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Science China Earth Sciences 2009年第4期52卷 471-483页

作者： YU XinQi DI YongJun WU GanGuo ZHANG Da ZHENG Yong dai yanpei State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education China University of GeosciencesBeijing 100083China

This paper reports SHRIMP zircon U-Pb ages of 196±2 Ma for granite, and 195±1 Ma for gabbro from the Xialan complex in the Meizhou area, northern Guangdong Province. These results shed new light on the calm stage of magmatic activity in southeastern China during 200-180 Ma, and revealed that the back-arc extension induced by the subduction of the western Pacific plate may have begun at 195 Ma at least. Field observation on the fresh outcrops allows us to recognize some features formed by magma mixing. A part of the gabbro has a fine-grained rim of 20-30 cm at the margin, and thins gradually to-ward the granite; numerous dark fine-grained to microcrystalline dioritic enclaves developed in the granite. These enclaves vary in shape and size, dark minerals concentrated at the margin of enclaves, and the contact between enclaves and host rock is either obvious or obscure, or gradational. In addi-tion, needle-shaped apatites are included in the enclaves. The REE patterns of gabbros, as well as the trace element patterns, are generally consistent with those of granitic rocks. The above characters further suggest that in the Early Jurassic the injection of basic magma had melted deep continental crust and produced acidic magma, and the Xialan complex was produced by the mixing of them.

关键词： Xialan complex SHRIMP zircon U-Pb ages magma mixing the Early Jurassic Meizhou northern Guangdong Province

Steep subduction of the Indian continental mantle lithosphere beneath the eastern Himalaya revealed by gravity anomalies

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Science China Earth Sciences 2023年第9期66卷 1994-2010页

作者： Shengxian LIANG Xuben WANG Zhengwei XU yanpei dai Yonghua WANG Jing GUO Yanjie JIAO Fu LI Key Laboratory of Earth Exploration and Information Technique Chengdu University of TechnologyChengdu 610059China Chengdu Center China Geological SurveyChengdu 610081China

The geometry and deformation of the Indian continental mantle lithosphere(ICML)beneath the India-Eurasia collision zone are critical to understanding the accommodation of continent-continent *** this paper,the distribution of residual gravity anomalies in the upper mantle of southern Tibet is estimated using the gravity data and seismic velocity models,and the heterogeneous density distribution of the upper-mantle is then recovered through three-dimensional gravity *** results reveal a low-density anomaly(~300 km W-E and~100 km N-S)in the upper mantle under the eastern Himalaya,while there is no obvious density anomaly under the western *** western boundary of the low-density anomaly coincides with the Yadong-Gulu Rift(YGR)on the surface(89°–90°E),and its southern boundary is located at~28°N,approximately 130 km southward from the Indus-Yarlung suture,probably representing the mantle suture at *** observation indicates that,in contrast to the western ICML which is probably underthrusting at a shallow angle,the eastern ICML be likely subducting steeply,accompanying asthenosphere *** a laterally varying geometry suggests that a major tearing of the ICML may have taken place from the intersection of the mantle suture and the YGR in the upper *** tearing and the steep subduction of the ICML might be associated with the magmatic and mineralization events in the eastern Himalaya-Gangdese and the formation of the YGR.

关键词： Indian continental mantle lithosphere Steep subduction Mantle suture Major tearing point Upper mantle density Himalaya

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Rare earth element and yttrium compositions of the Paleoproterozoic Yuanjiacun BIF in the Lüliang area and their implications for the Great Oxidation Event(GOE)

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Science China Earth Sciences 2014年第11期57卷 2469-2485页

作者： WANG ChangLe ZHANG LianChang LAN CaiYun dai yanpei Key Laboratory of Mineral Resources Institute of Geology and Geophysics Chinese Academy of Sciences University of Chinese Academy of Sciences Guangzhou Institute of Geochemistry Chinese Academy of Sciences

