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

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, {2. {3. of Geosciences, beijing 100083, {2. 2.state key laboratory of geological processes and mineral resources, beijing 100083, {2. School of Earth Science and mineral resources China University of Geosciences Beijing 100083 China state key {2. of {3. processes and mineral resources Beijing 100083 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 (δ1{2.) 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

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The equilibrium between diagenetic calcites and dolomites and its impact on reservoir quality in the sandstone reservoir of Kela 2.gas field

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Progress in Natural Science:Materials International 2007年第9期17卷 1051-1058页

作者： Gao Zhiqian1,Yu Bingsong2.3.and Lai Xingyun2.3.1.School of Energy {2.,china university of Geosciences,{3. 2.state key laboratory of geological processes and mineral resources,china university of Geosciences,{3. 3.Ministry of Education key {12. of Lithosphere Structure,Deep processes and Exploration Technique,china university of Geosciences,{3.) School of Energy resources China University of Geosciences Beijing 100083 China state key {2. of {3. processes and mineral resources China University of Geosciences Beijing 100083 China Ministry of Education key laboratory of Lithosphere Structure Deep Processes and Exploration Technique China University of Geosciences Beijing 100083 China

Based on the equilibrium theory of chemical reactions between water and rocks,this paper establishes a thermodynamic phase relationship diagram among calcites,dolomites and water solution under the condition of diagenesis based on the thermodynamic database of related minerals and fluids and dolomite's degree of order *** has been discovered that the equilibrium between calcites and dolomites in the diagenetic environment is strongly impacted by temperature and the Ca/Mg ratios in groundwater,and that the dolomite's degree of order in the diagenetic environment is a function of crystallization temperature and time,not controlled by water ***,the authors make a further analysis of the close relationship of chemical reaction between carbonate cements and pore water in the sandstone reservoirs of Kala 2.gas field in Kuche *** can be seen that there are different impacts on sandstone reservoir quality among the equilibrium system of calcites,dolomites and pore water at different depths of reservoirs.

关键词： diagenesis equilibrium between calcites and dolomites secondary pores Kela 2.gas field

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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. {2. key laboratory of {3. processes and mineral resources, china university of Geosciences, beijing {12., china 2. School of Earth Science and mineral resources, china university of Geosciences, beijing {12., china 3. Faculty of Earth Sciences, china university of Geosciences, Wuhan 43.074, china 1. state key {2. of {3. 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

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—1.2.). They display no Nb, Ta, Zr, Hf negativeanomalies, and show MORB features in 2.b-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 (0.512.55-0.512.78). Pb isotopes are in the rangeof ^(2.6)Pb/^(2.4)Pb (18.054-2..562., ^(2.7)Pb/^(2.4)Pb (15.53.-15.743. and ^(2.8)Pb/^(2.4)Pb(3..068-3..53.). 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.

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Mechanism for calcite dissolution and its contribution to development of reservoir porosity and permeability in the Kela 2.gas field,Tarim Basin,china

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Science china Earth Sciences 2008年第4期51卷 567-578页

作者： YU BingSong1,3. DONG HailLiang2.3.& RUAN Zhuang1,3.1 state key laboratory of {3. processes and mineral resources, china university of Geosciences, {12. 100083, china 2.Department of Geology, Miami university,Oxford, OH 45056, USA 3.Geomicrobiology laboratory, china university of Geosciences, {12., 100083, china state key {2. of {3. processes and mineral resources China University of Geosciences Beijing 100083 China Department of Geology Miami University Oxford OH 45056 USA Geomicrobiology laboratory China University of Geoscien

