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Deep Geodynamics of Yanshain Movement WU Fu-yuan, SUN De-you, ZHANG Guang-liang, REN Xiang-wen J4    Abstract （2080）      PDF （2278KB）（2020）       Knowledge map    Save The eastern China was characterized by intensive magmatic ac tivities, structrual deformation, basin formation and mineralization in the Mesozoic, whic h wa s described as the Yanshain Movement Wong (1927). Although a lot of studies have been conducted in the past 70 years on the Yanshain Movem ent, a warmly debate still exists about its geodynamic background, such as the sub duction and back-arc extension of Pacific plate, continental -continental collisi on, sheared strike-slip continental margin, impacting and lithosph eric thinning , etc. A comprehensive study about the mineralogical, petrological and Sr-Nd isotopic features of Cenozoic basalts and their mantle xenoliths has indicated t hat the eastern China in Yanshain Period was characterized by lithospheric delaminat ion, especially the direct contact of asthenospheric mantle with the crust. Most of the pre-existed ancient lithospheric mantle had been delaminat ed, the present lithospheric mantle was formed since the Late Mesozoic. According to the presen t st udy, this lithospheric removal is probably related to the subduction of Pacific Oceanic Plate. The early stage (170 Ma or so) of subduction of eastern oceanic p lat e thickened the lithosphere in the eastern China, which resulted in the mantle d elamination in 160 and 145～120 Ma duo to the gravity instability of thicken ed lithosphere. Therefore, the nature of Yanshain movement is the thinning, even disappearing of lithospheric mantle beneath eastern China. This phenomenon is r are in the world and was reported only in the Basin and Range of western United States. Du ring the period of lithospheric removal, the asthenosphere upwelling and heating , and the underplating of mantle-derived magma in the lower cr ust resulted in th e intensive Late Mesozoic magmatism-tectonism-minera lization of Yanshain Movement in China. This research also suggests that the present lithospheric mantle beneath e astern China is juvenile, and does not correspond to the old ages found in the o verlyi ng crustal rocks. This implies a mantle-crust decoupling, which is inconsistent with the results of present researches on the major Archean Cratons in the world. Th erefore, further investigation should be conducted to study the mechanism of th is process. Related Articles | Metrics Cited: Baidu(338)

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My Thinking about Granite Geneses of South China ZHOU Xin-min J4    Abstract （1746）      PDF （2896KB）（2572）       Knowledge map    Save The characteristics，genetic models and tectonic frameworks of the granites for four geological periods in South China are described and discussed in this paper．Several geological problems of South China which are worth further thinking over are raised by the present author Related Articles | Metrics Cited: Baidu(315)

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Metallogeneses and Their Geodynamic Settings Related to Mesozoic Granitoids in the Nanling Range Hua Ren-min, Chen Pei-rong, Zhang Wen-lan, Yao Jun-ming, Lin Jin-fu, Zhang Zhan-shi, Gu Sheng-yan J4    Abstract （1956）      PDF （4870KB）（1180）       Knowledge map    Save Affected by the compressive stress from the Indo-China Peninsula, the Indosinian Orogenesis, characterized by collision, thrust and uplifting, took place inside the South China plate the Indosinian granitoids in the Nanling Range and vicinity areas are mostly of during 250 -230 Ma. The ages of 240 -205 Ma, indicating that they were emplaced in both syn-collision and post-collision geodynamic settings. No important granite-related metallogeneses occurred in this duration. A post-orogeny setting started from the beginning of the Yanshanian Period, which controlled the large-scale granitic magmatism and related metallogeneses. This paper makes the first attempt to divide the Yanshanian Period into three sub-periods, i.e. the Early, Middle and Late Yanshanian Periods, based on the metallogenic features of granitoids and their geodynamic backgrounds. The magmatic association of the Early Yanshanian Period （about 185 - 170 Ma）comprises four categories of magmafism, i. e. basalt, bimodal volcanics, A-type granite, and the intra-plate high-K calc-alkaline, which indicates the beginning of extensionthinning of lithosphere and upwelling of mantle material in a relative small and local extent. Pb-Zn, Cu, and Au mineralization associated with high-K calc-alkaline magmatism represents the metallogeny of this period. During the Middle Yanshanian Period, lithospheric extending-thinning developed more widely and intensively, and hence the mantle upwelling and basaltic magma underplating, which caused the formation of great amount of crust re-melting granitoids. This period can further be divided into two stages. The first stage （ 170 - 150 Ma） is represented by large-scale emplacement of crust re-melting granites with some tungsten mineralization at the end. The second stage （ 150 - 140 Ma） is the most important time of large-scale mineralizations of non-ferrous and rare metals, e.g. W, Sn, Nb-Ta, Bi, Mo, Be, in the Nanling Range area, although much less granitoid developed. The Late Yanshanian Period （140 -65 Ma） was generally characterized by full extension and breakup of the lithosphere of South China. However, owing to the influence of Pacific plate movement, the eastern part of South China was predominated by subduction-related compression, which resulted in magmatism of calc-alkaline and shoshonite series and related metallogeneses of Au, Ag, Pb-Zn, Cu, （Mo, Sn） , followed by extension in late stage. In the Nanling Range area, Late Yanshanian magmatism was represented by emplacement of granitic volcanic-intrusive complexes which were genetically related to volcanic-type uranium and porphyry type tin deposits, as well as mafic dykes which caused the mobilization, transportation and mineralization of uranium in pre-existing Indosinian granites. Related Articles | Metrics Cited: Baidu(259)

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Geological Process of Early to Middle Permian Magmatism in Tarim Basin and Its Geodynamic Significance YANG Shu-feng1, CHEN Han-lin1, JI Deng-wu1, LI Zhi-long1, DONG Chuan-wan1, JIA Cheng-zao2, WEI Guo-qi2 J4    Abstract （1994）      PDF （3053KB）（921）       Knowledge map    Save Through systematical research of early to middle Permian basic igneous rocks the focus on the trace element and REE geochemistry, the deposition characteristics, the source of basic igneous rocks and the deep geological process of early to middle Permian Magmatism are put forward. The basic magma originated from homogeneous enriched mantle with relatively intense differentiation. Moving up of magma resulted in fast uplift of upper lithosphere, regional uplift and recession toward west. The lithosphere of Tarim basin was broken up and large scale magmatism occurred while the uplift force exceeded the tortuosity of lithosphere. The Early to Middle Permian magmatism was related to Paleo-Tethys evolution The magmatism in Tarim basin with the Permian magmatism happened in Tarim basin, Turpan-Hami basin and adjacent area, Hongliuhe area, Beishan area and western margin of Yangzhi plate Permian, comprised an intense nmgnmtism belt in the northern margin of PaleoTethys. Related Articles | Metrics Cited: Baidu(207)

