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Thermodynamic conditions of framework grain dissolution of clastic rocks and its application in Kela 2 gas field

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Science china Earth Sciences 2005年第1期48卷 21-31页

作者： LAI Xingyun, YU Bingsong, CHEN Junyuan, CHEN Xiaolin, LIU Jianqing, MEI Mingxiang, JING Weiguang & CHENG Suhua School of Earth Sciences and Mineral Resources, china University of Geosciences, Beijing 100083, china key laboratory of lithospheric tectonics, Deep-level Process and Exploration of ministry of education, Beijing 100083, china 1. china University of Geosciences School of Earth Sciences and Mineral Resources 100083 Beijing China 2. key laboratory of lithospheric tectonics Deep-level Process and Exploration of Ministry of Education 100083 Beijing China

Feldspar and clastic debris are the most important constituent framework grains of sedimentary clastic rocks and their chemical dissolution plays an essential role in the formation and evolution of the secondary pore in the reservoir rocks. On the basis of thermodynamic phase equilibrium, this study investigates the chemical equilibrium relationships between fluid and various plagioclase and K-feldspar in diagenesis of the sediments, particularly, the impact of temperature and fluid compositions (pH, activity of K+, Na+, Ca2+ and so on) on precipitation and dissolution equilibria of feldspars. Feldspar is extremely easily dissolved in the acid pore water with a low salinity when temperature decreases. The dissolution of anorthite end-member of plagioclase is related to the Ca content of the mineral and the fluid, higher Ca either in the mineral or in the fluid, easier dissolution of the feldspar. Moreover, the dissolution of albite end-member of plagioclase is related to Na of both the mineral and fluid, lower Na out of both the mineral and fluid, easier dissolution of the mineral. Similarly, lower-K fluid is more powerful to dissolve K-feldspar than the higher. The anorthite component of plagioclase is most easily dissolved in ground water-rock system, the albite is the secondary, and K-feldspar is the most stable. Selective dissolution of plagioclase occurs in diagenesis because of the plagioclase solid solution that is mainly composed of albite and anorthite end-members, Ca-rich part of which is preferentially dissolved by the pore water, in contrast to the Na-rich parts. Based on investigation of reservoir quality, secondary pore, dissolution structures of feldspar, clay minerals and ground water chemistry of the Kela 2 gas field of Kuqa Depression in the Tarim basin of Western china, we discovered that the secondary pore is very well developed in the highest quality section of the reservoir, and the plagioclase of which was obviously selectively dissolved, in c

关键词： dissolution of feldspar, thermodynamic conditions, groundwater pore chemistry, Kela 2 gas field.

Diagenetic and Catagenetic Transference of Noble Metal Elements in Lower Cambrian Black Rock Series, Southwest china

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Journal of Earth Science 2004年第1期 85-91页

作者： Li Shengrong key laboratory of lithospheric tectonics and Lithoprobing Technology, china University of Geosciences, ministry of education, Beijing 100083, china Gao Zhenmin Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, china Shen Junfeng key laboratory of lithospheric tectonics and Lithoprobing Technology, china University of Geosciences, ministry of education, Beijing 100083, china

Some extraditional types—black rock series types of platinum group element (PGE), gold and silver mineralization occurrences were found in the Lower Cambrian in Guizhou and Hunan provinces of southwest china where PGE concentration reaches more than 800×10 -6. Sea floor hydrothermal fluid eruption was suggested to have been the main origin of the ore-forming materials. The whole process from the sedimentation to the redistribution of the ore-forming elements occurred on the conditions of intermediate to weak alkaline, weak reduction to weak oxidation. The temperature for the sedimentation and redistribution of the ore-forming elements was lower than 210 ℃. At such a low temperature, inert elements such as PGE, Au and Ag could quite easily be remobilized.

关键词： transference of platinum group elements diagenetic and catagenetic periods black rock series china.

