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Trace element composition of peridotites from the southern Mariana forearc:Insights into the geochemical effects of serpentinization and/or seafloor weathering

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Chinese Journal of Oceanology and Limnology 2009年第4期27卷 985-992页

作者：汪小妹曾志刚刘长华陈俊兵殷学博王晓媛陈代庚张国良李康陈帅欧阳荷根 Key Laboratory of Marine Geology and Environment Institute of OceanologyChinese Academy of Sciences Graduate School of Chinese Academy of Sciences Geological Brigade of Hydrogeology and Engineering Geology Zhejiang Geological Prospecting Bureau

peridotites from the southern Mariana forearc were sampled on the landward trench slope of the Izu-Bonin-Mariana (IBM) subduction zone by *** mantle wedge peridotites underwent hydration by fluid derived from a dehydrated descending slab,and later interacted with seawater after emplacement at or near the *** study investigates how these two different rock-fluid interaction processes influenced trace element distribution in the southern Mariana forearc *** measured trace element concentrations of peridotites from the southern Mariana *** southern Mariana forearc peridotites are characterized by a distinct seawater-like REE pattern with an obvious negative Ce anomaly,and La shows good correlation with other REEs (except Ce).In addition,there is a great enrichment of U,Pb,Sr and Li elements,which show a distinct positive anomaly relative to adjacent elements in the multi-element *** the seawater-like REE pattern,we infer that REEs are mainly influenced by seawater during peridotite-seawater interactions after their emplacement at or near the seafloor,by serpentinization or by marine ***,the anomalous behavior of Ce,compared with other rare earth elements in these samples,may indicate that they have undergone reactions involving Ce (IV) when the peridotites interacted with *** U,Pb,Sr and Li anomalies are inferred to be related to seawater and/or fluids released during dehydration of the subducting slab.

关键词： peridotites forearc Mariana element negative Ce anomaly

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Petrology and geochemistry of serpentinized peridotites from Hahajima Seamount in Izu-Bonin forearc region

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Acta Oceanologica Sinica 2019年第11期38卷 99-110页

作者： Tuoyu Wu Liyan Tian Jinwei Gao Yanhui Dong Beijing Maiqin Nengyuan Jishu Fuwu Co.Ltd Beijing 100004China Institute of Deep-sea Science and Engineering Chinese Academy of SciencesSanya 572000China Laboratory for Marine Geology Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China Key Laboratory of Submarine Geosciences Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China

Serpentinites,which contain up to 13 wt%of water,are important reservoirs for chemical recycling in subduction *** the past two decades,forearc mantle serpentinites were identified in different locations around the ***,we present petrology and whole rock chemistry of ultramafic and mafic rocks dredged from the Hahajima Seamount,which is located 24–40 km west to the junction of the Izu-Bonin Trench and the Mariana *** all the collected samples are extensively hydrated,and olivine grains in ultramafic rocks are replaced by serpentine minerals,with only one sample preserving remaining trace of *** new results show that the Hahajima serpentinized peridotite samples are all MgO-rich(~42 wt%),but have low contents in Al2O3,CaO,rare earth and high field strength elements,which is consistent with the overall depleted character of their mantle *** calculations indicate that these Hahajima peridotite samples were derived from 10%–25%partial melting of the presumed fertile mantle source,which is generally lower than those of peridotites from Torishima Forearc Seamount,Conical Seamount and South Chamorro Seamount(mostly>25%).All the serpentinites from these four forearc seamounts show strong enrichment in fluid-mobile and lithophile elements(Li,Sr,Pb and U).In details,Hahajima Seamount serpentinites do not have obvious enrichment in Cs and Rb,and display remarkably high abundances of *** observations indicate that the serpentinization of Hahajima peridotites occurred by addition of seawater or low temperature seawater-derived hydrothermal fluid,without or with little contribution from slab-derived *** geochemical signature of serpentinites from Hahajima Seamount could be interpreted as the result of the combination of extensive partial melting and subsequent percolation of seawater through the mantle wedge.