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Origin and Tectonic Setting of the Early Mesozoic Granitoids in Qinling Orogenic Belt ZHANG Cheng-li1, WANG Tao2, WANG Xiao-xia3 J4    Abstract （3564）      PDF （1737KB）（2667）       Knowledge map    Save The Early Mesozoic granitoids in Qinling Mts are characterized by the metaluminous to peraluminous and moderateto high-K calc-alkaline rocks with enrichment in LILE and LREE and poorness in HFSE, as well as relative depletion in Nb and Ta, showing the geochemical features similar to those of post-collisional granitoids. Some of them are adakite-like and rapakivitextured granitoids. The adakite-like granitoids display high Sr and low Y contents, and rapakivi-textured granitoids show transitional geochemical characters from I- to A-type granites. The structure and geochemistry of these granitic intrusions, together with the bimodal features of the coeval lamprophyres and mafic dykes, suggest that the Early Mesozoic granitoids in Qinling Mts region were formed in a post-collisional setting. The early adakite-like granitoids were formed under the thickened crust during the early post-collision period. The large numbers of normal massive granitoids were produced under the crustal extension environment after delamination in Qinling Mts region, and the occurrence of rapakivi-textured and high differentiated granitoids indicates that Qinling region had evolved into the late stage of post-collisional environment. Related Articles | Metrics Cited: Baidu(202)

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Regional Tectonic Evolution Around Yinggehai Basin of South China Sea GUO Ling-zhi, ZHONG Zhi-hong, WANG Liang-shu, SHI Yang-she, LI Hua, LIU Shao-wen J4    Abstract （1975）      PDF （3104KB）（1344）       Knowledge map    Save Yinggehai basin is located in the northwest of South China Sea， and formed in the Cenozoic The Cenozoic sedimentary thickness in the basin is more than 15km ，therefore，the structural features related to rifting phase are difficult to reveal by seismic profiling In order to understand its origin an d evolution， we analysed the regional characteristics of the Cenozoic tectonic evolution surrounding Yinggehai basin，an d obtained the Cenozoic tectonic stress field of the basin. The formation and tectonic stress field of Yingehai basin can be divided into four phases. The first phase, from the later Paleocene to the early Oligocene，Indochina block extruded toward southeast fast，with a clockwise rotation movement Yinggehai basin origined in this stage. The second phase， from the later Oligocene to the early Miocene， Indochina block’s southeastward extrusion slowed down gradually. However， South China block was relatively stable and Yinggehai basin was under a left-slip shearing condition. The third phase, during the middle and the later Miocene， with the Indochina block intruding into Eurasia plate gradually，Indochina peninsula’s extrusion slowed down further . At the end of the middle Miocene，South China block began to extrude integrally. The last phase，from the Pliocene to the Quaternary period，Indochina block was relatively stable，South China block’s extrusion continues ，the relative movement of these two blocks is right-slip shearing The Cenozoic evolution of tectonic stress field of Yinggehai basin is controlled by the interaction between Pacific plate， India plate and Eurasia plate. Most of all， the relative movement between Indochina and South China block resulted from the India-Eurasia collision is the dominate factor of the Cenozoic tectonic stress field controlling the origin an d evolution of Yinggehai basin. Related Articles | Metrics Cited: Baidu(195)

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Lithospheric Thinning Beneath North China:A Temporal and Spatial Perspective Xu Yi-gang J4    Abstract （1607）      PDF （1921KB）（1179）       Knowledge map    Save This paper reviews geochronological and geochemical data on Mesozoic -Cenozoic magmatism in North China.It is suggested that the temporal variation in geochemistry of Mesozoic-Cenozoic mafic rocks is coupled with lithospheric thinning process in this region. Consequently,the duration of magmatism(180～90 Ma)provides a first-order estimation for the timescale of lithospheric thinning in this region.The relatively long timescale(～100 Ma)suggests that thermomechanical erosion by convective mantle is the main mechanism of lithospheric thinning. Contrasting magmatic evolution trends in western and eastern North China craton suggest that lithospheric thining may have proceeded in diachronous manner. Related Articles | Metrics Cited: Baidu(194)

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Features of the Thrust Wedge of Deformation Belt in Kuqa Rejuvenation Foreland Basin LU Hua-fu1, JIA Chen-zhao2， JIA Dong1，CHEN Chu-ming1，LIU Zhi-hong1, WANG Guo-qing, WANG Sheng-li J4    Abstract （1871）      PDF （4409KB）（891）       Knowledge map    Save Kuqa rejuvenation foreland basin and its thrust wedge of foreland deformation belts are structurally responsed to the India-Eurasia collision in the interior of Asia continent Based on the detailed surface geology reconnaissance and interpretations of many seismic profiles, we conclude that thrust wedge of deformation belt in Kuqa rejuvenation foreland basin is divided into five structural units, including the marginal thrust and hidden structural zone, the Shidike anticline zone, the North linear anticline zone, the Baicheng piggy-back depression and the Qiulitage thrust fronta1 zone．The fauult-related folds aye the basic deformation styles of the rejuvenation foreland thrust wedge, which are classified into nine kinds of fault-related folds, including fault-band fold, fault propagation fold, detachment kink fold, duplex, pop up, hybrid fault-bend/detachment fold, stacked anticline, composed wedge structure and superimposed fault-lend/fault-propagation fold In the northern part of the fiat/ramp thrust wedge, the fault-related folds are mainly of fault-bend folds, fault-propagation folds, and duplexes For the very front of the wedge there exist well developed blind thrusts and detachment kink folds, forming a typically cryptic thrust wedge front edge．Growth strata recorded accurately initial emplacement ages of every structure belt and detailed forming processes．Thrusts and thrust-related folds propagate from the north to the south within the thrust wedge , i.e. Misibulake anticline initiated in the Miocene(23.3Ma), velocity of blind thrust 0.16mm/a; Kalabahe anticline and Kelasu anticline in 16.9Ma, velocity of hidden thrast 0.16mm/a and 0.16mm/a; Dawanqi anticline in 3.6Ma, velocity of hidden thrust 0.82mm/a: Dongqiulitage anticline in 3 Ma, velocity of blind thrust 1.3turn/a; and Yaken anticline in 1.87Ma, velocity of hidden thrust 3mm/a.The crustal shortening velocity which caused the thrusting is slow at about 0.355mm/a in average in the Miocene, then approaches O.82mm/a in middle Pliocene. During the late Pliocene and the Quaternary the velocity gets faster in about one magnitude order, up to 1.29-3mm/a, implicating that an accelerating crustal shorting process occurred in the late Cenozoic in the Kuqa thrust belt and approached a climax in the Pliocene and the Pleistocene. Related Articles | Metrics Cited: Baidu(152)

