu anomalies. They appear to have been derived from a depleted mantle source and to have undergone little or no differentiation during crystallization. SHRIMP U-Pb dating of zircons from the basalts yields 286pb/238U ages of 276-319 Ma （average 308.0±4.9 Ma）. The Dur＇ngoi ophiolite is interprete

关键词： ophiolite Dur'ngoi A'nyemaqen East Kunlun Tibet.

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Foreword

Journal of China University of Geosciences 2009年第2期20卷 205-208页

作者：杨经绥李海兵 paul T robinson Key Laboratory for Continental Dynamics of the Ministry of Land and Resouces Institute of GeologyChinese Academy of Geological Sciences Department of Earth Sciences Dalhousie University

The Qinghai-Tibet plateau is a fast uplifting area that constitutes the world＇s highest and thickest, and newest piece of continental plate which has unusual geometric configurations and landscapes. The Qinghai-Tibet plateau consists of multiple terranes, with a complex geological history, including the evo- lution of the Tethys Ocean basin, the convergence of terranes and island arcs, multiple subductions, multiple collisions and multiple orogens, over a long period of action of continental dynamic processes. Before the Indian and the Asian plates collided, during the Early Paleozoic, it was already a large orogen and terrane collision complex. As a result of the collision of the Indian and Asian plates, the fast uplift of Qinghai- Tibet plateau became the most magnificent event on the earth during the Cenozoic. It formed a vast, seemingly boundless high plateau with borders consisting of mountain chains with very high peaks, and steep gorges.

关键词： Foreword HPM high SiO ICP

Discovery of the Indosinian aluminum A-type granite in Zhejiang Province and its geological significance

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Science China Earth Sciences 2012年第1期55卷 13-25页

作者： LI WanYou MA ChangQian LIU YuanYuan paul T.robinson Faculty of Earth Sciences China University of GeosciencesWuhan 430074China 706 Geological Team Guangdong Provincial Bureau of GeologyShaoguan 512030China State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesWuhan 430074China

Zircon LA-ICP-MS U-Pb dating of the Jingju syenogranites in the southwestern part of Zhejiang Province shows that these rocks were crystallized in the Late Triassic at 215±2 Ma, rather than in the Cretaceous as previously proposed. The Jingju sy- enogranites are characterized by relatively high K2O and FeO＊, and low MgO. They have high concentrations of large ion lithophile elements （LIL） and LREE, such as K, Th, La, and Ce, but are depleted in high field strength elements （HFSE） such as Nb, Ta, and Ti. Their 104Ga/A1 ratios and （Zr＋Nb＋Ce＋Y） contents are also high. These characteristics are similar to those of A-type granites. The syenogranites have high Isr （0.7179-0.7203）, low eNa（t）（from --14.2 to --13.2）, and relatively old T2DM ages, similar to those of the ancient metamorphic basement in the Cathaysia Block. It is suggested that the Jingju syenogranites were formed by partial melting of the Cathaysia basement rocks during tectonic extension. This identification of Indosinian A-type granite in Jingju has significant implications for understanding the early Mesozoic tectonic evolution of South China.

关键词： Indosinian chronology geochemistry A-type granite Zhejiang Province

DEEP Neoarchean Subduction Indicated by Ultra-high Pressure TiO_(2)(Ⅱ) Inclusion in Ophiolitic Podiform Chromitite Block in Mélange, Central(Taihang) Orogenic Belt, North China

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Acta Geologica Sinica(English Edition) 2021年第S01期95卷 85-87页

作者： Tim KUSKY WANG Lu paul robinson Richard WIRTH HUANG Yang State Key Lab for Geological Processes and Mineral Resources Center for Global TectonicsChina University of GeosciencesWuhan 430074China Helmholtz Center Potsdam German Research Centre for Geosciences GFZ D-14473 PotsdamGermany

Understanding crust-mantle recycling through time,especially into the Archean,is crucial for understanding how the crust has grown from the mantle,and in turn how crustal material returned to the mantle alters the mantle *** of crustal material,such as C-H-O-NS-P are especially important for understanding how processes such as subduction,melting,volcanism,and the release of volatiles have regulated climate and life on Earth over billions of years.