In China, most Precambrian banded iron formations （BIFs） are situated in the North China Craton. The Yuanjiacun iron depos- it, located in the Ltlliang area, is arguably the most representative Superior-type BIF. This iron deposit is coherent with the sedimentary rock succession of the Yuanjiacun Formation in the lower Lliliang Group, and was interpreted to be deposited at 2.3-2.1 Ga, based on ages of overlying and underlying volcanic strata. This age overlaps with the time range of the Great Oxidation Event （GOE, 2.4-2.2 Ga）. The Yuanjiacun BIF consists mainly of subhedral-xenomorphic magnetite and quartz and rarely other minerals with a lower degree of metamorphism, from greenschist to lower amphibolite facies. The geochemical characteristics of this BIF are similar to those of Superior-type BIFs. Prominent positive La, Y, and Eu anomalies normalized by the Post Archean Australian Shale （PAAS） indicate that the primary chemical precipitate is a result of solutions that repre- sent mixtures of seawater and high-T hydrothermal fluids. The contamination from crustal detritus found is negligible based on low abundances of Al2O3 and TiO2 （〈0.5%） and of trace elements such as Th, Hf, Zr, and Sc （〈1.5 ppm）, as well as the lack of co-variations between Al2O3 and TiO2. In particular, the Yuanjiacun BIF samples do not display significant negative Ce anom- alies like those of the Archean iron formations, but rather, the Yuanjiacun BIF samples exhibit prominent positive Ce anoma- lies, low Y/Ho ratios, and high light to heavy REE （（Pr/Yb）sN） ratios, which are essentially consistent with the late Paleoprote- rozoic （〈2.0 Ga） BIFs around the world. These characteristics of the Yuanjiacun BIF samples imply that the ancient ocean （2.3-2.1 Ga） was redox-stratified from oxic shallow water to deeper anoxic water. The specific redox conditions of the ancient ocean may be related to the GOE, which gave rise to the oxidation of Ce and Mn in the upper water, and to the presence of a Mn

关键词： Yuanjiacun iron deposit geochemistry of BIFs Great Oxidation Event (GOE) Mn hydroxide shuttle precipitationmechanism

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Formation age and genesis of the banded iron formations from the Guyang Greenstone Belt,Western North China Craton

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Formation age and genesis of the banded iron formations from...

中国科学院地质与地球物理研究所2014年度（第14届）学术年会

作者： Li Liu Lianchang Zhang yanpei dai Key Laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of Sciences University of Chinese Academy of Sciences

Previous studies focused on banded iron formations(BIFs) from the eastern North China Craton(NCC),few were conducted on those of the western *** paper concentrates on two BIFs,Sanheming and Gongyiming,from the Guyang Greenstone Belt(GB),western *** U-Pb analyses of zircons from the amphibolite interlayers ofSanheming and Gongyiming BIFs gave upper intercept ages of 2562 ± 14 Maand 2569 ± 78 Ma,respectively,coupled with 2555 ± 56 Ma for the tonalite with BIF xenoliths,the formation age of the BIFs is inferred to be2.56-2.57 *** reconstruction based on geochemistry and field occurrence of the amphibolites shows that they are originally *** elements reveal that the basalts of Sanheming and Gongyiming are TMORB and N-MORB,*** from other locations of the Guyang GB in previous studies display island arc geochemical *** the lithologic assemblage of komatiite,basaltic komatiite,boninite,tholeiite,high-Mg andesite and Nb-enriched basalt identified by previous work,the geodynamic setting of the BIFs from Guyang GB is deduced to be a mantle plume erupting into the subduction zone and they were deposited in arc-related *** low contents of AlO,TiO and HFSE for the BIFs indicate negligible detritus ***-normalized REY profiles are characterized by LREE depletion and HREE enrichment,positive La,Gd,Y and Eu anomalies,weak negative Ce anomalies and Y/Ho weight ratios of 26-41,indicating a mixture of submarine high-temperature hydrothermal fluids and ***-normalized REE patterns for the BIFs are similar to those of the komatiites occurring at the bottom of the ***,it is speculated that submarine high-temperature hydrothermal fluids leached out the Fe and Si of oceanic volcanics during circulation,and they deposited due to the changed physiochemical conditions when the fluids mixed with the *** hydrothermally altered amphibolites proximal to the Gongyiming u

关键词： BIF Upgraded iron ores Guyang Greenstone Belt SIMS zircon U-Pb dating Source Hydrothermal fluids

Geochronological and geochemical constraints on the origin of clastic meta-sedimentary rocks associated with the Yuanjiacun BIF from the Lüliang Complex,North China

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Geochronological and geochemical constraints on the origin o...