This study is undertaken to understand how calcite precipitation and dissolution contributes to depth-related changes in porosity and permeability of gas-bearing sandstone reservoirs in the Kela 2.gas field of the Tarim Basin, Northwestern china. Sandstone samples and pore water samples are col-lected from well KL2.1 in the Tarim Basin. Vertical profiles of porosity, permeability, pore water chem-istry, and the relative volume abundance of calcite/dolomite are constructed from 3.00 to 4000 m below the ground surface within major oil and gas reservoir rocks. Porosity and permeability values are in-versely correlated with the calcite abundance, indicating that calcite dissolution and precipitation may be controlling porosity and permeability of the reservoir rocks. Pore water chemistry exhibits a sys-tematic variation from the Na2.O4 type at the shallow depth (3.00-3.3. m), to the NaHCO3.type at the intermediate depth (3.3.―3.95 m),and to the CaCl2.type at the greater depth (3.2.―3.3. m). The geochemical factors that control the calcite solubility include pH, temperature, pressure, Ca2. concen-tration, the total inorganic carbon concentration (ΣCO2., and the type of pore water. Thermodynamic phase equilibrium and mass conservation laws are applied to calculate the calcite saturation {12. as a function of a few key parameters. The model calculation illustrates that the calcite solubility is strongly dependent on the chemical composition of pore water, mainly the concentration difference between the total dissolved inorganic carbon and dissolved calcium concentration (i.e., [ΣCO2. -[Ca2.]). In the Na2.O4 water at the shallow depth, this index is close to 0, pore water is near the calcite solubility. Calcite does not dissolve or precipitate in significant quantities. In the NaHCO3.water at the intermedi-ate depth, this index is greater than 0, and pore water is supersaturated with respect to calcite. Massive calcite precipitation was observed at this depth interval and

关键词： calcite dissolution porosity thermodynamic Tarim Basin

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SHRIMP U-Pb dating and Hf isotopic analyses of Middle Ordovician meta-cumulate gabbro in central Qiangtang, northern Tibetan Plateau

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Science china Earth Sciences 2010年第5期53卷 657-664页

作者： ZHAI QingGuo1 WANG Jun1, LI Cai2 & SU Li3.1 Institute of Geology, Chinese Academy of geological Sciences, beijing 10003., china 2 College of Earth Sciences, Jilin {3., Changchun 13.061, china 3.The geological laboratory Center and state key laboratory of geological processes and mineral {13., china {3. of Geo- sciences, beijing 100083, china 1. Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China2. College of Earth Sciences Jilin University Changchun 130061 China3. The Geological Laboratory Center and State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China

Metabasites consisting of metamorphic ultra-mafic rocks, cumulate gabbro, gabbro (diabase), basalt, and plagiogranite are exposed at the Taoxinghu area in central Qiangtang, northern Tibetan Plateau. Zircon SHRIMP U-Pb dating for the cumulate gabbro yields a weighted mean age of 467±4 Ma, which is the oldest and most reliable magmatic age in this area. Zircon 176Hf/177Hf ratios range from 0.2.2.15 to 0.2.2.57, with εHf(t) values of 5.02.0.2., indicating that the cumulate gabbro was mainly derived from the depleted mantle. In addition, geochemical data of metabasites suggest that they have similar characteristics to those in the mid-ocean ridge basalts (MORB). The Taoxinghu metabasites may represent the fragment of Early Paleozoic ophiolite in the "Central Uplift" of the Qiangtang, northern Tibetan Plateau.

关键词： Qiangtang cumulate gabbro SHRIMP dating Hf isotope

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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 {2. laboratory of {3. processes and mineral resources, china university of Geosciences, Wuhan 43.074, china 2. Graduate School of china university of Geosciences, Wuhan 43.074, china 3. Faculty of Earth Sciences, china university of Geosciences, Wuhan 43.074, china 1. state key {2. of {3. processes and mineral resources China University of Geosciences 430074 Wuhan China 2. Graduate School of china university of Geosciences 430074 Wuhan China 3. Faculty of Earth Sciences China University of Geosciences 430074 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 3.0 km.