关键词： Archean tectonics ophiolitic mélange ultrahigh-pressure minerals suduction carbon cycle

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

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Acta Geologica Sinica(English Edition) 2016年第3期90卷 900-912页

作者： GUO Guolin YANG Jingsui paul T.robinson LIU Xiaodong XU Xiangzhen XIONG Fahui State Key Laboratory Breeding Base of Nuclear Resources and Environment East China University of Technology CARMA State Key Laboratory of Continental Tectonics and Dynamics Institute of Geology Chinese Academy of Geological Sciences School of earth sciences East China University of Technology

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 suprasubdu

关键词： chromite ophiolite petrogenetic PGM Zedang

Application of the modern ophiolite concept with special reference to Precambrian ophiolites

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Science China Earth Sciences 2011年第3期54卷 315-341页

作者： Timothy M. KUSKY WANG Lu Yildirim DILEK paul robinson PENG SongBai HUANG XuYa State Key Lab for Geological Processes and Mineral Resources Three Gorges Research Center for Geohazards Ministry of Education China University of Geosciences Wuhan 430074 China Department of Geology Miami University Oxford OH 45056 USA Department of Earth Sciences Dalhousie University Halifax Nova Scotia Canada

Much has been learned in the past 40 years about the great diversity of the internal structure and geochemical compositions of Phanerozoic ophiolites, indicating that these on-land fragments of ancient oceanic lithosphere formed in distinctly different tectonic settings during their igneous evolution. Recent studies in Archean and Proterozoic greenstone belts have shown that the Precambrian rock record may also include exposures of a diverse suite of ophiolite complexes as part of craton development in the early history of the Earth. We review the salient features of the Precambrian ophiolite record to highlight what has been learned about Precambrian oceanic spreading systems since the original Penrose definition of ophiolites in 1972. Some of the diagnostic, characteristic, typical, and rare aspects of ophiolites of all ages are presented in a table in order to help determine if tectonically deformed and metamophosed sequences in Precambrian shield areas may be considered as ophiolites. The results of this comparative study are important in that they enable researchers to more realistically characterize allochthonous mafic/ultramafic rock sequences as ophiolitic or non-ophiolitic. This approach is more deterministic in contrast to some other arbitrary classification schemes requiring three or four of the Penrose-style ophiolitic units to be present in the Precambrian record for a specific rock sequence to be considered ophiolitic. Once these tectonic fragments are recognized as remnants of ancient oceanic lithosphere, great progress shall be made in understanding early Earth history. We discuss the significance and implications of the Precambrian ophiolite record to constrain the mode and nature of the plate tectonics that operated in deep time.

关键词： ophiolite Precambrian craton greenstone belt

Geochronology and Geochemistry of the Middle Proterozoic Aoyougou Ophiolite in the North Qilian Mountains,Northwestern China

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Acta Geologica Sinica(English Edition) 2001年第1期75卷 41-50页

作者： ZHANG Zhaochong MAO Jingwen ZUO Guochao YANG Jianmin paul T.robinson Institute of Geology Chinese Academy of Geological SciencesBaiwanzhuang Road 26Beijing 100037China Institute of Mineral Deposits Chinese Academy of Geological SciencesBaiwanzhuang Road 26Beijing 100037China Institute of Geology Gansu Bureau of Geology and Mineral ResourcesLanzhou 730000China Centre For Marine Geology Dalhousie UniversityHalifaxNova ScotiaB3H 3J5Canada