中国科学院地质与地球物理研究所2015年度（第15届）学术年会

作者： Changle Wang Lianchang Zhang yanpei dai Caiyun Lan Key Laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of Sciences University of Chinese Academy of Sciences Guangzhou Institute of Geochemistry Chinese Academy of Sciences

The Lüliang Complex is situated in the central part of the western margin of the Trans-North China Orogen(TNCO)in the North China Craton(NCC),and consists of metamorphic volcanic and sedimentary rocks and granitoid *** Yuanjiacun Formation metasediments occupy roughly the lowest part of the Lüliang Group and are mainly represented by well-bedded meta-pelites(chlorite schists and sericite–chlorite phyllites),banded iron formations(BIFs)and meta-arenites(sericite schists),which have undergone greenschist-facies *** youngest group of detrital zircons from the meta-arenite samples constrains their maximum depositional age at350 *** combination with previous geochronological studies on meta-volcanic rocks in the overlying Jinzhouyu Formation,the depositional age of the Yuanjiacun Formation can be constrained between 2350 and 2215 *** metasediments have suffered varying degrees of source weathering,measured using widely employed weathering indices(e.g.,CIA,CIW,PIA and Th/U ratios).Source rocks of the low-Al metapelites have undergone severe chemical weathering,whereas those of the meta-arenites and high-Al metapelites have suffered relatively moderate chemical *** secondary K addition is recognized in the A–CN–K diagram for most of the studied *** geochemical features like the Al2O3/Ti O2values,trace element ratios(e.g.,Th/Sc)and REE patterns,suggest that the meta-arenites and high-Al metapelites are predominantly derived from felsic igneous sources,whereas the low-Al meta-pelites are sourced mainly from mafic *** with Nd isotopic data,it is proposed that the meta-arenites and high-Al meta-pelites were sedimentary erosion products of the less differential felsic terrain(likely the old upper continental crust).The low-Al meta-pelites,however,have geochemical affinities with both pelite-and BIFlike components,suggesting that they were mixtures of these two ***,the U–Pb ages of detrital z

关键词： Yuanjiacun Formation Lüliang Complex Trans-North China Orogen Detrital zircon Geochemistry Paleoproterozoic

Rare earth element and yttrium compositions of the Paleoproterozoic Yuanjiacun BIF in the Lliang area and their implications for the Great Oxidation Event(GOE)

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Rare earth element and yttrium compositions of the Paleoprot...

中国科学院地质与地球物理研究所2014年度（第14届）学术年会

作者： WANG ChangLe ZHANG LianChang LAN CaiYun dai yanpei Key Laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of Sciences University of Chinese Academy of Sciences Guangzhou Institute of Geochemistry Chinese Academy of Sciences

In China,most Precambrian banded iron formations(BIFs) are situated in the North China *** Yuanjiacun iron deposit,located in the Liiliang area,is arguably the most representative Superior-type *** iron deposit is coherent with the sedimentary rock succession of the Yuanjiacun Formation in the lower Liiliang Group,and was interpreted to be deposited at2.3-2.1 Ga,based on ages of overlying and underlying volcanic *** age overlaps with the time range of the Great Oxidation Event(GOE,2.4-2.2 Ga).The Yuanjiacun BIF consists mainly of subhedral-xenomorphic magnetite and quartz and rarely other minerals with a lower degree of metamorphism,from greenschist to lower amphibolite *** geochemical characteristics of this BIF are similar to those of Superior-type *** positive La,Y,and Eu anomalies normalized by the Post Archean Australian Shale(PAAS) indicate that the primary chemical precipitate is a result of solutions that represent mixtures of seawater and high-T hydrothermal *** contamination from crustal detritus found is negligible based on low abundances of A1O and TiO(<0.5%) and of trace elements such as Th,Hf,Zr,and Sc(<1.5 ppm),as well as the lack of co-variations between AlO and *** particular,the Yuanjiacun BIF samples do not display significant negative Ce anomalies like those of the Archean iron formations,but rather,the Yuanjiacun BIF samples exhibit prominent positive Ce anomalies,low Y/Ho ratios,and high light to heavy REE((Pr/Yb)) ratios,which are essentially consistent with the late Paleoproterozoic(<2.0 Ga) BIFs around the *** characteristics of the Yuanjiacun BIF samples imply that the ancient ocean(2.3-2.1 Ga) was redox-stratified from oxic shallow water to deeper anoxic *** specific redox conditions of the ancient ocean may be related to the GOE,which gave rise to the oxidation of Ce and Mn in the upper water,and to the presence of a Mn oxide shuttle in the ocean,resulting in varying REE patter

关键词： Yuanjiacun iron deposit geochemistry of BIFs Great Oxidation Event(GOE) Mn hydroxide shuttle precipitation mechanism

Source characteristics of the 2.5 Ga Wangjiazhuang Banded Iron Formation from the Wutai greenstone belt in the North China Craton:Evidence from neodymium isotopes

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Source characteristics of the 2.5 Ga Wangjiazhuang Banded Ir...

