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Multistage evolution of continental collision orogen:A case study for western Dabie orogen

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Chinese Science Bulletin 2009年第15期54卷 2568-2579页

作者： WU YuanBao state key laboratory of geological processes and mineral resources, faculty of earth sciences, china university of geosciences, wuhan 430074, china state key laboratory of Continental Dynamics, Department of Geology, Northwest university, Xi’an 710069, china state key laboratory of geological processes and mineral resources Faculty of Earth Sciences China University of Geosciences Wuhan China state key laboratory of Continental Dynamics Department of Geology Northwest University Xi’an China

The foramtion and evolution of collisional orogen is a prominent feature along convergent plate margins, and is generally a complex process. This article presents an integrated study of zircon genesis, U-Pb age and Lu-Hf isotope composition as well as geological characteristics for the western Dabie orogen to constrain its multi-stage evolution history. The results suggest that the formation of oceanic crust in the Huwan area was constrained at ca. 400―430 Ma, which was slightly later than the collision of the northern Qinling with the North china Block. It formed in a marginal basin in the northern margin of the Yangtze Block. The peak metamorphism of eclogite in the Huwan area occurred at ca. 310 Ma, and the timing of the initial exhumation of oceanic eclogite was about 270 Ma. The high to ultrahigh pressure (HP-UHP) metamorphic rocks in the Xinxian and the Hong'an metamorphic zones have the same ages and natures as those of the HP-UHP metamorphic rocks in the other Dabie-Sulu terrains, and also have experienced multi-stage exhumation, and thus can be taken as a coherent part of the Dabie-Sulu orogen. Therefore, the Qinling-Dabie-Sulu orogen is a typical multi-stage continental collision orogen, with an amalgamation process extending more than 200 Ma.

关键词：大别造山带大陆碰撞西部演变超高压变质岩碰撞造山带苏鲁造山带变质岩区

Exsolution of ilmenite and Cr-Ti magnetite from olivine of garnet-wehrlite

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Science china earth sciences 2005年第9期48卷 1368-1376页

作者： LIU Xiangwen1,2, JIN Zhenmin1,3, QU Jing2 & WANG Lu2 1. state key laboratory of geological processes and mineral resources, china university of geosciences, wuhan 430074, china 2. Graduate School of china university of geosciences, wuhan 430074, china 3. faculty of earth sciences, china university of geosciences, wuhan 430074, china state key laboratory of geological processes and mineral resources China University of Geosciences Wuhan China Graduate School of china university of geosciences Wuhan China faculty of earth sciences China University of Geosciences Wuhan China

Exsolution of rod-like ilmenite (Ilm) and Cr-Ti magnetite (Mt) have been found in olivine of garnet-wehrlite from the core of Chinese Continental sciences Drilling (CCSD). Their composition, morphology, crystal structure and their topotaxies with host olivine have been studied in detail by the transmission electron microscopy (TEM) and electron probe microanaly- sis (EPMA) technique. It shows that rod-like Ilm exsolution reported in this paper has similar characteristic with that of Alpe Arami olivine, while Cr-Ti magnetite exsolution mentioned in this paper has large discrepancy with chromite exsolution in Alpe Arami olivine. These observations suggest that both of the exsolutions found in this paper should be solid solution phases in β-olivine at their first period, then experiencing decomposition of solid solution and therefore forming Ilm and Cr-Ti magnetite exsolution with the pressure decreasing. So, this garnet-wehrlite perhaps had been ever located in mantle transition zone with a minimum depth of 300 km.

关键词： garnet-wehrlite, ilmenite, magnetite, exsolution, CCSD.

Exploring the deep biosphere

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Science china earth sciences 2011年第2期54卷 157-165页

作者： FANG JiaSong1,2 & ZHANG Li3 1 state key laboratory of Marine Geology, Tongji university, Shanghai 200092, china 2 College of Natural and Computational sciences, Hawaii Pacific university, Kaneohe, HI 96744, USA 3 state key laboratory of geological processes and mineral resources, faculty of earth sciences, china university of geosciences, wuhan 430074, china state key laboratory of Marine Geology Tongji University Shanghai China College of Natural and Computational sciences Hawaii Pacific University Kaneohe USA state key laboratory of geological processes and mineral resources Faculty of Earth Sciences China University of Geosciences Wuhan China

Over the past two decades, scientific drilling into sediments and rocks in the ocean and the continent has revealed the presence of physiologically and phylogenetically complex microbial life in the deep subsurface. Microorganisms, most of which have no cultured or known relatives in the surface biosphere, have been discovered in sediments and rock at depth as deep as 1 km below the seafloor and more than 3 km deep in the continent. The deep biosphere probably represents the most voluminous part of the global biosphere and may constitute as much as 50% of the earth’s biomass. In this article, we review the current knowledge of and most recent advances in studying the deep biosphere and suggest directions in future research.