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

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Science china Earth Sciences 2004年第10期47卷 896-911页

作者： ZHANG Changhou1,2. WU Ganguo1,2. WANG Genhou2. ZHANG Weijie2.& SONG Honglin2.1. key laboratory of Lithospheric Tectonics and Lithoprobing Technology, {2. {3. of Geosciences, Ministry of Education of {2., beijing 100083, {2. 2. School of Earth Sciences and mineral resources, {2. {3. of Geosciences, beijing 100083, {2. 1. key laboratory of Lithospheric Tectonics and Lithoprobing Technology China University of Geosciences Ministry of Education of China 100083 Beijing China 2. School of Earth Sciences and mineral resources China University of Geosciences 100083 Beijing China

The northwest trending tectonic belt in the middle part of the Mesozoic intraplate Yanshan Orogenic Belt, northeast Hebei Province, is composed of thrusts, extensional faults, strike-slip faults and syntectonic sedimentations as well. The northeastward basement-involved major thrusting deformation occurred between 174Ma and 168MaBP and was followed by an intrusion of the granitic plutonic rocks. As a part of the post-thrusting extensional deformations a northwest extending volcano-sedimentation system of Late Jurassic and Early Cretaceous formed in the southwest side of the belt. These volcano-sedimentary sequences are divided into Tuchengzi Formation, Zhangjiakou Formation, Yixian Formation and Jiufotang Formation re- spectively. They are characterized by southeastward migration as a result of the increasing down-dip slip displacement along the major extensional fault toward the southeast of the belt. The provenance area of the Jiufotang Formation north to it experienced southwestward thrusting during and after its later sedimentation. The thrusting in this stage resulted in the formation of an asymmetric footwall syncline with vergence to SW in the Jiufotang Formation in the NE side of the basin. Finally a dextral strike-slip deformation occurred along the NW tectonic belt. The striking tectono-geomorphological features and present seismic activities along this belt indicate that it has been being active since Cenozoic era and is still in the active state at present. This northwest extending tectonic belt was following the same direction and location as the existing fault systems within the basement as revealed by former geological and geophysical studies. So it is reasonable to infer the Mesozoic deformation along this belt to be a result of reactivation of the basement structures in a favorable tectonic stress field. The reactivation of basement struc- tures might be taken as one of the mechanisms of intraplate deformation and orogeny.

关键词： Yanshan Orogenic Belt, northwest extending tectonic complex, thrust system, geochronology.

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Zircon and apatite fission track analyses on mineralization ages and tectonic activities of Tuwu-Yandong porphyry copper deposit in northern Xinjiang, china

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Science china Earth Sciences 2007年第12期50卷 1787-1795页

作者： YUAN WanMing1,BAO ZengKuan2.DONG JinQuan2.GUO ZhaoJie3.& DENG Jun1 1 state {2. laboratory of {3. processes and mineral resources,china university of Geosciences,beijing100083.china 2.laboratory of Nuclear Analysis Techniques,Institute of High Energy Physics,Chinese Academy of Sciences,beijing 10003.,china 3.Department of Geology,Peking university,beijing 100871,china 1. state key {2. of {3. processes and mineral resources China University of Geosciences Beijing 100083 China 2. laboratory of Nuclear Analysis Techniques Institute of High Energy Physics Chinese Academy of Sciences Beijing 100039 China 3. Department of Geology Peking University Beijing 100871 China

The mineralization ages reported in the past in the Tuwu-Yandong copper district not only are different,but also fall into the Hercynian *** study has achieved 9 zircon and 7 apatite fission track analysis *** zircon fission track ages range from 158 Ma to 2.9 Ma and the apatite ages are between 64 Ma and 140 *** mineralization accords with the regional tectonics in the copper *** consider that the zircon fission track age could reveal the mineralization age based on annealing zone temperature of 140―3.0℃ and retention temperature of ～2.0℃ for zircon fission track,and metallogenetic temperature of 12.―3.0℃ in this ore *** three mineralization epochs have been identified,i.e.,2.9―2.6 Ma,2.3}―2.0 Ma and 165―158 Ma,and indicate occurrence of the min-eralization in the Indosinian and Yanshan *** to apatite fission track ages,the three tectonic-mineralizing epochs are 140―13. Ma,109―97 Ma and 64 Ma,which means age at about 100℃ after the *** three epochs lasted 146 Ma,108 Ma and about 100 Ma from ～2.0℃ to ～100℃ and trend decrease from early to *** is shown by the fission track modeling that this district underwent three stages of geological thermal histories,stable in Cretaceous and cooling both before Cretaceous and after 2. Ma.