中国科学院地质与地球物理研究所2014年度（第14届）学术年会

作者： Changle Wang Lianchang Zhang yanpei dai Wenjun Li Key Laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of Sciences University of Chinese Academy of Sciences

Here we first present samarium(Sm)-neodymium(Nd) isotopic data for the .5 Ga Wangjiazhuang BIF and associated lithologies from the Wutai greenstone belt(WGB) in the North China *** geochemical data of the BIF indicate that there are three decoupled end members controlling REE compositions:high-T hydrothermal fluids,ambient seawater and terrigenous *** metasediment samples were collected for major and trace elements studies in an attempt to well constrain the nature of detrital components of the *** light rare earth elements patterns and mild negative Eu anomalies in the majority of these meta-sedimentary samples point toward felsic source ***,the relatively low Th/Sc ratios and positive ε(t) values are similar to those of the.5 Ga granitoids,TTG gneisses and felsic volcanics in the WGB,further indicating that they are derived from less differentiated *** Chemical Index of Weathering(CIW) values and features in the ACN-K diagrams for these meta-sediments imply a low degree of source ***-Nd isotopes of the chemically pure BIF samples are characterized by negative ε(t) values,whereas Al-rich BIF samples possess consistently positive ε(f) ***,the associated supracrustal rocks in the study area have positive ε(f) *** together,these isotopic data also point to three REE sources controlling the back-arc basin depositional environment of the BIF,the first being seafloor-vented hydrothermal fluids(ε(t) 0),the third being syndepositional detritus that received their features by weathering of a nearby depleted source(likely the arc)(ε(t) > 0).

关键词： Wutai greenstone belt(WGB) Neoarchean Wangjiazhuang BIF Neodymium isotopes North China Craton(NCC)

Petrology and geochemistry of the Wangjiazhuang banded iron formation and associated supracrustal rocks from the Wutai greenstone belt in the North China Craton:Implications for their origin and tectonic setting

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Petrology and geochemistry of the Wangjiazhuang banded iron ...

中国科学院地质与地球物理研究所2014年度（第14届）学术年会

作者： Changle Wang Lianchang Zhang Caiyun Lan yanpei dai Key Laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of Sciences University of Chinese Academy of Sciences Guangzhou Institute of Geochemistry Chinese Academy of Sciences

The Wutai greenstone belt(WGB) is one of the most extensively studied greenstone belts in *** with the Hengshan and Fuping complexes,these three associations compose the central segment of the Trans-North China Orogen(TNCO) in the North China Craton(NCC).The Wangjiazhuang banded iron formation(BIF) is located in the bottom of the Jingangku Formation of the *** associated supracrustal rocks consist of meta-basalts(amphibolites),meta-felsic volcanic rocks(leptynite)and metapelites(mica schist),which have experienced amphibolite-facies *** are commonly intercalated with the BIF,SIMS zircon U-Pb analyses on amphibolites suggest that the Wangjiazhuang BIF was formed at ca.2543±4 *** with most Neoarchean Algoma-type Bits in the NCC,these features indicate that a significant tectothermal event of the NCC have occurred *** assemblages of the Wangjiazhuang BIF are composed of quartz,magnetite,amphibole,and minor garnet,pyrite and *** precursor deposts of this BIF were likely feiric-oxyliydroxides,fine-grained carbonate oozes,silicate phases rich in Al-Ca-Mg-Fe and amorphous *** appearance of garnet and ferro-pargasite,high concentrations of AlO,HFSEs,Sc,and positive correlations among AIO,TiO,HFSEs and REE indicate that there was a significant terrigenous *** so,the Wangjiazhuang BIF samples display distinctively seawater-like REE+Y profiles,characterized by positive La and Y anomalies and HREE enrichment relative to LREE in PAAS-normalized REE *** positive Eu anomalies are also observed,which are typically from high-T hydrothermal *** addition,the true negative Ce anomalies recorded in the Wangjiazhuang BIF might indicate the onset of bottomwater oxidation at the Archean-Ptoterozoic boundary,at least in restricted *** have geochemical affinity with both MORB- and arc-like components,and the trace element characteristics of Icptynitcs are also consistent wi

关键词： Wutai greenstone belt Algoma-type BIF Tectonic setting of the BIF Neoarchean North China Craton(NCC)

Geochronology and geochemistry of the Nanfen iron deposit in the Anshan-Benxi area,North China Craton:Implications for 2.55 Ga crustal growth and the genesis of high-grade iron ores

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Geochronology and geochemistry of the Nanfen iron deposit in...