关键词： deep biosphere Thomas Gold microorganism biomass DNA ribosome ODP CARD-FISH dark energy lipids serpentinization

Indian Ocean-MORB-type isotopic signature of Yushigou ophiolite in North Qilian Mountains and its implications

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Science china earth sciences 2006年第6期49卷 561-572页

作者： HOU Qingye1,2, ZHAO Zhidan1,2, ZHANG Hongfei3, ZHANG Benren3 & CHEN Yuelong2 1. state key laboratory of geological processes and mineral resources, china university of geosciences, Beijing 100083, china 2. School of earth Science and mineral resources, china university of geosciences, Beijing 100083, china 3. faculty of earth sciences, china university of geosciences, wuhan 430074, china state key laboratory of geological processes and mineral resources China University of Geosciences Beijing China School of earth Science and mineral resources China University of Geosciences Beijing China faculty of earth sciences China University of Geosciences Wuhan China

In order to explore the disputed issue concerning the tectonic affinity ofthe ancient ocean mantle of North Qilian Mountains (NQM), geochemical and Sr, Nd, Pb isotopiccompositions of pillow basalts of the Yushigou Ophiolite (YSGO) suite from NQM have been analyzedsystematically. The pillow basalts exhibit tholeiitic characteristics, with flatchondrite-normalized REE patterns ((La/Yb)_N = 0.98—1.27). They display no Nb, Ta, Zr, Hf negativeanomalies, and show MORB features in 2Nb-Zr/4-Y and Ti/100-Zr-YX3 tectonic discrimination *** results indicate that the Yushigou ophiolite is most likely to be formed in a mid-ocean ridgeor mature back-arc basin. Their isotopic data show a relatively broad and enriched ^(87)Sr/^(86)Sr(0.70509 — 0.70700), restricted ^(143)Nd/^(144)Nd (0.512955-0.512978). Pb isotopes are in the rangeof ^(206)Pb/^(204)Pb (18.054-20.562), ^(207)Pb/^(204)Pb (15.537-15.743) and ^(208)Pb/^(204)Pb(38.068-38.530). These isotopic data imply that the basalts originated from the depleted mantle(DMM), with the involvement of enriched mantle components (mainly EMII). Geochemical comparisonsbetween the basalts in YSGO and the MORB-type basalts of ophiolite suites occurring in the knownancient Tethyan tectonic domain indicate that the ancient oceanic mantle represented by YSGO suiteforming in early Paleozoic in the North Qilian Moutains is very similar to the Tethyan mantle inboth trace elements and isotopic compositions. The North Qilian Mountains should be a part of theTethyan tectonic domain in early Paleozoic. This further implies that the Tethyan tectonic domaincan be deduced to early Paleozoic in the study area, which will be helpful to discussing thetectonic affinity and evolution of the North Qilian Mountains.

关键词： geochemistry, Indian Ocean-MORB-type isotopic signatures, Tethyan tectonic domain, Yushigou ophiolite, North Qilian Mountains.

Petrogenesis of Indosinian volcanic rocks in Songpan-Garze fold belt of the northeastern Tibetan Plateau:New evidence for lithospheric delamination

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Science china earth sciences 2010年第9期53卷 1316-1328页

作者： CAI HongMing1,2, ZHANG HongFei1,2, XU WangChun1,2, SHI ZhangLiang1,2 & YUAN HongLin3 1 state key laboratory of geological processes and mineral resources, wuhan 430074, china 2 faculty of earth sciences, china university of geosciences, wuhan 430074, china 3 state key laboratory of Continental Dynamics, Northwest university, Xi’an 710069, china state key laboratory of geological processes and mineral resources Wuhan China faculty of earth sciences China University of Geosciences Wuhan China state key laboratory of Continental Dynamics Northwest University Xi’an China