关键词： Hahajima Seamount serpentinized peridotites IBM forearc seamounts fluid-mobile elements

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Platinum-group elements for the mantle peridotites in the Dazhuka ophiolite,Tibet,China

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Chinese Science Bulletin 2001年第3期46卷 259-264页

作者： YU Henqxiang XIA Bin MEI Houjun GUO Linzhi QI Liang TU Xianglin Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640China Institute of Geochemistry Chinese Academy of SciencesGuiyang 550002China Department of Earth Sciences Nanjing UniversityNanjing 210092China

The total PGE amounts of mantle peridotites in the Dazhuka ophiolite, Tibet, are 28.37-50.67 ng/g, slightly higher than those of mantle peridotites in the primitive mantle, and typical ophiolites in the world, and the Alps-type mantle peridotites. The PGE distribution patterns in the Dazhuka mantle peridotites are also different from those of the mantle peridotites of partial melting relict origin. The Dazhuka mantle peridotites have relatively high total PGE amounts and are enriched in Pt, Pd, and Ru. Their PGE distribution patterns belong to the positively inclined-or swallow-type patterns. The PGE distribution patterns in the mantle peridotites of partial melting relict origin belong to the negative-slope patterns or flat patterns. This reflects the unique features of the upper mantle in this region. Relative enrichment in Pt and Pd, as well as in the incompatible elements Cu, Au, Cs, Rb, Ba, Th, U and LREE, indicates that the partial melting-derived relict mantle peridotites in the Dazhuka

关键词： platinum-group elements mantle peridotites Dazhuka ophiolite Tibet.

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Geochemical Signatures of Séguéla peridotites in the West African Craton

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Journal of Geoscience and Environment Protection 2022年第12期10卷 100-116页

作者： Allialy Marc Ephrem Dicko Kagou Houssou N’guessan Nestor Kouamelan Alain Nicaise Coulibaly Yacouba Laboratory of Geology Mineral and Energy Resources (LGRME) Faculty of Earth Science and Mineral Resources Félix Houphoue&#235 t Boigny University Abidjan C&#244 te d’Ivoire

The present study deals with peridotites found in the paleo-proterozoic domain of the Leo Man Shield, Séguéla region, west-central of Côte d’Ivoire. Results show that Séguéla peridotites are composed of lherzolites, dunites and harzburgites. However, iherzolites are the most abundant. The phenocrysts in these rocks are olivine most often serpentinised, and pyroxenes, represented by diopside and enstatite. Amphiboles are divided into two groups: magmatic amphiboles and those from the destabilization of clinopyroxene. Spinels have CrO3 content which varies between 28% and 37%, Al2O3 between 33% - 41% and MgO is equal to 18%;they are poor in TiO2 and do not contain zinc oxide. Séguéla peridotites are characterised by a negative anomaly in Nb-Ta, associated with an enrichment of lithophilic elements and light rare earth elements with a fractionation rate (La/Yb) which varies between 46.22 and 150.72 and heavy rare earth elements, and HFSE depletion, which may suggest that were formed in an art context, that is, a mantle enriched by fluids from a subduction zone. However, another hypothesis could be considered, that of the interaction between the mantle and magmas in a subduction zone context.

关键词： Geochemestry peridotites Lherzolite West African Craton Séguéla Côte d’Ivoire

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Occurrence of the Pholopite-Spinel-Corundum-Sapphirine Assemblages in the Contact Between Granulites and peridotites Massif at the Beni Bousera(Morocco)

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地学前缘 2009年第S1期16卷 218-218页

作者： Barich Amel M.L.Bouybaouène Département des Sciences de la Terre Faculté des SciencesUniversité Mohamed V67

The Beni Bousera peridotite massif(Internal Rif, Morocco),5 km in width and 15 km in length,is formed in a major part of spinel-bearing lherzolite rimed by a layer of garnet-bearing peridotite(100 m thick)which is in direct contact with HP-HT granulite metamorphic rocks(16 kbar,860℃).According to recent detailed study,the shearing contact between these two formations shows the presence of serpentinite and