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Petrogenetic-Metallogenetic Background and Time-Space Relationship of the East Qinling Molybdenum Ore Belt, China ZHANG Zheng-wei1;2, ZHU Bing-quan2, CHANG Xiang-yang2, QIANG Li-zhi3, WEN Ming-xing3 J4    Abstract （1691）      PDF （2528KB）（873）       Knowledge map    Save The porphyry type molybdenum ore belt in east Qinling measures more than 200km long and 20km wide, forming a NWW-trending rectangle. Mineralizations are equidistantly distributed along NE direction like a string of beads. It is a typical crossed area of the geochemical steep-dipping zone and geo physical gradient zone. Along a plunging mantle syncline in E-W plunging direction and from the east to the west are distributed check-shaped fractures which control the synergic crust-mantle grano-porphyry rocks in the Luonan-luanchuan area. Our preliminary interpretation is as follows: The Luonan-Luan chuan area at depth wan a westward plunging mantle syncline with a nearly E-W axis direction. The geochemical boundary was controlled by the strike direction of syncline. The geophysical gradient zone was controlled by the steep slope of the syncline. The crossing effect caused the structural fracture assembly on the NNE direction a long the rigid block margin. These superimposed upon parallel fracture bunches on the ancient continental margin, which were expressed as the check-shaped distribution pattern. Under the influence of crust-mantle interaction the fluid moved up along the structures to the shallower crust and form ed mineral deposits There occurs a series of small masses of early and late Yanshanian granite porphyries, diorite and various dyke rocks of acid-intermediate compositions The main controlling factors of this porphyry molybdenum ore halt were dependent on the character of magmatic activities and conditions of occurrences. The molybdenum mineralization was closely related to the highly acidic, alkali and potash-rich Yanshanian small intrusive bodies. Both the rock-forming and ore-forming processes are structurally controlled in time and space. Related Articles | Metrics Cited: Baidu(136)

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Major Transformation of Subcontinental Lithosphere beneath North China in Cenozoic-Mesozoic: Revisited ZHOU Xin-hua J4    Abstract （1885）      PDF （946KB）（2268）       Knowledge map    Save The dramatic change of subcontinental lithosphere mantle (SCLM) beneath North China in Cenozoic-Mesozoic has been a hotly debatable issue in Earth science community. This paper presents an overview on topics related to this field, such as temporal and spatial characteristics of lithospheric transformation, progresses in geophysical and geological studies, latest applications of new analytical technology, mechanism and deep processes involved, as well as the dynamic regime in tectonics.The author emphasizes to adopt the term of transformation, instead of the term of thinning as used so far, to describe this large scale geodynamic event in East Asia. It is also noted that "the destruction of craton" is not a proper phrase for delineating such an event in North China. Meanwhile, a global link between Mesozoic mantle overturn and transformation of SCLM in eastern China has been proposed and stressed, which opens a variety of research approaches to further studies. Related Articles | Metrics Cited: Baidu(129)

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U-Pb Zircon Ages of the Eclogite and Tonalitic Gneiss from the Northern Dabie Mountains, China and Multi-Overgrowths of Metamorphic Zircons LIU Yi-can1;2, LI Shu-guang1, XU Shu-tong2, LI Hui-min3, JIANG Lai-li2, CHEN Guan-bao2, WU Wei-pin2, SU wen2 J4    Abstract （2453）      PDF （1461KB）（1123）       Knowledge map    Save The U-Pb zircon ages of the eclogite and tonalitic gneiss from the Northern Dabie Mountains were presented. The data suggest that: (1) the peak metamorphic age of the eclogite facies from the Raobazhai eclogite is 226～230 Ma; (2) the tonalitic gneiss near Ta'erhe underwent a Triassic metamorphic event; (3) zircon U-Pb ages of 226～230 Ma for the high-or ultrahigh-pressure rocks from the Northern Dabie Mountains are similar to those from the Southern UHP metamorphic belt, implying that most of eclogites or tonalitic gneiss here should be a part of Yangtze subducted continental crust and underwent a Triassic HP or UHP metamorphism; (4) the protolith ages of both eclogite and tonalitic gneiss are Late Proterozoic Era; (5) they are both affected strongly by Early Cretaceous thermal event; (6) the zircons from eclogite and gneiss have experienced two episodes of overgrowths on the margin of old zircons during the Triassic HP or UHP metamorphism and the Early Cretaceous thermal metamorphism. The overgrowth model of zircon under multi-metamorphism is very helpful to interpret the U-Pb zircon data from the high-grade metamorphic rocks. Related Articles | Metrics Cited: Baidu(124)

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The Study of Granitic Rocks in South China:Looking Back and Forward WANG De-zi J4    Abstract （1516）      PDF （3053KB）（1528）       Knowledge map    Save The past half a century has witnessed three stages in the study of granitic rocks in South China.Stage 1 began in the 1960s,focusing on the temporal and spatial distribution of granitic rocks.Based on geological evidence and isotopic dating,it was verified that there exist polycyclic granitic rocks in South China,including late Protemzoic,Caledonian,Hercynian-Indosinian and Yanshanian granitoids.It was recognized that different orogenic cycles were accompanied by corresponding granitic rocks.Generally,the age of granitic rocks tends to be younger and younger from northwest to southeast(towards the ocean side).Stage 2 was from the 1970s to the 1980s,concentrating on the petrogenic material sources of granitic rocks.Granitic rocks were classified into four types (types M,I,S and A)in terms of the mechanisms of their formation.During this period researchers also studied the tectonic environments in which various genetic types of granitic rocks were formed,as well as their petrogeochemical criteria.Stage 3 began in the 1990s and is still making progress.The research in this stage has been focusing on the relationships between crust-mantle interaction and the formation of granitic rocks,such as that between the underplating of basaltic magma and the genesis of granitic rocks,and that between magma mingling and the variation of granitic composition.The future research in this field should focus mainly on the following three topics:1.the relationships between crust-mantle interaction and the genesis of A-type granitoids;2.the mechanisms of formation of intracontinental granitic magma(metamorphic core complexes,granitic domes,and composite granitic plutons);and 3.the genesis of the great granitic provinces in South China. Related Articles | Metrics Cited: Baidu(121)