In the Songpan-Garze fold belt of the northeastern Tibetan Plateau, an Indosinian lithospheric delamination model has been proposed, based on previous investigation of widespread granitoids. However, this model lacks comparable information from volcanism in the area. During the Indosinian delamination in the Songpan-Garze fold belt, whether partial melting of litho- spheric mantle taken place is debated. This paper reports U-Pb zircon LA-ICP-MS ages, geochemical and Sr-Nd-Hf isotopic compositions from the Aba and Wasai calc-alkaline volcanic rocks in the central Songpan-Garze fold belt. Obtained magma crystallization ages are 210±3 Ma for the Aba andesite and 205±1 Ma for the Wasai andesite. These are consistent with magma crystallization ages of the late Indosinian granitoids in the Songpan-Garze fold belt that formed in a post-collisional tectonic setting. The Aba and Wasai andesites have distinct geochemical singnatures. The former has higher Al2O3, K2O, Rb but lower Na2O, Ba and Sr contents, suggesting differences in their magmatic evolution. The Aba andesites have ISr values of 0.7070-0.7076 and εNd(t) values of -3.9 to -5.3, and the Wasai andesites have ISr values of 0.7075-0.7077 and εNd(t) values of -3.6 to -3.9. Zircons show εHf(t) values of -3.7 to 0.3 for the Aba andesites and -2.7 to 5.5 for the Wasai andesites. Geochemical and Sr-Nd-Hf isotopic compositions indicate that fractional crystallization and crustal assimilation processes are not key roles for their magma evolution, implying that their chemical compositions are those of primary melts. We suggest that the magma of the Aba andesites originated predominantly from a crustal source, with a minor mantle-derived component. The source region of the magma was likely at the crust-mantle boundary. The magma of the Wasai andesites resulted from partial melting of lithospheric mantle, which was probably metasomatized by fluids so that it was amphibole bearing. The petrogenesis of the Aba and Wasai andesite

关键词： volcanism U-Pb dating geochemistry petrogenesis lithospheric delamination Songpan-Garze fold belt

Experimental remolding on the caprock's 3D strain field of the Indosinian-Yanshanian epoch in Tongling deposit concentrating area

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Science china earth sciences 2005年第7期48卷 863-874页

作者： DENG Jun1,HUANG Dinghua2,WANG Qingfei1,WAN Li1,SUN Zhongshi3,YANG Liqiang1 & GAO Bangfei1 1. state key laboratory of geological processes and mineral resources,china university of geosciences,Beijing 100083,china 2. faculty of earth sciences,china university of geosciences,wuhan 430074,china 3. Department of earth sciences,Jilin university,Changchun 130061,china state key laboratory of geological processes and mineral resources China University of Geosciences Beijing 100083 China faculty of earth sciences China University of Geosciences Wuhan 430074 China Department of earth sciences Jilin University Changchun 130061 China

Based on field observations and rheology analysis, we perform one analogue experiment and remold the 3D structural frame of Tongling deposit concentrating area firstly. Then we disassemble and dialyze the 3D structures of the model using the methods of "slicing" and "stripping". A series of sliced planes vertical to the fold hinges show similar landscapes of that in the drill hole profiles. Meanwhile, layer stripping analysis indicates that the deformation features of each layer in the model are qualitatively analogical to those obtained from field observations. Through contrasting the 3D structure between the experimental model and the field phenomena, we verify the following 3D deformation features of the caprock in this area: (1) the Tongling area mainly consists of three series of NE S-typed fold groups; (2) in the uniform stress field, the incoherent folds universally develop in different positions, along different axes as well as in different strata; (3) the faults propagate upward which are mostly inter-bedded detachment faults, while the fold amplitudes decrease while going deeper; and (4) the folds and cleavages are highly developed in the Silurian System indicating that the deformation effect of the Indosin-ian-Yanshanian structural layer terminates at this layer, which suggests that the Silurian System is the crucial layer for the inversion between brittle and plastic deformation domains and the underlying strata are subject to the control of another deformation system with distinct properties.

关键词： Tongling deposit concentrating area Indosinian-Yanshanian epoch 3D structural frame of the caprock analogue experiment slicing and stripping analysis structural model.

Analytical method of Cr stable isotope and its application to water pollution survey

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Chinese Science Bulletin 2010年第7期55卷 664-669页

作者： GAO YongJuan 1,2,3,MA Teng 4,5,LING WenLi 1,2,LIU CunFu 4,5 & LI Li 4,5 1faculty of earth Science,china university of geosciences,wuhan 430074,china 2state key laboratory of geological processes and mineral resources,china university of geosciences,wuhan 430074,china 3 Graduate School,china university of geosciences,wuhan 430074,china 4 Biogeological and Environmental Geology laboratory of Ministry of Education(china university of geosciences) ,wuhan 430074,china 5 Sino-Hungary Joint laboratory of Environmental sciences and Health,china university of geosciences,wuhan 430074,china faculty of earth Science China University of Geosciences Wuhan China state key laboratory of geological processes and mineral resources China University of Geosciences Wuhan China Graduate School China University of Geosciences Wuhan China Biogeological and Environmental Geology laboratory of Ministry of Education (china university of geosciences) Wuhan China Sino-Hungary Joint laboratory of Environmental sciences and Health China University of Geosciences Wuhan China