The Aoyougou ophiolite lies in an early Palaeozoic orogenic belt of the western North Qilian Mountains, near the Aoyougou valley in Gansu Province, northwestern China. It consists of serpentinite, a cumulate sequence of gabbro and diorite, pillow and massive lavas, diabase and chert. Ages of 1840±2 Ma, 1783±2 Ma and 1784±2 Ma on three zircons from diabase, indicate an early Middle Proterozoic age. The diabases and basalts show light rare-earth element enrichment and have relatively high TiO2 contents, characteristic of ocean island basalts. All of the lavas have low MgO, Cr, Ni contents and Mg numbers indicating a more evolved character. They are believed to have been derived from a more mafic parental magma by fractionation of olivine, Cr-spinel and minor plagioclase. Based on the lava geochemistry and regional geology, the Aoyougou ophiolite was probably believed to have formed at a spreading centre in a small marginal basin. Subduction of the newly formed oceanic lithosphere in the Middle Proterozoic produced a trench-arc-basin system, which is preserved in the North Qilian Mountains.

关键词： Proterozoic ophiolite geochronology geochemistry North Qilian Mountains

Geochemistry and zircon SHRIMP U-Pb dating of granitoids from the west segment of the North Qaidam

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Science China Earth Sciences 2009年第11期52卷 1771-1790页

作者： Joseph L.WOODEN paul T.robinson Frank K.MAZDAB Chris MATTINSON Department of Earth and Environmental Sciences Stanford University Department of Earth Sciences Dalhousie University

Granitoid intrusives such as Saishitenshan, Tuanyushan, Aolaohe and Sanchagou occur widely in the western segment of North Qaidam. All these bodies trend NW, roughly parallel to the regional structure. Zircon SHRIMP dating for these granites show that they range in age from Ordovician to Permian; 465.4±3.5 Ma for Saishitenshan, 469.7±4.6 Ma and 443.5±3.6 Ma for Tuanyushan, 372.1±2.6 Ma for Aolaohe, and 271.2±1.5 Ma and 259.9±1.2 Ma for Sanchagou. Both the Tuanyshan and Aolaohe plutons record two distinct intrusive events. Geochemically, the early Paleozoic granites have an island arc or active continental margin affinity, and their protolith may have been Mesoproterozoic oceanic crust derived from depleted mantle. The protolith of the late Paleozoic granites may have been Mesoproterozoic lower crust from the root of an island arc with the magmas reflecting a mixture of mantle and crustal material.

关键词： granitoid zircon SHRIMP U-Pb dating North Qaidam

Origin of Listwanite in the Luobusa Ophiolite,Tibet,Implications for Chromite Stability in Hydrothermal Systems

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Acta Geologica Sinica(English Edition) 2015年第2期89卷 402-417页

作者： ZHANG Lan YANG Jingsui paul T.robinson XIONG Fahui CHEN Yanhong LAI Shengmin CHEN Mei School of the Earth Sciences and Resources China University of Geosciences CARMA State Key Laboratory for Continental Tectonics and DynamicsInstitute of GeologyChinese Academy of Geological Sciences

Listwanite from the Luobusa ophiolite, Tibet, forms a narrow, discontinuous band along the eastern part of the southern boundary fault. We undertook a detailed petrographic and geochemical study to understand the mineral transformation processes and the behaviour of major and trace elements during listwanite formation. Three alteration zones characterized by distinct mineral components and texture are recognized and, in order of increasing degree of alteration, these are： zonem is rich in serpentine minerals; zonen is rich in talc and carbonates; and zone_Ⅰ is mainly composed of carbonates and quartz. Geochemical data for the three alteration zones show significant modification of some major and trace elements in the protolith, although some oxides show linear correlations with MgO. Gold mineralization is recognized in the Luobusa listwanite and may signify an important target for future mineral exploration. Gold enrichment occurs in both zone_Ⅰ and zone_Ⅱ and is up to 0.91 g/t in one sample from zonei. We show that CO_2-rich hydrothermal fluids can modify both the occurrence and composition of chromite grains, indicating some degree of chromite mobility. Low-Cr anhedral grains are more easily altered than high-Cr varieties. The compositions of chromite and olivine grains in the listwanite suggest a dunite protolith.

关键词： Listwanite mineralogy geochemistry gold mineralization chromite stability