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| 1 | Distinctive melt activity and chromite mineralization in Luobusa and Purang ophiolites, southern Tibet: constraints from trace element compositions of chromite and olivine显示文摘To investigate the factors controlling the mineralization in ophiolites we systematically compared the petrology and mineral compositions of the harzburgites/lherzolites, dunites and chromitites in the Luobusa and Purang ophiolites. Generally, the petrological features and trace element compositions of chromite and olivine in peridotite and chromitite are distinctly different between the two ophiolites.In Luobusa, boninitic melts are inferred to have interacted with the harzburgites and modified the distributions of some trace elements(e.g., Ni, Mn and V) in chromite and olivine. The subsequently formed dunites and chromitites experienced significant elemental exchange. In contrast, the Purang ophiolite contains a wider range of chromitite compositions and records diverse melt activities, such as the growth of relatively abundant secondary clinopyroxene. The metasomatic melts were enriched in Al and depleted in Si, Na and highly incompatible trace elements(e.g., Nb, Zr). Such melts resemble MORBlike melts proposed in the literature but are assumed to be more hydrous than typical MORB because of presence of hydrous minerals. The parental magmas of the Purang dunites and intermediate chromitites are inferred to be compositionally intermediate between boninitic and MORB-like melts. In addition,the more refractory nature of the Luobusa harzburgites facilitated a high Cr concentration gradient with the interacting melts, making it easier to increase Cr in the melts. Crystallization of clinopyroxene and amphibole in the Purang ophiolite accommodated significant amounts of Cr and water, respectively,and negatively affected Cr concentration and chromite crystallization. The concentration of chromite to form chromitites requires the presence of focused melt channels. | Benxun Su Meifu Zhou Jiejun Jing Paul T. Robinson Chen Chen Yan Xiao Xia Liu Rendeng Shi Davide Lenaz Yan Hu | 2019 | Science Bulletin2019，64，2： | 15 |
| 2 | He and Ar isotope geochemistry of pyroxene megacrysts and mantle xenoliths in Cenozoic basalt from the Changle–Linqu area in western Shandong显示文摘We performed a combined study of He–Ar isotopes and element geochemistry for pyroxene megacrysts and mantle xenoliths from Cenozoic basalt in the Changle–Linqu area in western Shandong.The results are used to trace the evolution of subcontinental lithospheric mantle after destruction of the North China Craton.The3He/4He ratios of pyroxene megacrysts,websterite,and dunites are 7.0–7.7 Ra,7.4 Ra,and 7.0–7.7 Ra,respectively.They are related to the origin of host basalts,and are slightly lower than that of mid-ocean ridge basalts(MORB).Their40Ar/36Ar ratios are much lower than that of MORB and close to that of air.The lherzolites and wehrlites represent the fragments of the newly accreted lithospheric mantle,and their REE and trace elements indicate that they experienced melt metasomatism and partial melting.The3He/4He ratios of their olivine are slightly lower than that of MORB,but3He/4He ratios of their clinopyroxene are low(2.3–7.1 Ra)and display an inverse correlation with(La/Yb)N.The40Ar/36Ar ratios of these clinopyroxene are much lower than that of MORB and close to the air ratio.Combining existing studies of petrology,Sr–Nd–Pb isotopes,O isotopes,trace elements,and Mg isotopes,we infer that the juvenile lithospheric mantle in the Changle–Linqu area was metasomatized by oceanic crust-derived melts,which transfer the supracrustal Ar isotope signatures to the mantle sources.The low4He abundance and low3He/4He ratios of clinopyroxene in the lherzolites and wehrlites are ascribed to metasomatism by crustal melts from the subducted Pacific plate. | Fei Su Yan Xiao Huaiyu He Benxun Su Ying Wang Rixiang Zhu | 2014 | Chinese Science Bulletin2014，59，4： | 6 |