Discovery of double-peaking potassic volcanic rocks in Langshan Group of the Tanyaokou hydrothermal- sedimentary deposit, Inner Mongolia, and its indicating significance

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Science china Earth Sciences 2005年第6期48卷 822-833页

作者： PENG Runmin1, ZHAI Yusheng1, WANG Zhigang2 & HAN Xuefeng2 1. key laboratory of lithospheric tectonics and Lithoprobing Technology, ministry of education, china University of Geosciences, Beijing 100083, china 2. Inner Mongolia Geological Prospecting Institute, ministry of Chemical Industry, Hohhot 010074, china Correspondences should be addressed to Peng Runmin 1. key laboratory of lithospheric tectonics and Lithoprobing Technology Ministry of Education China University of Geosciences 100083 Beijing China 2. Inner Mongolia Geological Prospecting Institute Ministry of Chemical Industry 010074 Hohhot China

It is revealed that the protolith of gray-light brown potash-feldspar-leucogranulites and granulites in the 2nd formation of the LG in Tanyaokou deposit are quartz kerotophyre of synsedimentary eruption based on the following facts and features: (1) The rocks look compact and homogeneous without obvious crystals with naked eyes; (2) they contain blastoporphyritic or glomeroporphyritic and blasto-crystalloclastic crystals consisting of quartz with wavy extinction and albite with obvious alteration and deformation; (3) they also contain radiated and fibrous blasto-microspherulitic texture and swallow-tailed bifurcate and blasto-hollow-skeleton crystal texture, representing the rapid cooling characteristic of the magma during submarine volcanic eruption; (4) the major chemical compositions of the rocks are: SiO2 = 70.80%―76.00%, K2O (4.83%―6.22%)>Na2O(2.78%―3.80%), and K2O+Na2O = 8.63%―9.00%; and (5) their petro-chemical diagrams indicate that they are volcanic rocks. Together with the characteristic that they occur in the same sequence with potassic spilite (SiO2 = 46.12%―50.68%, K2O = 4.23%―5.93%>Na2O = 2.15%―3.14%, K2O+Na2O = 6.51%―8.08%), it can be confirmed that the vol-canics occurring in the 2nd Formation of the LG in Tanyaokou district are double-peaking potas-sic volcanic rocks. The discovery, together with the tuffs with ore minerals and the distribution of lead isotopic as well as the value of Co/Ni of pyrites >1 showing the obvious endogenic metali-zation, can prove that the Tanyaokou deposit is an untypical SEDEX-type deposit formed in the extension fault basin in the Mesoproterozonic aulacogen of the northern margin of the North china Platform, and its metallogenesis is related to the synsedimentary volcanic activities and the hydrothermal exhalation, and both the ore-forming material source and volcanics came from mantle or lower crust. These facts mentioned above, together with the meta-volcanic rocks (double-peaking) found in the Dongshengmiao and Huog

关键词： extensional rift basin, double-peaking potassic volcanic rocks, Mesoproterozoic, the 2nd formation of LG, Tanyaokou deposit, Inner Mongolia.

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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, china University of Geosciences, ministry of education of china, Beijing 100083, china 2. School of Earth Sciences and Mineral Resources, china University of Geosciences, Beijing 100083, china 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.

Supergene mobility of noble metal elements in black rock series

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Progress in Natural Science:Materials International 2002年第6期 51-55页

作者： LI Shengrong, XIAO Qiyun, SHEN Junfeng, SUN Li, YAN Baikun and LIU Bo(School of Geosciences and Land Resources, china University of Geosciences, Beijing 100083, china key laboratory of lithospheric tectonics Deep-level Process and Exploration, Minsitry of education, Beijing 100083, china) key laboratory of lithospheric tectonics Deep-level Process and Exploration Minsitry of Education Beijing 100083 China

In order to discuss the supergene mobility of noble metal elements in black rock series, measurements have been conducted with ICP-MS method for the contents of Ru, Rh, Pd, Ir, Pt, Au and Ag in the primary jordisite-rich black shale ore, in the supergene leached jordisite-rich black shale ore, in the pyrite-rich black shale ore and in the water of pit, well and stream of the mining area near Zhongnan Village, Zunyi District of Guizhou Province. The temperature, pH, electric conductivity, dissolved oxygen of the water were also measured. The pit water is acidic with high electrical conductivity and low dissolved oxygen. The total content of platinum group elements in the primary pyrite-rich black shale ore is only 1/13 of that in the primary jordisite-rich black shale ore. The Ag content in the former is only a half of that in the latter while the Au contents in the two kinds of ores are almost the same. Being leached under supergene condition, the contents of most of the noble metal elements except Au i

关键词： supergene water leaching process gold-silver-platinum group elements relative mobility physicochemical condition black rock series Guizhou.