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The Geochemical Characteristics of the Early-Cretaceous Volcanics in Luzhong Region and Their Source Significances XIE Zhi, LI Quan-zhong, CHEN Jiang-feng, GAO Tian-shan J4    Abstract （1998）      PDF （1185KB）（1737）       Knowledge map    Save The sub-continental lithospheric mantle (SCLM) under the eastern part of North China was thinned and the geochemical characteristics were replaced during Mesozoic and Cenozoic. The Mesozoic SCLM under eastern Yangtze block shows the similar procedure as that in North China craton. This paper reports the geochemical characteristics of Mesozoic volcanics, which will be helpful for understanding the characteristics of Yangtze SCLM and the timespace relationship of the replacement characteristics from Mesozoic to Cenozoic. The Luzhong volcanics, occurring in eastern part of China and belonging to Yangtze block, are a set of Late-Mesozoic alkali-rich shoshonitic rocks, which include trachybasalts-basaltic trachyandesite-trachyte. The Suangmiao group, part of the Luzhong set, was studied in detail in this paper. The volcanics were slightly contaminated by crust materials during the formation, and the elemental and isotopic compositions can well reflect their mantle source. The basaltic rocks are characterized by enriched Rb, K, Sr, Th and LREE, and depleted HFSEs. They also have enriched Sr-Nd isotopic compositions with (87Sr/86Sr)i = 0.7060~0.7063，εNd(t ) = -3.9~-6.2，(206Pb/204Pb)i = 17.788~18.125，(207Pb/204Pb)i = 15.511~5.546, (208Pb/204Pb)i = 37.735~38.184. These data suggest that the magma was partially melted from enriched mantle source, which was effected by lower crust materials within the source, and followed by crystal fractionation. The magma composition and mantle source characteristics of Luzhong volcanics imply the extension of lithospheric mantle and asthenosphere upwelling in the Late Mesozoic. Related Articles | Metrics Cited: Baidu(121)

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Geochronological Sequence of Mesozoic Intrusive Magmatism in Jiaodong Peninsula and Its Tectonic Constraints ZHANG Tian and ZHANG Yue-qiao J4    Abstract （1345）      PDF （944KB）（1771）       Knowledge map    Save Jiaodong Peninsula，located in the North China Craton east of the Tanlu fault zone，is one of the most important areas of Mesozoic intrusive rocks population．A geochronological sequence of Mesozoic intrusive rocks has been established through a detailed study of high-resolution isotopic ages of intrusive plutons in this area. Three periods with different magmatisms are distinctive：the Late Triassic mantle-derived granites aged 225~205 Ma， the Late Jurassic crustal-derived S-type granites aged 160~150 Ma, and the Early Cretaceous crust-mantle mixed sourced granites aged 130~105 Ma．A comparison of geochronological framework of the Mesozoic intrusive rocks with those outcropped in Liaodong and Luxi-Xuhuai areas provides key information to constrain tectonic evolution of North China．It points out that the Late Jurassic crustal-derived S-type granites in Jiao-Liao area record an important crustal thickening event, which is considered to be geodynamically related to flat subduction of the Pacific plate beneath the Asia continent. This was followed by lithospheric delamination and attenuation during the Early Cretaceous, which resulted in widespread crust-mantle mixed sourced granitoid magmatism in East China. Crustal thickening and thinning are considered to be main cause for changes in Mesozoic tectonic regime and sequential evolution of magmatism in East China. Related Articles | Metrics Cited: Baidu(120)

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Post-Orogenic Granites with an Age of 1800Ma in Luliang Area, North China Craton: Constraints from Isotopic Geochronology and Geochemistry GENG Yuan-sheng1, YANG Chong-hui1, SONG Biao1 2, WAN Yu-sheng1 2 J4    Abstract （1899）      PDF （2936KB）（1046）       Knowledge map    Save Major trace element characteristics and zircon U-Pb SHRIMP dating of the Luyashan augite-monzonites and Yunzhongshan granites in Luliang area, Shanxi Province indicate that the Luyashan augitemonzonites and Yunzhongshan granites belong to the post-orogenic granite．Zircon grains from the Luyashan augite-diorite yield a SHRIMP U-Pb age of 1 794±13 Ma and zircon grains from the Yunzhong-shan granite a SHRIMP age of 1 801±llMa. Determination of post-orogenic granites at ca．1 800 Ma provides direct evidence for constraints on the ending time of the orogeny at the end of Paleoproterozoie． Related Articles | Metrics Cited: Baidu(119)

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Zircon SIMS U-Pb Geochronology of Host Granitoids in Wushan and Yongping Copper Deposits, Jiangxi Province DING Xin, JIANG Shao-yong, NI Pei, GU Lian-xing, JIANG Yao-hui J4    Abstract （1531）      PDF （2691KB）（935）       Knowledge map    Save Wushan and Yongping deposits are two of the most important copper deposits in the Lower Yangtz Mineralization Belt. In this study, SIMS U-Pb dating was performed on zircons from host granitoids in both Wushan and Yongping deposits, Jiangxi province. Zircons from both Wushan and Yongping deposits yield two distinct age groups. In Wushan deposit the zircon ages are 145 ±4 Ma and 121 ±3 Ma. In Yongping deposit the zircon ages are 160 ±2 Ma and 135 ±7 Ma. The zircons of earlier stage were likely formed during emplacement of intrusion, and the later ones formed during the later magmatic evolution and/or hydrothermal alteration. We suggest that the granitic magma intrusion ages of Wushan and Yongping deposits are 145 ±4 Ma and 160 ±2 Ma, respectively. These ages also represent the ore forming age for both skaru and porphyry ores that related to the intrusions of Yanshanian magmatism in these two deposits. Related Articles | Metrics Cited: Baidu(117)