| 3 | Subduction Initiation for the Formation of High-Cr Chromitites in the Kop Ophiolite, NE Turkey显示文摘The Kop ophiolite in NE Turkey,representing a forearc fragment of Neo-Tethys ocean,mainly consists of a paleoMoho transition zone(MTZ)and a harzburgitic upper mantle unit.The Kop MTZ locally contains | ZHANG Pengfei Ibrahim UYSAL ZHOU Meifu SU Benxun Erdi AVCI | 2016 | Acta Geologica Sinica(English Edition)2016，90，S1： | 6 |
| 4 | Iron Isotopic Fractionation and Origin of Chromitites in the Paleo-Moho Transition Zone of the Kop Ophiolite, NE Turkey显示文摘The Kop ophiolite in NE Turkey is a fragment of Neo-Tethyan forearc.It can be mainly divided into a paleo-Moho transition zone(MTZ)in the North and a harzburgitic mantle sequence in the South.Dunites are predominant in the MTZ of the Kop ophiolite,and they are locally interlayered with chromitites and enclose minor bodies of harzburgites near the petrological Moho boundary.Large Fe isotopic variations were observed for magnesiochromite(-0.14‰to 0.06‰)and olivine(-0.12‰to 0.14‰)from the MTZ chromitites,dunites and harzburgites.In individual dunite samples,magnesiochromite usually has lighter Fe isotopic compositions than olivine,which was probably caused by subsolidus Mg-Fe exchange between the two mineral phases.Both magnesiochromite and olivine display an increasing trend ofδ56Fe along a profile from chromitite todunite.This trend reflects continuous fractional crystallization in a magma chamber,which resulted in heavier Fe isotopes concentrated in the evolved magmas.In each cumulative cycle of chromitite and dunite,dunite was formed from relatively evolved melts after massive precipitation of magnesiochromite.Mixing of more primitive and evolved melts in the magma chamber was a potential mechanism for triggering the crystallization of magnesiochromite,generating chromitite layers in the cumulate pile.Before mixing happened,the primitive melts had reacted with mantle harzburgites during their ascendance;whereas the evolved melts may lie on the olivine-chromite cotectic near the liquidus field of pyroxene.Variable degrees of magma mixing and differentiation are expected to generate melts with differentδ56Fe values,accounting for the Fe isotopic variations of the Kop MTZ. | ZHAGN Pengfei ZHOU Meifu SU Benxun Ibrahim UYSAL Paul T.ROBINSON Erdi AVCI HE Yongsheng | 2017 | Acta Geologica Sinica(English Edition)2017，91，S1： | 3 |
| 5 | A new model for chromitite formation in ophiolites: Fluid immiscibility显示文摘Although the involvement of hydrous fluids has been widely invoked in formation of podiform chromitites in ophiolites, there is lack of natural evidence to signify the role and mechanism of fluids. In this study, a new model for the genesis of podiform chromitite is proposed on basis of revisits of comprehensive petrological, mineralogical and geochemical results of the well-preserved K?z?lda? ophiolite and the well-characterized Luobusa chromite deposit. In this model, ascending magmas intruding oceanic lithospheric mantle would presumably form a series of small magma chambers continuously connected by conduits. Tiny chromite nuclei would collect fluids dispersed in such magmas to form nascent droplets. They tend to float upward in the magma chamber and would be easily transported upward by flowing magmas. Chromite-rich droplets would be enlarged via coalescence of dispersed droplets during mingling and circulation in the magma chamber and/or transport in magma conduits. Crystallization of the chromite-rich liquid droplets would proceed from the margin of the droplet inward, leaving liquid entrapped within grains as precursor of mineral inclusions. With preferential upward transportation, immiscible chromite-rich liquids would coalesce to a large pool in a magma chamber. Large volumes of chromite would crystallize in situ, forming podiform chromitite and resulting in fluid enrichment in the chamber. The fluids would penetrate and compositionally modify ambient dunite and harzburgite, leading to significant fractionations of elemental and isotopic compositions between melts and fluids from which dunite and chromitite respectively formed. Therefore, fluid immiscibility during basaltic magma ascent plays a vital role in chromitite formation. | Benxun SU Xia LIU Chen CHEN Paul TROBINSON Yan XIAO Meifu ZHOU Yang BAI Ibrahim UYSAL Pengfei ZHANG | 2021 | Science China Earth Sciences2021，64，2： | 3 |