关键词： phlogopite corundum saphirine metasomatism peridotites Rif Morocco

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The evolution of refertilized lithospheric mantle beneath the northeastern Siberian craton:Links between mantle metasomatism,thermal state and diamond potential

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Geoscience Frontiers 2022年第6期13卷 153-169页

作者： Sergei Skuzovatov Vladislav S.Shatsky Alexey L.Ragozin Alexander P.Smelov Vinogradov Institute of Geochemistry Russian Academy of SciencesSiberian Branch1AFavorskogo Str.Irkutsk 664033Russia Sobolev Institute of Geology and Mineralogy Russian Academy of SciencesSiberian Branch3Koptyug Ave.Novosibirsk 630090Russia Geology&Geophysics Department Novosibirsk State University2 Pirogova Str.Novosibirsk 630090Russia Diamond and Precious Metal Geology Institute Russian Academy of SciencesSiberian Branch39Lenina Ave.Yakutsk 677000Russia

Although the diamond potential of cratons is linked mainly to thick and depleted Archean lithospheric keels, there are examples of craton-edge locations and circum-cratonic Proterozoic terranes underlain by diamondiferous mantle. Here, we use the results of comprehensive major and trace-element studies of detrital garnets from diamond-rich Late Triassic(Carnian) sedimentary rocks in the northeastern Siberia to constrain the thermal and chemical state of the pre-Triassic mantle and its ability to sustain the diamond storage. The studied detrital mantle-derived garnets are dominated by low-to mediumCr lherzolitic(~45%) and low-Cr megacrystic(~39%) chemistries, with a significant proportion of eclogitic garnets(~11%), and only subordinate contribution from harzburgitic garnets(~5%) with variable CrOcontents(1.2–8.4 wt.%). Low-Cr megacrysts display uniform, “normal” rare-earth element(REE)patterns with no Eu/Eu* anomalies, systematic Zr and Ti enrichment(mainly within 2.5–5), which are evidence of their crystallization from deep metasomatic melts. Lherzolitic(G9) garnets exhibit normal or humped to MREE-depleted sinusoidal REE patterns and elevated Nd/Y(up to 0.33–0.41) and Zr/Y ratios(up to 7.62). Rare low-to high-Cr harzburgitic(G10) garnets have primarily “depleted”, sinusoidal REEpatterns, low Ti, Y and HREE, but vary significantly in Zr-Hf, Ti and MREE-HREE contents, Nd/Y(within 0.1–2.4) and Zr/Y(1.53–19.9) ratios. The observed trends of chemical enrichment from the most depleted,harzburgitic garnets towards lherzolitic(including high-Ti high-Cr G11-type) garnets and megacrysts result from either voluminous high-temperature metasomatism by plume-derived silicate melts or recurrent mobilization of less voluminous kimberlitic or related carbonated mantle melts, rather than the initially primitive, fertile nature of the Proterozoic SCLM. Calculated Ni-in-garnet temperatures(primarily within ~1150–1250 ℃) indicate their derivation from at least ~220 km thick Cr-undersa

关键词： Siberian craton Kimberlite Diamond placers peridotites Eclogites Megacrysts

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Geodynamic evolution of the Tethyan lithosphere as recorded in the Spontang Ophiolite,South Ladakh ophiolites(NW Himalaya,India)

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Geoscience Frontiers 2022年第1期13卷 326-349页

作者： Mallika K.Jonnalagadda Mathieu Benoit Shivani Harshe Romain Tilhac Raymond A.Duraiswami Michel Grégoire Nitin R.Karmalkar Interdisciplinary School of Science Savitribai Phule Pune UniversityPune 411007India Department of Geology Savitribai Phule Pune UniversityPune 411007India Géosciences Environnement Toulouse CNRS-CNES-IRD-UniversitéPaul SabatierObservatoire Midi Pyrénées31400 ToulouseFrance Instituto Andaluz de Ciencias de la Tierra(IACT) CSIC–Universidad de Granada18100 ArmillaGranadaSpain Vice-Chancellor’s Office Savitribai Phule Pune UniversityPune 411007India