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Isotopic Dating and Genesis for Fogang Biotite Granites of Conghua Area,Guangdong Province CHEN Xiao-ming, WANG Ru-cheng, LIU Chang-shi, HU Huan, ZHANG Wen-lan, GAO Jian-feng J4    Abstract （1659）      PDF （3427KB）（1630）       Knowledge map    Save Fogang(main body)biotite granites are a part of large-scaled Fogang granitic complex of east-west trending.They occupy about 85％ of the complex in area.They are composed of about 2～ 6％ biotite,35～ 41％ quartz,10～ 18％ plagioclase (An10—23)and 36～ 48％perthite,corresponding to biotite syenogranite(3a)on the basis of mineral contents by lUGS classification.The biotite has lower Mg／(Mg+Fe )values(0.17-0.21)and the K-feldspar is usually microcline perthite.Fogang biotite granites have an age of 167.5± 7.5Ma(MSWD =2.4),determineted by Rb-Sr whole rock-minera1 isochron method (emplaced during Middle Jurassic period).Similar to S type granites in south China,Fogang granites are markedly rich in silica(Si02：71.74～77.64％)and K20 relative to Na20 (averaging K2O／Na20=1.66),and are moderately peraluminous (averaging A／NKC = 1.056) and calcic-alkaline to weakly subalkaline series(NK／A=0.797 in average).Based on the trace element and rare earth element data,the granites commonly have higher Rb／Sr(1.98～ 41.71),Rb／Nb(11～23),K/Nb(1498-2976)ratios,lower Nb／Ta ratio(5.94 in average),strong to moderate Eu depletion(Eu／Eu* =0.12～0.46),and higher(La／Sm)N values(1.67～5.39).In Sr,Nd,Pb,O,isotopic composition field,Fogang granites have higher Isr (0.7116±0.0023)and εsr (t)values(96～ 103),showing that South China Upper Crust end member occupies about 66～69％ in their source materials in terms of the model calculation. The granites possess higher δ18O‰(+9.3～ +12.5)and 207Pb／204Pb(15.734)and 206Pb／204Pb(18.968～19.049) indicating that they are consistent with Upper Crust Evolution Line in the Pb-tetonic model diagram.The above mentioned data wholely indicate that Fogang biotite granites were formed by partial melting of source materials consisting of mid to lower crust rocks.Some of dark enclaves of dioritic or granodioritic compositions are found in Fogang biotite granites. This suggests that basalt underplating resulted from lithosphere westward subduction of the Palaeo Pacific plate and northward subduction of the Philippine Block,effected upon the formation of Fogang granites. Related Articles | Metrics Cited: Baidu(116)

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Post-Collision Tectonism and Basin-Range Evolution in the Tianshan Belt SHU Liang-shu1, GUO Zhao-jie2, ZHU Wen-bin1, LU Hua-fu1, WANG Bo1 J4    Abstract （2595）      PDF （3614KB）（1227）       Knowledge map    Save The sub-E-W-striking Tianshan belt was built in the late stage of Paleozoic.evidenced by Permian foreland molasses of regional scale which indicate the uplifting of Tianshan belt and formation of foreland basin.During Triassic,this orogenic belt was peneplaned,and the basins parallel to orogenic belt were further developed.In the interval of Jurassic Paleogene,extensional tectonic activity withinplate split the peneplaned Tianshan region into a series of sub-E-W-striking extensional basins.Since Neogene,a collision between Indian and Eurasian plates took place in the southem side of Tianshan belt,causing a strong intra-continental deformation characterized by thrusting and folding. This event led to coupling of ranges and basins,yielding a mosaic basin-range landform of present time.The strong thrusting influenced the orogenic belt in the hinterland.The Mesozoic-Cenozoic brittle deformation superposed on the ductile deformed Paleozoic rocks,and the transpression structures and listric faults were strongly developed.The thrusting flakes moving toward basins are very common. The distinct kinematic features occur throughout different geological units.At the same time,ranges were strongly reuplifted,and the extensional basins were converted into compression basins. Some Mesozoic coal-bearing basins in the ranges were violently uplifted to 4 000 m high,and the altitude difference between basins and ranges was increased.The step-type thrust faults and related fault folds were developed commonly in the basins. Strong fold-thrust structures occurred in the connecting zone between basins and ranges, accompanied with local sub-E-W-striking strike slip faulting.In the Tianshan region.thrusting deformation is an important basin-range coupling mechanism.The folding and faulting of Mesozoic sedimentary rocks,active faulting,Jurassic coal layer self-ignition and formation of sintered rocks were resulted from Cenozoic tectonism. Related Articles | Metrics Cited: Baidu(110)

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Geology and Zircon U-Pb Isotopic Chronology of Dantazi Complex, Northern Hebei Province LIU Shu-wen1,3, LU ¨ Yong-jun1, FENG Yong-gang1, ZHANG Chen1,TIAN Wei1,YAN Quan-ren2, LIU Xiao-ming3 J4    Abstract （1960）      PDF （2323KB）（2484）       Knowledge map    Save The Dantazi complex in northern Hebei province, located in the middle segment of northern margin of the North China Craton, consists of the tonalitic, trondhjemitic and granodioritic gneisses (TTG) metamorphosed in high amphibolite facies to granulite facies, and a supracrustal rock association of mafic two-pyroxene granulites, clinopyroxene amphibolites, garnet plagioclase fine-grained gneisses, garnet sillimanite biotite schists and minor marbles. Detailed studies in SHRIMP and LA-ICPMS zircon U-Pb isotopic chronology reveal that the Dantazi complex experienced seven stages of evolution: (1) 2 600-2 530 Ma, the formation of the country rocks of the TTG gneisses, including some mafic supracrustal rocks that might be sources of the TTG magma; (2) 2 517-2 505 Ma, tonalitic magma emplaced and crystallized; (3) 2 494-2 473 Ma, trondhjemitic magma emplaced and crystallized;(4) 2 427-2 404 Ma, the plutonic and supracrustal lithological associations in the complex were metamorphosed and deformed in high amphibolite facies to granulite facies (earlier stage) and reworked; (5) ~1 859 Ma, mafic magma emplaced, forming some mafic dykes and stocks; (6) ~1 834 Ma to 1 793 Ma, the Datazi complex experienced an intensive regional metamorphism in granulite facies (later stage); (7) ~1 730 Ma, the complex was altered by intensive activation of geological fluids. However, there is no ~300 Ma Paleozoic age record in all the samples analyzed for zircon U-Pb isotopic chronology, suggesting that the Dantazi complex did not experience the Paleozoic metamorphism. Related Articles | Metrics Cited: Baidu(106)

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SEM Study on Jarosite Mediated by Thiobacillus ferrooxidans ZHU Chang-jian, LU Jian-jun, LU Xian-cai, WANG Ru-cheng, LI Qi J4    Abstract （1311）      PDF （1986KB）（1162）       Knowledge map    Save Jarosite is a major secondary mineral formed in acid supergene environment by oxidation of metal sulphide．Thiobacillus ferrooxidans occurring extensively in metal sulphide ore district has an important effect on oxidation of metal sulphide and formation of secondary minerals．In order to discuss the effect of Thiobacillus ferrooxidans on the formation of jarosite，two parallel experiments were conducted for preparation of jarosite：chemical experiment and biologically mediated experiment．The compositions and morphological features of these two groups of jarosites have been investigated by means of XRD，SEM and EDS．The study indicates that full propagation of Thiobacillus ferrooxidans in the solution is beneficial to the formation of jarosite．The oxidation rate of Fe2+in the solution is probably the main factor that affects crystallization of jarosite．Thiobacillus ferrooxidarts induces a rapid crystallization of jarosite by increasing the supply rate of Fe2+ on the mineral surface．Jarosite mediated by Thiobacillus ferrooxidans has a better crystalline form than that synthesized by chemical method． Related Articles | Metrics Cited: Baidu(105)