| 6 | Exsolution Lamellae in Olivine Grains of Dunite Units from Different Types of Mafic-Ultramafic Complexes显示文摘Exsolution microstructures in olivine grains from dunite units in a few selected tectonic environments are reported here. They include lamellae of clinopyroxene and clinopyroxene-magnetite intergrowth in the Gaositai and Yellow Hill Alaskan-type complexes, clinopyroxene-magnetite intergrowth in the K?z?lda? ophiolite, and chromite lamellae in the Hongshishan mafic-ultramafic intrusive complex. These lamellae commonly occur as needle-or rod-like features and are oriented in olivine grains. The host olivine grains have Fo contents of 92.5–92.6 in the Gaositai complex, 86.5–90.1 in the Yellow Hill complex, 93.2–93.4 in the K?z?lda? ophiolite and 86.9–88.3 in the Hongshishan complex. Clinopyroxene in the rod-like intergrowth exsolved in olivine grains in the Gaositai and Yellow Hill is diopside with similar major element compositions of Ca O(23.6–24.3 wt%), SiO_2(52.2–54.0 wt%), Al_2O_3(0.67–2.15 wt%), Cr_2O_3(0.10–0.42 wt%) and Na_2O(0.14–0.26 wt%). It falls into the compositional field of hydrothermal clinopyroxene and its origin is thus probably related to reaction between dunite and fluids. The enrichment of the fluids in Ca^(2+), Fe^(3+), Cr^(3+) and Na+, resulted in elevated concentrations of these cations in olivine solid solutions via the reaction. With decreasing temperature, the olivine solid solutions altered to an intergrowth of magnetite and clinopyroxene. The Fe^(3+) and Cr^(3+) preferentially partitioned into magnetite, while Ca^(2+) and Na+ entered clinopyroxene. Since the studied Alaskan-type complexes and ophiolite formed in a subduction environment, the fluids were probably released from the subducted slab. In contrast, the exsolved chromite in olivine grains from the Hongshishan complex that formed in post-orogenic extension setting can be related to olivine equilibrated with Cr-bearing liquid. Similarly, these lamellae have all been observed in serpentine surrounding olivine grains, indicating genetic relations with serpentinization. | LIANG Zi XIAO yan Joyashish THAKURTA SU Benxun CHEN Chen BAI Yang Patrick A. SAKYI | 2018 | Acta Geologica Sinica(English Edition)2018，92，2： | 3 |
| 7 | Characteristics and geological significance of olivine xenocrysts in Cenozoic volcanic rocks from western Qinling显示文摘从 Haoti 的新生代暴烈的岩石,西方的 Qinling 山的 Dangchang 县,包含一些地区得清楚地的橄榄石。这些橄榄石在谷物尺寸相对大并且通常有裂缝或破特征。他们的核心有类似的作文(Mg # 90.4-91.0 ) 到那些因为 peridotitic 捕虏体在暴烈的岩石和他们的边界接近的主人乘火车橄榄石斑晶的作文(Mg #=85.5-51.9) 。在这些 zoned 橄榄石的 CaO 内容比 0.1% 低。这些特征证明地区得清楚地的橄榄石从披风 periodotites 是 xenocrysts 和 disaggregated。zoned 质地是在橄榄石和主人岩浆之间的相互作用的结果。暴烈的岩石将被潜水艇 ducted 从披风来源 metasomatized 导出的可得到的数据表演改变 hydrathermally 的海洋的外壳。这些新生代暴烈的岩石的形成也许与有关快速西藏的高原高举。 | SU Benxun ZHANG Hongfu XIAO Yan ZHAO Xinmiao | 2006 | Progress in Natural Science:Materials International2006，16，12： | 2 |
| 8 | Zircon dating, Hf–Sr–Nd–Os isotopes and PGE geochemistry of the Tianyu sulfide-bearing mafic–ultramafic intrusion in the Central Asian Orogenic Belt, NW China显示文摘 | Dongmei Tang Kezhang Qin Chusi Li Liang Qi Benxun Su Wenjun Qu | 2011 | LITHOS2011，，1： | 1 |
| 9 | U- Pb Ages and Hf - O Isotopes of Zircons from Late Paleozoic Mafic-Ultramafic Units in the Southern Central Asian Orogenic Belt: Tectonic Implications and Evidence for an Early Permian Mantle Plume显示文摘 | Su Benxun Qin Kezhang Sakyi P A | 2011 | Gondwana Research2011，20，： | 1 |
| 10 | Geochronologic-Petrochemical Studies of the Hongshishan Mafic-Ultramafic Intrusion, Beishan Area, Xinjiang ( NW China):Petrogenesis and Tectonic Implications 显示文摘 | Su Benxun Qin Kezhang Sakyi P A | 2012 | International Geology Review2012，54，3： | 1 |