关键词： mineralization age, tectonic epoch, fission track, zircon, apatite, Tuwu-Yandong, Xinjiang

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Experimental study on interaction between simulated sandstone and acidic fluid

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Petroleum Science 2009年第1期6卷 8-16页

作者： Zhang Yongwang Zeng Jianhui Yu Bingsong state key {2. of Petroleum Resource and Prospecting China University of Petroleum Beijing 102249 China Basin and Reservoir Research Center China University of Petroleum Beijing 102249 China state key {2. of {3. processes and mineral resources China University of Geosciences Beijing 100083 China

In order to investigate the controlling mechanism of temperature, fluid and other factors on water-rock interaction in the diagenetic process, we performed a series of simulated experiments on the interaction between two kinds of fluids with different salinity and a composite mineral system （simulated sandstone）, which contains albite, K-feldspar and other minerals. The experimental results showed that acidity was the most important factor that affected the dissolution of minerals in the composite mineral system. The lower the pH value, the more easily the minerals dissolved. At the same pH value, the dissolution abilities of different acids for various mineral components were also different. Compared to hydrochloric acid （inorganic acid）, oxalic acid （organic acid） was more able to dissolve aluminosilicate minerals. However, the dissolution ability of oxalic acid for carbonate minerals was lower than that of hydrochloric acid. In the process of fluid-rock interaction, dissolution of feldspar was relatively complicated. Increase of temperature would accelerate the dissolution of feldspar. Under acidic conditions, albite had a higher dissolution rate than K-feldspar. K-feldspar could dissolve and convert into montmorillonite and kaolinite, while albite could dissolve and convert into kaolinite both at 40℃ and 80℃. Presence of organic acid, and decrease of pH value and water salinity were all favorable for the dissolution of feldspar, but weakened the ability to form clay minerals.

关键词： Fluid simulated sandstone dissolution static experiment

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Late Mesozoic metamorphic core complexes: new constraints on lithosphere thinning in North china

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Progress in Natural Science:Materials International 2006年第6期16卷 633-638页

作者： LIU Junlai, GUAN Huimei, JI Mo and HU Ling (state key {2. of {3. processes and mineral resources, china university of Geosciences, and key {2. of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education, china university of Geosciences, {13. 100083, china) [a] state key {2. of {3. processes and mineral resources China University of Geosciences Key Laboratory of Lithosphere Tectonics Beijing China [b] Lithoprobing Technology of Ministry of Education China university of Geosciences Beijing China

Metamorphic core complexes (mcc’s) are among the most prominent structural styles of lithosphere extension and thinning during late Mesozoic in North china. In this paper, the geometrical, kinematic and age characteristics of some of the mcc’s, e.g. Liaonan, Waziyu (Yiwulushan), Yunmengshan, etc., are discussed. Some common characteristics, such as kinematic polarity, geometric asymmetry, occurrence over a time span, scattered and isolated distribution, and progressive development, can provide direct constraints on the regional lithosphere extension and thinning in North china, which does not favor the prevailing plume model, a general de-lamination model or extensional collapse of overthickened orogenic crust. We argue that several aspects, such as the kinematic polarity at depths during lithosphere extension, gradual break-up of lithosphere plate, relationship between magmatism and regional extension, and coeval activity of mcc’s and Tan Lu fault, should be taken into consideration when constructing a more reasonable model for lithosphere extension and thinning in North china.

关键词： North china late Mesozoic metamorphic core complex lithosphere extension and thinning.

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