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Is the Jiangnan Orogenic Belt a Grenvillian Orogenic Belt:Some Problems about the Precambrian Geology of South China Zhou Jin-cheng J4    Abstract （1385）      PDF （542KB）（2353）       Knowledge map    Save This discussion is made on the basis of age data reported in recent years of 21 century, which have been obtained by SHRIMP, LA-ICP-MS zircon U-Pb and other new dating methods. The assembly of the Yangtze and Cathysia blocks took place between 860 and 820 Ma. The continent-continent collision event forming Grenvillian orogenic belt spanned a period from 1 190 to 980 Ma. Therefore, the collision between the Yangtze and Cathysia blocks occurred about 320~160 Ma later. The basement strata in the Jiangnan orogenic belt underwent thoroughly greenschist facies metamorphism. High grade metamorphism, such as granular facies existed widely in the Grenvillian orogenic belt, has never been found in the metamorphic sedimentary-igneous rocks in the Jiangnan orogenic belt. Because of above two reasons, the Jiangnan orogenic belt should not be considered as a Grenvillian orogenic belt. It is proposed that the Jiangnan orogenic belt might be a product of collision between two neighborhood blocks during the transformation from the Rodinia to Gondwana supercontinent. The Sibao, Lengjiaxi and Fanjingshan groups in the western part of the Jiangnan orogenic belt, as basement strata, were previously believed to be Mesoproterozoic. Recent dating results of detrital zircons from the sandstones of the basement strata indicate that these strata have the maximum depositional ages of 870~860 Ma, i.e. Neoproterozoic. The S-type granites distributed along the Jiangnan orogenic belt may be considered as a petrological record of the continent-continent collisional event between the Yangtze and Cathaysia blocks rather than the products of plume magmatism. Some Neoproterozoic mafic volcanic-intrusive rocks (~760 Ma) from the western part of Jiangnan orogenic belt and the mafic rocks from the bimodal volcanic rocks (803~818 Ma) distributed around or within the Yangtze block or within Cathaysia block show some geochemical signatures of OIB. However, their exposed volumes are very small. They might have been generated in the post-orogenic extensional stage due to local upwelling of asthenospheric mantle. It is believed that they shouldn't be considered as petrological evidence of breakup of the Rodinia. Related Articles | Metrics Cited: Baidu(101)

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Zircon SHRIMP U-Pb Geochronology, Petrology and Geochemistry of the Zhujianshui Granite, Qitianling Pluton, Southern Hunan Province ZHU Jin-chu1, ZHANG Hui2, XIE Cai-fu1 3, ZHANG Pei-hua1, YANG Ce1 J4    Abstract （1775）      PDF （2127KB）（872）       Knowledge map    Save The Zhujianshui granite of Qitianling pluton is one of the granites whose emplacement age was determined isotopically by biotite K-Ar method during the early 1960＇s. Since then the Qitianling granitic pluton was considered to be Indosinian （Triassic） for many years. This paper studies the zircon SHRIMP U-Pb geochronology, petrology and geochemistry of the Zhujianshui granite, Qitianling pluton. An emplacement age of 160 ± 2 Ma was obtained which indicates an early Yanshanian （Jurassic） magmatic activity. The Zhujianshui granite is enriched in alkalies （ especially in K）, LILE＇s and HFSE＇s, and has a mantle-crustal mixed source. It was formed under a postorogenic extensional environment within the South China continent. Related Articles | Metrics Cited: Baidu(99)

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Electron-Microprobe Dating of Monazite and Metamorphic Age of Wutai Group,Wutai Mountains LIU Shu.wen1, SHU Gui-ming1, PAN Yuan-ming2, DANG Qing-ning1 J4    Abstract （2203）      PDF （1907KB）（1649）       Knowledge map    Save Electron-microprobe Th-U-Pb chemical age determination of monazite is a new in-situ geochronological method developed over the last few years.Its basic permises are that monazite contains a negligible amount of common lead and that the Th／U／Pb values are not affected by any processes excepting Th and U radioactive decay.Therefore,Th-U-total Pb chemical age of monazite Can be obtained by high-precision determination of mother and daughter elements and statistical analysis.Using the intemational standards of Th02,U metal,PbCrO4 and YAG as standards,we carried out systematic evaluation of experimental conditions and analyses for Th-U-total Pb chemical dating of monazite on a JEOL JXA-8 100 electron microprobe .Application of this electron-microprobe chemical dating of monazite from a metasedimentary rock of the Jingangkou formation,Wutai Group,Wutai Mountains yielded three distinct isochron ages:2 172±37 Ma(n=4),1 922±24 Ma (n=40), and 1 847±62 Ma(n=6).The 2 172 ± 37 Ma age.in agreement with SHRIMP U-Pb zircon ages for granitoid magnmtism in the Wutai group, appears to represent an early thermotectonic event.The 1 922±24 Ma age is within the analytical uncertainty of the metamorphic age of 1 911±38 Ma, detemfined by an internal Sm-Nd isochron of whole-rock and metamorphic minerals.Also, the 1 847 ±62 Ma age is similar to the 1 850 Ma SHRIMP metamorphic zircon ages in neighbouring Hen~han and Fuping complexes.These geologically significant results from the Wutai Group indicate that this electron-microprobe Th-U-total Pb chemical dating of monazite has obvious advantages over other geochronological methods. Related Articles | Metrics Cited: Baidu(97)