The Spontang Ophiolite complex represents the most complete ophiolite sequence amongst the South Ladakh ophiolites and comprises mantle rocks(depleted harzburgites,dunites and minor lherzolites)as well as crustal rocks(basalt,isotropic gabbros,layered gabbros etc.).In the present study,detailed geochemistry(whole rock as well as mineral chemistry)and Sr-Nd isotopic analyses of thirty-six ultramaficmafic samples have been attempted to constraint the evolution and petrogenetic history of the Tethyan oceanic ***,trace-element and REE patterns of the peridotites and their minerals indicate that the lherzolites experienced lower degrees of partial melting resembling abyssal peridotites(at higher temperatures,TREE=$1216℃)than the harzburgites(6%–8%versus 15%–17%).Elevated eNd(t)and variable^(87) Sr/^(86) Sr(t)ratios along with REE patterns suggest that the Spontang mafic rocks display N-MORB affinity with negligible participation of oceanic sediments in their genesis are originated from a depleted upper mantle with little contribution from subduction-related ***-type Neotethyan oceanic crust is associated with the earliest phase of subduction(of older Jurassic age)through which a younger intra-oceanic island arc(Spong arc)subsequently *** REE display typical U-shaped patterns,suggesting that these rocks have been metasomatized by LREE-enriched *** the other side,mafic rocks are characterized by heterogeneous(Nb/La)PMand(Hf/Sm)PMand relatively homogeneous eNd(t),indicating interaction of subduction-related melts with the upper mantle during the initiation of subduction,in Early Cretaceous times.

关键词： peridotites Mafic rocks Partial melting Metasomatism Ladakh

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Re-Os isotopic system and formation age of subcontinental lithosphere mantle

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Chinese Science Bulletin 2000年第3期45卷 193-200页

作者： ZHI XiachenDepartment of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China Advance Research Center for Earth Science and Astronomy, USTC, Third World Academy of Science, Hefei 230026, China Laboratory of Chemical Geodynamics, USTC, Hefei 230026, China Department of Earth and Space Sciences University of Science and Technology of China Hefei China Advance Research Center for Earth Science and Astronomy USTC Third World Academy of Science Hefei China Laboratory of Chemical Geodynamics USTC Hefei China

The determination of the formation age of subcontinental Lithosphere Mantle (SCLM) is a widely concerned issue in mantle geochemistry. it is difficult to obtain the formation age of SCLM using lithophile isotopic systems such as Rb-Sr, Sm-Nd, U-Th-Pb, ete., but as siderophile elements, the Re-Os isotopic system provides a powerful tool for that work. Here a comprehensive review on the recent development in Re-Os dating for SCLM has been given.

关键词： Re-Os isotopic dating subcontinental lithospheric mantle mantle derived peridotites Re depleted model age whole rock isochronological age.

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Effects of melt percolation on the Re-Os systematics of continental mantle lithosphere: A case study of spinel peridotite xenoliths from Heilongjiang, NE China

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Science China Earth Sciences 2012年第6期55卷 949-965页

作者： YU SongYue SONG XieYan XU YiGang CHEN LieMeng LI Jie State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry Chinese Academy of Seiences Guiyang 550002 China Key Laboratory of lsotope Geochronology and Geochemistry Guangzhou Institute ~Geochemistry Chinese Academy of Sciences Guangzhou 510640 China