| 11 | Zircon Trace Element Constraints on the Evolution of the Paleoproterozoic Birimian Granitoids of the West African Craton(Ghana)显示文摘The Paleoproterozoic Birimian granitoids of the West African Craton(WAC) in the northwestern part of Ghana, have been studied for their zircon trace elements concentrations to infer the source characteristics, origin, and magmatic evolution. The zircons in the granitoids have Th/U ratios ranging from 0.03 to 1.55, and display depleted light rare earth elements(LREE) and enriched heavy rare earth elements(HREE) contents, characterized by pronounced positive to negative anomalies of Eu(Eu/Eu~*=0.14–0.98 and 1.01–6.06, respectively) and Ce(Ce/Ce~*=0.08–0.98 and 1.02–116, respectively), which may imply that they were derived from both magmatic and hydrothermal sources. The geochemical plots of U/Yb vs. Y and Hf, the positive correlation between Hf and the other high field strength elements(HFSE) and high rare earth elements(REE) contents, with enrichment in Ce and depletion in Eu, indicate that the granitoids possibly formed from partial melting of the crust. The trace elements characteristics(i.e., wide range of Hf, Ce/Ce~*, Th/U and Zr/Hf values) of the zircons suggest that crystallization of the magma occurred under variable oxidation states, which spanned over a longer period, implying that our data corroborate interpretations from studies of whole-rock geochemistry and geochronology on the granitoids of northwestern Ghana. This further indicates that the evolution of the Birimian granitoids in this part of the WAC occurred earlier than what had been reported in the literature. | Patrick Asamoah Sakyi Benxun Su Daniel Kwayisi Chen Chen Yang Bai Melesse Alemayehu | 2018 | Journal of Earth Science2018，29，1： | 1 |
| 12 | U-Pb ages and Hf-O isotopes of zircons from Late Paleozoic mafic ultramafic units in the southern Central Asian Orogenic Belt:Tectonic implications and evidence for an Early-Permian mantle plume显示文摘 | Su Benxun Qin Kezhang Sakyi P A Li Xianhua Yang Yueheng Sun He Tang Dongmei Liu Pingping Xiao Qinghua Malaviarachchi S P K | | 0，，： | 1 |
| 13 | Geological Characteristics and Metallogenic Setting of Representative Magmatic Cu-Ni Deposits in the Tianshan-Xingmeng Orogenic Belt, Central Asia显示文摘A great number of magmatic Cu-Ni deposits(including Kalatongke in Xinjiang and Hongqiling in Jilin) are distributed over a distance of almost 3000 km across the Tianshan-Xingmeng Orogenic Belt, from Tianshan Mountains in Xinjiang in the west, to Jilin in eastern China in the east. These deposits were formed during a range of magmatic episodes from the Devonian to the Triassic. Significant magmatic Cu-Ni-Co-PGE deposits were formed from the Devonian period in the Nalati arc(e.g. Jingbulake Cu-Ni in Xinjiang), Carboniferous period in the Puerjin-Ertai arc(e.g. Kalatongke Cu-Ni-Co-PGE in Xinjiang), Carboniferous period in the Dananhu-Touquan arc(e.g. Huangshandong, Xiangshan and Tulaergen in estern Tianshan, Xinjiang) to Triassic period in the Hulan arc(e.g. Hongqiling Cu-Ni in Jilin). In addition to the overall tectonic, geologic and distribution of magmatic Cu-Ni deposits in the Tianshan-Xingmeng Orogenic Belt, the metallogenic setting, deposit geology and mineralization characteristics of each deposit mentioned above are summarized in this paper. Geochronologic data of Cu-Ni deposits indicate that, from west to east, the metallogenic ages in the Tianshan-Xingmeng Orogenic Belt changed with time, namely, from the Late Caledonian(~440 Ma), through the Late Hercynian(300-265 Ma) to the Late Indosinian(225-200 Ma). Such variation could reflect a gradual scissor type closure of the paleo Asian ocean between the Siberia Craton and the North China Craton from west to east. | HAN Chunming XIAO Wenjiao SU Benxun ZHANG Xiaohui WAN Bo SONG Dongfang ZHANG Zhiyong ZHANG Jien WANG Zhongmei XIE Mingcai | 2019 | Acta Geologica Sinica(English Edition)2019，93，5： | 1 |
| 14 | “Subduction Initiation” for the Genesis of Podiform Chromite Deposits显示文摘There is a diversity of unusual minerals and mineral inclusions associated with podiform chromitites.The presence of these minerals suggests that grains of amphibolite(plagioclase,amphibole and zircon)and eclogite(coesite,kyanite and garnet)were present in the magmas from which chromite crystallized. | ZHOU Meifu ROBINSON Paul T SU Benxun GAO Jianfeng LI Jianwei YANG Jingsui MALPAS John | 2015 | Acta Geologica Sinica(English Edition)2015，89，A02： | 1 |