中国科学院地质与地球物理研究所2015年度（第15届）学术年会

作者： Mingtian Zhu yanpei dai Lianchang Zhang Changle Wang Li Liu Key Laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of Sciences University of Chinese Academy of Sciences

The Nanfen iron deposit,situated in the Anshan-Benxi area of the North China Craton(NCC),hosts scattered banded iron formations(BIFs) and BIF-hosted high-grade iron orebodies(defined by Fe OT> 80 wt.%).The associated roof and bottom rocks,which occur in parallel to orebodies,are mica quartz schist and chlorite hornblende schist(locally interlayers),*** PAAS-normalized rare earth element(REE) patterns indicate that quartz–magnetite banded iron formations(BIFs) are enriched in Heavy REEs with positive La,Eu and Y anomalies,indicating that the Nanfen BIF precipitated from a mixture of ambient seawater and submarine high-T hydrothermal fluids(.1%).In addition,the BIF exhibits low concentrations of AlO and Ti O with depletion in HFSEs(high field strength elements,e.g.,Nb,Ta,Zr,Hf and Ti),suggesting little contamination with continental *** lower Eu/Eu* values,the high-grade iron ores display similar geochemical features to the BIF,likely implying that they have a same iron source but did not form *** microprobe analyses(EMPA) and in situ LA-ICP-MS analyses reveal that in relative to the magnetite grains in high-grade ores,the magnetite grains in the BIF contain higher Mn O,Mg O and Zn concentrations,and lower AlO and REE abundances,implying different formation ***,we argue that high-grade ores are likely to be alteration products of primary *** hornblende schist(meta-basalt) samples exhibit low Si Ocontents(43.78–50.30 wt.%) with flat chondrite-normalized REE and N-MORB-normalized trace element patterns,which are similar to those of BABB(back-arc basin basalt).The zircon U–Pb dating results indicate that magmatic and metamorphic zircons from chlorite hornblende schist formed at approximately 2552 Ma and 2482 Ma,*** former volcanic age could constrain the deposition age of the Nanfen BIF,and the latter reflects a subsequent metamorphic event,which is also reflected by the 480 Ma hydrothermal

关键词： Banded iron formation High-grade iron ore Zircon U–Pb dating and Hf isotope Neoarchean crustal growth North China Craton

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BIF成因研究进展

地质科学 2014年第3期49卷 1018-1033页

作者：刘利张连昌代堰锫中国科学院地质与地球物理研究所、固体矿产资源研究室北京100029

BIF在全球广泛分布,BIF型铁矿是铁的重要来源。根据产出的构造背景将其分为阿尔戈玛型(Algoma-type)和苏必利尔湖型(Lake Superior-type)。BIF主要产出于前寒武纪的古老克拉通和/或年轻地体,形成时代集中在3.0~2.0 Ga,峰期为2.5 Ga左右... 详细信息

BIF在全球广泛分布,BIF型铁矿是铁的重要来源。根据产出的构造背景将其分为阿尔戈玛型(Algoma-type)和苏必利尔湖型(Lake Superior-type)。BIF主要产出于前寒武纪的古老克拉通和/或年轻地体,形成时代集中在3.0~2.0 Ga,峰期为2.5 Ga左右。前人对BIF型铁矿的成因研究着重于BIF的物质来源和Fe^(2+)氧化沉淀机制两个方面,但都尚未达成共识。物质来源的观点主要有大陆风化剥蚀、海底热液、海底热液和海水的混合物、热液淋滤洋壳、既有大陆物质来源又有热液来源;沉淀机制主要有生物沉淀和非生物沉淀两种认识,前者是指Fe^(2+)利用微生物(如蓝藻)光合作用产生的O_2氧化成Fe^(3+),或Fe^(2+)直接被微生物代谢氧化,后者主要包括热液与海水混合、密度流作用、相分离、紫外线引起Fe^(2+)氧化沉淀等。

关键词： BIF 物质来源沉淀机制