Os isotope ratios of mantle peridotites have been considered to be largely immune to recent melt-rock interaction. However, Os isotope ratios and PGE (Platinum group elements) concentrations of the Yong'an xenoliths have been significantly modified by melt percolation, and are not suitable for determining the formation age of lithosphere mantle in Yong'an. In this study, the Yong'an spinel peridotite xenoliths are divided into two groups: N-Type and E-Type. The N-Type group including cpx (clinopyroxene)-poor lherzolite and harzburgite, shows a large variation of Cr#(sp) (13.2-48) and sulfur contents (from 171 ppm to below detection limit), whereas the E-Type peridotites are mainly refractory harzburgites and are characterized by high Cr#(sp) (35.3-42.2) and overall low sulfur contents (below 51 ppm). Both types show similar major and REE (rare earth element) patterns. Furthermore, the N-Type peridotites display a restricted range of iridium-group PGE (IPGE), Os/Ir and Ru/Ir ratios (Os/Ir = 0.64-1.12, Ru/Ir = 1.52-1.79) and variable palladium-group PGE (PPGE) contents (3.4-14.9 ppb), whereas the E-Type peridotites show a large variation of Os/Ir and Ru/Ir ratios (Os/Ir = 0.33-0.84, Ru/Ir = 0.94-1.6), and a restricted range of PPGE (4.3-6.9 ppb). 187Os/188Os ratios of E-Type peridotites are higher than those of N-Type peridotites at comparable fertility levels. These results suggest that N-Type peridotites may have been overprinted by metasomatism via small melt fractions, in which the percolation of the volatile-rich, small melt fractions only resulted in LILE (large ion lithophile element) enrichment of clinopyroxene, and their whole rock PGE contents and Re-Os isotope values were little changed. Moreover, E-Type peridotites may have been modified by melt-rock reaction involving relatively large melt fractions, which may result in the formation of secondary cpx and olivine and the removal of IPGE-bearing minerals such as Ru-Os-(Ir) alloys or laurite, followed by pre

关键词： peridotites highly siderophile element melt percolation sulfides NE China

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ABUNDANCE AND DISTRIBUTION OF PLATINUM-GROUP ELEMENTS (PGE) IN PERIDOTITE FROM THE DAGZHUKA OPHIOLITE IN TIBET:IMPLICATIONS FOR MANTLE METASOMATISM

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地学前缘 2000年第S1期7卷 99-100页

作者： Xia Bing 1,2 ,Yu Hengxiang 1,Mei Houjun 1,Qi Lang 2 (1 Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China 2 Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China)

Information on abundance and distribution of platinum\|group elements (PGE) in peridotite from ophiolite is relevant to understand the nature and evolution of the upper mantle. The ophiolite suite outcropping along the famous suture zone of Yarlung Zangbo River, Tibet, has attracted wide attention of geologists both in China and abroad. The Dagzhuka ophiolite of in the suture zone is thought to display a complete ophiolitic sequence. The peridotite from the Dazhuka ophiolite is composed of fairly fresh or unaltered lherzolite, harzburgite and minor dunite which are the upper mantle residuum formed by 15%～35% partial melting. In this paper we have mainly studied the abundance and distribution of PGE in the harzburgites and lherzolites. The harzburgites and lherzolites preserve total PGE contents of 28 37×10 -9 ～50 67×10 -9 respectively higher than Primitive mantle or the peridotite from some typical ophiolites and Alpine. They all have fractionated chondrite\|normalized PGE patterns with positive slopes from Ir to Pd (Fig.1), and Pd/Ir=1 13～2 40>1, Pd/Rh=2 23～7 49>1, and Pd/Pt=0 26～1 16 (average 0 67) higher than Primitive mantle (1 11, 2 35, 0 57) or CI\|chondrite (1 01, 2 73, 0 53). Consequently, the Dagzhuka peridotite are PGE\|enriched, but otherwise possess residual characteristics arising from a minimum of 15% partial melting. It is suggested that mantle residuum by partial melting have low total PGE contents, fractionated chondrite\|normalized PGE patterns with negative or slightly flat slopes from Ir to Pd, and Pd/Ir<1. But, the total PGE contents, chondrite\|normalized PGE patterns and Pt/Ir, Pd/Rh and Pd/Pt values of the Dagzhuka peridotite are completely inconsistent with a residual origin. Partial melting would have partitioned all sulfide in the source into the melt. In fact, no sulfide or silicate melt remained in the Dagzhuka peridotite. Therefore, PGE in Dagzhuka peridotite are not present in sulfides. The PGE\|enrichment and fractionation of the Dagz

关键词： platinum\|group elements(PGE) peridotites Dazhuka ophioli te Tibet

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