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W-Sn-Nb-Ta-Bearing Granites in the Nanling Range and Their Relationship to Metallogengesis CHEN Jun, LU Jian-Jun, CHEN Wei-Feng, WANG Ru-Cheng, MA Dong-Sheng,ZHU Jin-chu, ZHANG Wen-lan and JI Jun-Feng J4    Abstract （2794）      PDF （3275KB）（3361）       Knowledge map    Save The large-scale mineralizations of W, Sn, Nb and Ta related to granites took place in the Late Jurassic period in Nanling Range, South China. According to the petrological and geochemical features of ore-bearing granites and their relationship to mineralizations, they can be grouped into the following three major types: W-bearing granites, Sn-W-bearing granites and Ta-Nb-bearing granites. The W-bearing granites show low TiO2 and Ba+Sr contents and LREE/HREE ratios,intensive Eu depletion, high Rb and Y abundances and Rb/Sr ratios, and oversaturation in Al. They commonly underwent intensive differentiation and evolution. The Sn-W-bearing granites are characterized by enrichment of TiO2, total REE, HFSEs,Ba+Sr and Rb, higher CaO/(K2O+Na2O) and LREE/HREE ratios, metaluminous-weakly peraluminous feature and lower Rb/Sr ratios, and weaker differentiation and evolation. The Ta-Nb-bearing granites have very low TiO2, Ba+Sr, total REE and HFSEs contents and CaO/(K2O+Na2O) ratios, higher Al2O3/TiO2 and Rb/Sr ratios, higher Rb and Nb contents, and ACNK values. They are highly evolved. Good discrimination can be obtained between these three types of W-Sn-Nb-Ta-bearing granites on plots employing Nb-Y-Ce, (Ba+Sr)-Rb-(Zr+Nb+Ce+Y), LREE/HREE-Rb/Sr and LREE/HREE-(Zr+Nb+Ce+Y) diagrams. These three types of ore-bearing granites have obviously different evolutional trends. Metallogenesis is intimately related to the evolution of the ore-bearing granites. Mineralizations of Sn, W or W-Sn and Nb-Ta or Sn-W-Nb-Ta are closely related to biotite granites, twomica granites or muscovite granites and albite granites respectively. The important deposit types of W, Sn, Nb and Ta and their major features in the Nanling Range are summarized in the paper. The chloritized granite type tin deposit is proposed. This paper indicates that an attention to searching for both the chloritzed granite type tin deposits and greisen-quartz vein type W-Sn deposits in W-Sn-bearing granites in the Nanling Range should be especially paid. Related Articles | Metrics Cited: Baidu(96)

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Magmatic-Hydrothermal Evolution and Genesis of Koktokay No.3 Rare Metal Pegmatite Dyke, Altai, China ZHU Jin-chu, WU Chang-nian, LIU Chang-shi, LI Fu-chun, HUANG Xiao-long, ZHOU Dong-shan J4    Abstract （2261）      PDF （3652KB）（1436）       Knowledge map    Save The Koktokay No.3 Li-Be-Ta-Nb-Cs bearing pegmatite dyke of the Upper Paleozoic age is located in the Altai Caledonian-Hercynian fold be lt, Xinjiang Autonomous Region, China. It consists of two major parts: a gent ly dipping “plate”, and a steeply dipping cupola protruding from the plate upw ards. The overall shape of the dyke looks like a solid hat. The Koktokay pegmatite cupola is emplaced in the amphibolitized gabbro and chara cterized by a well developed internal zonal structure. From the border wall inw ards the following 9 mineralogical-textural zones can be subdivided: Ⅰ. Graphi c and pseudo-graphic pegmatite zone; Ⅱ. Saccharoidal albite zone; Ⅲ. Block y alkali feldspar zone; Ⅳ. Muscovite-quartz zone; Ⅴ. Cleavelandite-spodumene zone; Ⅵ. Quartz-spodumene (-cleavelandite) zone; Ⅶ. Thin sliced albite-mus covite zone; Ⅷ. Lepidolite-thin sliced albite (-pollucite) zone; Ⅸ. Blocky quartz and microcline core. Studies on the melt inclusions, fluid-melt inclusions and fluid inclusions in t he minerals of pegmatite provide important clues in judging the magmatic-hydr ot hermal evolution history for the pegmatite formation. The quartz, microcline, g arnet and beryl from zones Ⅰ and Ⅲ contain melt inclusions which are homogeni zed at the temperature range of 610℃～900℃. The spodumene, beryl and quartz f rom zones Ⅳ-Ⅶ contain fluid-melt inclusions and fluid inclusions. The cryst al phases in the fluid-melt inclusions comprise albite, quartz, spodumene, bery l and pollucite etc. The coexisting fluid inclusions in these minerals are of H 2O-CO2-NaCl character, with Th of 310℃～420℃. The salinities are high (wi th NaCl and/or KCl crystal) or moderate (10%～18%). The quartz from core zone contains only fluid inclusions, with Th of 300℃～320℃ and salinities of 5%～12 %. All above-mentioned temperature measurements are not pressure corrected. T he formation pressures are estimated as 3.2～1.5kb. Based on the zonal distribution and textural relationship of mineral assemblages , multiple generations of rock-forming and rare-metal minerals, as well as the features of inclusions and their thermometric data etc， it is interpreted that the zones Ⅰ, Ⅲ and partly Ⅱ、Ⅳ were crystallized from the volatile-undersa turated silicate melt; zones Ⅴ, Ⅵ and Ⅶ were crystallized from the volati le-oversaturated rare metal-rich residual silicate melt at the magmatic-hydro thermal transition stage where the residual melt phase, silicate crystal ph ase and exsolved fluid phase coexist. The blocky quartz and microcline of zone Ⅸ might be directly crystallized from the high temperature supercritical hydrot hermal solution enriched in silicate solute. The zone Ⅷ and partly zones Ⅱ an d Ⅳ might be considered as metasomatic units. However, the metasomatizing hydrothermal solutions were derived from the pegmatitic residual magma system i tself during its crystallization and evolution, but not from the outside environ ment. Related Articles | Metrics Cited: Baidu(93)

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Petrogenesis and Tectonic Setting of the Paleoproterozoic Xiong'er Group in the Southern Part of the North China Craton: a Review ZHAO Tai-ping1, XU Yong-hang1,2, ZHAI Ming-guo3 J4    Abstract （2643）      PDF （1006KB）（2082）       Knowledge map    Save The Xiong'er Group formed in 1.80-1.75 Ga of Paleo-Proterozoic and contains predominantly volcanic lavas with minor sedimentary rocks and volcanic clastic rocks (4.3% in thickness). It is the largest magmatism in scale after the formation of the crystalline basement of the North China Craton，which vary from 3 km to 7 km in thickness，and crops out over an area of 60 000 km2. The volcanic lavas are composed predomiantly of basaltic andesites and andesites, and minor dacitic-rhyolitic rocks. The volcanic lavas are lack of the rocks with SiO2 = 62% ±and therefore appear as a bimodal association. The mineral assemblage of mafic-intermediate lavas mainly contains pyroxene and plagioclase, and rarely with amphibole and bitotite. The rocks are characteristic of high Fe and K and low Al, Ca and Mg contents. All the volcanic rocks are enriched in large-ion lithophile elements (LILE, eg, Rb, Ba) and light REEs (LREE) and are depleted in high field strength elements (HFSE, e.g., Nb, Ta and Ti), suggesting an arc-related setting. The geochemical and isotopic compositions of the lavas indicate derivation from a mantle source previously contaminated by subducted material and minor crustal contamination during the upwelling of the magmas. The sedimentary rocks of the Xiong'er Group formed the Dagushi and Majiahe Formations. The rock assemblage and geochemisty of the sedimentary rocks indicate that the Xiong'er Group formed in a passive continental margin and it was mainly a marine facies when lava erupted. Therefore the paleogeographic environment of the Xiong'er Group evolved from continental facies to marine facies then to continental facies again. It is suggested that the Xiong'er Group was originated from a failed trident continental rift environment. The arc-like geochemisty resulted from an enriched subcontinental lithospheric mantle previously contaminated by subducted slab. The volcanic rocks of the Xiong'er Group is also widespread in the Baoji and Lvliang area and also appear as 1.75 Ga-old mafic dyke swarms, A-type granites, later anorthosite and rapakivi granites (1.75-1.70 Ga), and alkaline granitoids (~1.65 Ga). These intrusive rocks are assumed to have genetic link to the volcanic rocks of the Xiong'er Group. These intrusive rocks resulted from the breakup of the North China Craton, suggesting that the North China Craton was under an extention environment at~1.80 Ga. However, a detailed work is worthwhile to figure out whether a post-collision magmatism or a mantle plume that triggered the emplacement of the intrusive rocks. Related Articles | Metrics Cited: Baidu(90)