| 15 | High-precision potassium isotope analysis using the Nu Sapphire collision cell(CC)-MC-ICP-MS显示文摘This study presents high-precision analyses of stable potassium(K)isotope ratio using the recently-developed,collision-cell multi-collector inductively coupled plasma mass spectrometry(CC-MC-ICP-MS,Nu Sapphire).The accuracy of our analyses is confirmed by measuring well-characterized geostandards(including rocks and seawater).Our results are consistent with literature values and a precision of 0.04‰(2SD)has been achieved based on multiple measurements of BCR-2 geostandard over a six-month period.We also evaluate factors that may lead to artificial isotope fractionations,including the mismatches in K concentration and acid molarity between samples and bracketing standards,as well as potential matrices.As the K adsorption capacity of AGW50-X8(200-400 mesh)is reduced with an increasing amount of matrix elements,less than 150µg K was loaded during the column chemistry.To evaluate the potential use of K isotopes as an archive of paleo seawater composition,δ^(41)K values of an international seawater standard(IAPSO),a Mn-nodule(NOD-P-1),and two iron formation standards(FeR-2 and FeR-4)are reported.The δ^(41)K value of IAPSO is consistent with other seawater samples reported previously,further substantiating a homogeneous K isotopic distribution in modern global oceans.The K isotopes in Mn-nodule(NOD-P-1:−0.121±0.013‰)and iron formation samples(FeR-2:−0.538±0.009‰;FeR-4:−0.401±0.008‰)seem to be an effective tracer of their formation genesis and compositional changes of ancient seawater.Our results suggest that high-precision measurements of stable K isotopes can be routinely obtained and open up a large variety of geological applications,such as continental weathering,hydrothermal circulation and alteration of oceanic crust. | Wenjun LI Mengmeng CUI Qiqi PAN Jing WANG Bingyu GAO Shanke LIU Meng YUAN Benxun SU Ye ZHAO Fang-Zhen TENG Guilin HAN | 2022 | Science China Earth Sciences2022，65，8： | 1 |
| 16 | Cretaceous Meteorite Impact-Induced Initial Subduction:Records of highly Siderophile Element Abundances and Re-Os Isotopes in Ophiolites显示文摘Compiled global ophiolite data reveal that Cretaceous ophiolites exhibit broaden variations in 187Re/188Os and ^(187)Os/^(188)Os values,increases in Re concentrations and thus Re/Os ratios in all peridotites and chromitites,and additional increased PPGE/IPGE(Pd-subgroup platinum-group element(PGE)/Ir-subgroup PGE)ratios in chromitites and dunites relative to pre-Cretaceous ophiolites.These compositional changes in Cretaceous ophiolites,which mostly formed in subduction initiation settings,cannot be attributed solely to involvement of subducting or previously subducted crustal materials.Here,the author proposes a Cretaceous meteorite impact model that led to impact-induced disruption of oceanic lithosphere,asthenosphere upwelling,subduction initiation at edges of laterally spreading anomalies.High-pressure and high-temperature conditions during the impacts caused melting of the meteorites and the ambient crustal and mantle rocks,producing hybrid melts containing partially un-melted fragments.Crustal materials contributed to the elevated ^(187)Os/^(188)Os values,Re and Re/Os ratios,whereas the undifferentiated meteorite accounted for the increases in the PPGE/IPGE and decreased ^(187)Os/^(188)Os ratios.Shock pressure and super-reduced phases were likely generated by this process and were subsequently transported into the newly formed mantle peridotites and chromitites of future ophiolites.The remaining meteoritic and lithospheric fragments most likely sank deeper and were distributed widely in the convecting mantle to produce the observed global compositional heterogeneities. | Benxun Su | 2022 | Journal of Earth Science2022，33，6： | 0 |
| 17 | Constraints of Fe Isotopic Compositions on the Origin of the Luobusa Podiform Chromite Deposit, Tibet显示文摘We measured Fe isotopic compositions of mineral separates of harzburgite,dunite and chromitite from Luobusa,Tibet as well as two harzburgites from Zedang for comparison to constrain the origin of podiform chromite deposits.The olivine(Ol)and orthopyroxene(Opx)of harzburgites from both localities have δ56 Fe values | SU Benxun ZHOU Meifu XIAO Yan ZHU Bin SHI Rendeng HE Yongsheng | 2015 | Acta Geologica Sinica(English Edition)2015，89，A02： | 0 |
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