Environmental Redox Changes of the Ancient Sea in the Yangtze Area during the Ordo-Silurian Transition

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Environmental Redox Changes of the Ancient Sea in the Yangtz...

Mesozoic basin evolution and tectonic mechanism in Yanshan, china

中国科学院地质与地球物理研究所2008学术年会

作者： YAN Detian~(1,2,*),CHEN Daizhao~1,WANG Qingchen~1,WANG Jianguo~1 and CHU Yang~1 1 State key laboratory of lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029 2 key laboratory of tectonics and Petroleum Resources,china University of Geosciences, ministry of education,Wuhan 430074

Extensive organic-matter(OM) rich facies(black shales) occur in the Ordo-Silurian boundary successions in the Yangtze area,South *** investigate the redox changes of the Yangtze Sea during the Ordo-Silurian transition,two OM sections(Wangjiawan in Yichang,Hubei Province,and Sanjiaguan in Zhangjiajie,Hunan Province) straddling the Ordo-Silurian boundary are *** measurements finished in this study include contents of the total organic carbon(TOC), pyrite sulphur,and different species of Fe,including dithionite-extractable Fe(Fe),pyrite Fe(Fe), HCl-extractable Fe(Fe),and total Fe(Fe),in black shales,as well as other redox proxies,such as the S/C ratio,the ratio between highly reactive Fe(Fe= Fe+ Fe) and Fe,and the Fe/(Fe + Fe) ratio, known as the degree of pyritization(DOP).In the Wangjiawan section,the Middle Ashgill sediments have high Fe/Fe ratios(0.20-0.77;avg.0.45),high DOP values(0.21-0.72;avg.0 54),and a relatively constant sulfur content independent of the organic carbor *** she contrast,the mid-early Hirnantian deposits generally have low Fe/Fe ratios(0.10-0.35;avg.0.21),low DOP values(0.11- 0.40;avg.0.28),and S/C values are clustering on the normal marine value(S/C = 0.36).The late Hirnantian and early Rhuddanian Jeposits,similar to those of the Middle Ashgill deposits,are characterized by high Fe/Ve ratios(0.32-0.49;avg.0.41),high DOP values(0.46-0.68;avg.0.53) and fairly constant sulfur mm *** data suggest the occurrences of marine anoxia on the Yangtze Sea shelf during intervals of the Mid Ashgill,Late Hirnantian and Early Rhuddanian,and ventilated and oxygenated marine conditions during the mid-early Hirnantian *** mid-early Hirnantian ventilated event was concomitant with the global glacial period,likely resulted from the glacio-eustatic sea-level fall and subsequent circulation of cold,dense oxygenated waters upon the shelf seabed. Accordingly,the abrupt change from oxygenated to anoxic marine waters from the late Hirnan

关键词： oceanic anoxia water column stratification Fe-S geochemistry organic carbon Late Ordovician Early Silurian Yangtze Sea South china

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Science china Earth Sciences 2004年第Z2期47卷 24-38页

作者： LIU Shaofeng1,2, LI Zhong3 & ZHANG Jinfang4 1. key laboratory of lithospheric tectonics, Deep-Level Process and Explovation, ministry of education of P. R. china, Beijing 100083, china 2. School of Geosciences and Resources, china University of Geosciences, Beijing 100083, china 3. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, china 4. Institute of Software, Chinese Academy of Science, Beijing 100080, china key laboratory of lithospheric tectonics Deep-Level Process and Explovation Ministry of Education of P.R.ChinaBeijing 100083 China School of Geosciences and Resources China University of Geosciences Beijing 100083 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Software Chinese Academy of Science Beijing 100080 China