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Igneous Petrotectonic Assemblages and Tectonic Settings: A Discussion DENG Jin-fu1, 2，XIAO Qing-hui 1, 2，SU Shang-guo1, 2，LIU Cui1，ZHAO Guo-chun1，WU Zong-xu1，LIU Yong1，2 J4    Abstract （3600）      PDF （962KB）（3364）       Knowledge map    Save This paper discusses igneous petrotectonic assemblages of various tectonic settings: 1. mid–ocean ridge spreading; 2. oceanic island; 3. island arc; 4. MORS–type and SSZ–type ophiolites; 5. active coutineutal marginal arc; 6.compositional polarity of subduction–related magmatic arcs; 7. continental collision; 8. continental rift; 9. stable craton or platform, etc. It is emphasized that the tholeiitic ( TH ), calc–alkaline ( CA ) and alkaline ( A ) series defined from various parameters by different authors have different scientific meanings. In this paper it is indicated that the same written terms of TH, CA and A but with various meanings could easily result in abuse of these terms, especially for the recognition of the tectonic settings. The difference between MORS – and SSZ –type ophiolites in terms of igneous petrotectonic assemblages is discussed. The lowest MgOwt% of the HMA is suggested ( Table 2 ), based on the data of petrological experiments. The terms of magnesian andesite–dacite and adakite are discussed, and in turn, the Kay's magnesian andesite–dacite of higher Sr/Y, lower FeO/MgO, and higher MgOwt% as well as higher Ni, Cr contents, are comprehensively used, which can be more satisfactory to define the slab–melt, rather than the single parameter of high Sr/Y. The various schemes of classification for the continental collision are indicated, and it is necessary to be careful for using these schemes. The post–orogenic and the continental rifting A type granites are suggested to be associated with or without the CA/r, respectively, and the meaning of A and CA, here, is determined by the Peacock's alkali–lime index. Related Articles | Metrics Cited: Baidu(89)

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Tectonic Setting of the Northern Margin of South China Sea WU Shi-min, ZHOU Di, QIU Xue-lin J4    Abstract （2173）      PDF （2195KB）（1232）       Knowledge map    Save There are different deformation characteristics between the east and west part of the number 1 fault in the northern margin of South China Sea(SCS). The east part includes the Beibuwan basin, Qiongdongnan basin, Zhujiangkou basin and Taixi basin, with NE-EW strike segment of normal faults and traverse fold. The west part includes Yinggehai basin, with NW strike transtensiona1 faults. Based on with the features of magmatics, subsidence, sedimentary fill, crust structure in the northern margin of SCS, the authors believe that the east part margin exist three relative tectonic active periods, i.e. 40—50, 28—30, 10—5Ma. They exhibited different dynamics characteristic respectively．The former two episodes are related to the break up processing of SCS. The third is nothing to do with it. The magmatics at the northern margin of SCS are not the correspond activity with the rifting of SCS. Therefore, the east part of the northern margin of SCS belongs to the non-volcanic passive margin according to its forming mechanism. The active factors are overlapped by the interaction of surrounding plates. The west part may be related to the collision of India-Tibet and it is not a part of the northern margin based on the formation mechanism. Related Articles | Metrics Cited: Baidu(89)

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Geomicrobiology and Its Progress CHEN Jun, YAO Su-ping J4    Abstract （1389）      PDF （4947KB）（1640）       Knowledge map    Save Geomicrobiology is a new branch of earth sciences developed since the end of the twentieth century. It studies mainly the microbial processes in geologic environment and all kinds of geochemical records generated in these processes．Through microbial existence and evolution in the earth history at the various extreme environments such as high temperature，high pressure, extreme acidity and alkalinity，high salinity, very high radioactivity，large earth depth，etc．and different kinds of geochemical records in the interactions between microorganisms and their geologic environments，this discipline studies the cycling of life-essential elements(C，H，O，N，S， Fe, etc．)in the global and local scales in relation to microorganisms in the Earth’s history to set a context for further research for the microbic weathering， biomineralization，microbic ecocycling in the geologic environment and the eco1ogical environment．The present paper also concerns the interaction of microorganisms with minera1s, microbic ecology at the extreme environments，and molecular geomicrobiology． Related Articles | Metrics Cited: Baidu(88)

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Tectonothermal Evolution of the Northeastern Sichuan Basin: Constraints from Apatite and Zircon (U-Th)/He Ages and Vitrinite Reflectance Data QIU Nan-sheng J4    Abstract （1486）      PDF （1039KB）（1944）       Knowledge map    Save The tectono-thermal evolution since Triassic for the northeastern Sichuan Basin was modelled by using combined vitrinite reflectance and apatite and zircon (U-Th)/He dating methods. Corresponding to a transformation of the foreland basin during the Late Triassic to the interior cratonic basin in the Cretaceous, the paleo-heat flow was 51-66 mW/m2 during the Early Triassic. It decreased gradually to the present-day's 44.5 mW/m2. However, the heat flow increased a little at the late Cretaceous and Paleoene due to the late Yanshanian tectonic movement. At the same time, the apatite and zircon (U-Th)/He age dating revealed an uplifting of northeastern Sichuan Basin at the Late Cretaceous and the erosion could be up to more than 3000 m. The apatite and zircon (U-Th)/He ages can also provide the details of cooling history for the study area. Related Articles | Metrics Cited: Baidu(82)