High Cr(VI) concentration is a potential serious risk to environment and ecologic ***,it is essential to effectively monitor Cr contamination in water systems and scientifically evaluate its evolution trend.A new method of in-situ tracer technique by Cr isotopic analysis for quantitatively estimating Cr-contamination and its regional evolution in natural waters as well as a case application are reported in this *** on documented literatures,an experimental procedure for chemical separation and purification of Cr in water samples and its analytical method for Cr isotopic measurement by thermal ionization mass spectrometry(TIMS) are *** samples collected around a chemical factory in Hubei Province were analyzed by this *** samples showδ53Cr values ranging from-1.7‰to 7.3‰and an elevating trend with an increasing in distance from the sampling site to pollution source.A functional correlation following Rayleigh fractionation law was established between sample'sδ53Cr value and its extent of Cr *** study suggests that Cr isotopic analysis is an effective method to reveal the spatial distribution and its evolution trend of Cr contamination in the regional water *** is thus helpful to assessing the self-purifying ability of local water system according to Cr isotopic fractionation.

关键词：铬(VI) 水污染调查稳定同位素应用同位素分析供水系统演变趋势示踪技术

Carbon isotope composition of the Lower Triassic marine carbonates, Lower Yangtze Region, South china

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Science china earth sciences 2006年第3期49卷 225-241页

作者： ZUO Jingxun1,2, TONG Jinnan3, QIU Haiou4 & ZHAO Laishi3 1. Nanjing Institute of Geology and Palaeontology, Chinese Academy of sciences, Nanjing 210008, china 2. Henan Institute of geological Survey, Zhengzhou 450007, china 3. state key laboratory of geological processes and mineral resources at china university of geosciences, wuhan 430074, china 4. faculty of Material sciences and Chemical Engineering, china university of geosciences, wuhan 430074, china Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing China Henan Institute of geological Survey Zhengzhou China state key laboratory of geological processes and mineral resources at china university of geosciences Wuhan China faculty of Material sciences and Chemical Engineering China University of Geosciences Wuhan China

Studies on three Lower Triassic sections located on the shallow water platform, the deep water slope and in the deep water basin in the Lower Yangtze Region, South china, show the similar trend of carbon isotope evolution. Biostratigraphic correlations among the Lower Triassic sections on the basis of standard conodont zones indicate that three negative shifts occurred in the Griesbachian, the Smithian and the late Spathian stages respectively, and one distinctly positive shift occurred in the early Spathian stage. Trend of carbon isotope evolution of the Lower Triassic reflects some significant changes in the global carbon cycle. Moreover, δ 13C background values are intensively controlled by palaeogeographic environment. In general, δ 13C values from deep-water slope carbonates are lighter than those from carbonate platform and heavier than those from deep-water basin carbonates. The positive carbon isotope excursion may be induced by a significant amount of organic carbon burial in marine sediments and increase in primary productivity. The large negative carbon isotope excursions during the Early Triassic in Lower Yangtze Region are interpreted to relate to volcano eruptions based on tuffaceous claystone interlayers observed near the Permian-Triassic boundary, the Induan- Olenekian boundary and the Lower Triassic-Middle Triassic boundary.

关键词： Lower Triassic, carbon isotope compositions, palaeogeography, volcanic eruptions, Lower Yangtze Region.

Spatio-temporal carbon isotope variation during the Ediacaran period in South china and its impact on bio-evolution

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Science china earth sciences 2009年第10期52卷 1520-1528页

作者： WANG XinQiang1 & SHI XiaoYing1,2 1 School of earth Science and mineral resources, china university of geosciences, Beijing 100083, china 2 state key laboratory of geological processes and mineral resources, Beijing 100083, china School of earth Science and mineral resources China University of Geosciences Beijing China state key laboratory of geological processes and mineral resources Beijing China

The Ediacaran period is characterized by the extremely negative carbon isotope anomalies and great biotic evolution in earth history. At least four negative carbon isotope anomalies have been reported from this interval in South china so far. It is traditionally argued that the isotope variations can be used as a useful tool for global correlation of Ediacaran succession; however, more and more researches argued against this idea. We reviewed the previously published carbon isotope data in South china, and distributed the mean values of a certain time to the paleogeographic maps. The results show that the carbon isotope values (δ13C) vary greatly in different environments, but a clear tendency of becoming lighter from shallow platform to deep basin, with a maximum variation up to 1‰ Moreover, the important changes in Ediacaran biota, marked by the introducing of new taxa or ecologic groups, seemed to always postdate the negative anomalies but coincide with the positive shift. If the negative excursions represented the oxidation of a large dissolved organic carbon (DOC) reservoir in the ocean, the diverse Ediacaran organisms and the carbon isotope anomalies may suggest totally different environments: oxic and anoxic/euxinic. We also suggest that the elimination of euxinic state through precipitation of pyrites is one of the important environment factors in prompting the Ediacaran bio-evolution.

关键词： Ediacaran South china carbon isotope spatio-temporal variations bio-evolution