The Mesozoic basins in Yanshan, china underwent several important tectonic transformations, including changes from a pre-Late Triassic marginal cratonic basin to a Late Triassic-Late Jurassic flexural basin and then to a late Late Jurassic-Early Cretaceous rift basin. In response to two violent intraplate deformation at Late Triassic and Late Jurassic, coarse fluvial depositional systems in Xingshikou and Tuchengzi Formations were deposited in front of thrust belts. Controlled by transform and extension faulting, fan deltas and lacustrine systems were deposited in Early Cretaceous basins. The composition of clastic debris in Late Triassic and Late Jurassic flexural basins respectively represents unroofing processes from Proterozoic to Archean and from early deposited, overlying pyroclastic rocks to basement rocks in provenance areas. Restored protobasins were gradually migrated toward nearly NEE to EW-trending from Early Jurassic to early Late Jurassic. The Early Cretaceous basins with a NNE-trending crossed over early-formed basins. The Early-Late Jurassic and Early Cretaceous basins were respectively controlled by different tectonic mechanisms.

关键词： Yanshan, Mesozoic, depositional provenance of basin, unroofing of provenance, basin evolution, tectonic mechanism.

Lithosphere types in North china:Evidence from geology and geophysics

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Science china Earth Sciences 2005年第11期48卷 1809-1827页

作者： QIU Ruizhao1,2, DENG Jinfu3, ZHOU Su3, LI Jinfa4, XIAO Qinghui1,5, WU Zongxu6 & LIU Cui3 1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, china 2. Development and Research Center, china Geological Survey, Beijing 100037, china 3. china University of Geosciences, Beijing 100083, china 4. china University of Geosciences, Wuhan 430074, china 5. Information Center of ministry of Land and Resources, Beijing 100812, china 6. Institute of Geology, State Seismological Bureau, Beijing 100029, china 1. Institute of Geology Chinese Academy of Geological Sciences 100037 Beijing China 2. Development and Research Center China Geological Survey 100037 Beijing China 3. china University of Geosciences 100083 Beijing China 4. china University of Geosciences 430074 Wuhan China 5. Information Center of ministry of Land and Resources 100812 Beijing China 6. Institute of Geology State Seismological Bureau 100029 Beijing China

On the basis of the characteristics of geology and geophysics in North china, three types of lithosphere, namely, the cratonic, the orogenic and the rift lithospheres can be classified. In terms of petrological method (based on the information from Precambrian rock assemblages, igneous activities, deep-seated enclaves, etc.) and the relationship between seismic velocity and rock compositions, the crust-mantle petrological and chemical structure models can be set up. Researching results indicate that the geology and geophysics of North china platform bears the similar characteristics in comparison with those of the global typical cratons. The Eerduosi(Ordos) block located in the west of the North china Platform is a remnant of cratonic lithosphere after the North china platform had undergone “activation” in Mesozoic and “reconstruction” in Cenozoic times. The continental crust consists mainly of TTG rock assemblage while the subcontinental lithosphere mantle mainly consists of strongly depleted harzburgite. The craton was finally formed in late Archaean and early Proterozoic, and has been kept in stability up to present; its crustal-mantle petrological structures of lithosphere can be set up as a reference for the study of North china craton and even Sino-Korean craton. In the Mesozoic period, the middle and east areas of North china platform were activated in the Yanshanian orogenic process, the continental crust was reformed by material and heat-transfer of convective mantle and the original crustal TTG component was reconstructed to be granitic crust, and the subcontinental lithosphere man- tle was replaced by the Yanshanian harzburgite-lherzolite. The Yanshan-Taihang Mountains were the remnants of orogenic lithosphere after the rifting in eastern North china in Cenozoic. The present thickness of continental crust and lithosphere in the Yanshan-Taihang Mountains is not equal to their thickness during the Yanshanian orogenic movement because they had undergone the

关键词： lithospheric types,evidence of geology and geophysics,crust-mantle petrological structure,deep process