• Volume 84,Issue 1,2010 Table of Contents
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    • On the Continental Tectonics and Dynamics of China

      2010, 84(1):1-29.

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      Abstract:The Chinese continent, which is strongly constrained by the Tethyan, PaleoAsian and Pacific tectonic systems, is characterized by a complex tectonic framework and a particular lithospheric structure. Based on the theory of continental tectonics and dynamics, here we provide a comprehensive overview of recent research results with a particular attention to four important scientific problems on the Chinese (East Asian) continent. ①Tectonics of the mantle beneath the Chinese continental lithospheric plate. Seismic tomographic profiling reveals that the western Pacific slab is subducted westward to depths of 400~600km beneath the East Asian continent, and the subducted slab becomes subhorizontal and listricshaped in the mantle transitional zone. The Indian slab is subducted northward to a depth of ~800km far north under the BanggonghuNujiang sutute zong between the the Lhasa and Qiangtang terrains. Double subductions are asymmetrical beneath the western syntaxis of the Himalayan belt. In the eastern syntaxis, however, the Indian slab is subducted eastward to depths of 300~500km beneath the BurmaSanjiang terrain. ②Reactivation of the Chinese continent's metamorphic basements. Most blocks of the Chinese continent have not been reactived by significant tectonic, metamorphic or igneous events since the Phanerozoic. The north Indian and Arabian blocks (northern edge of Gondwana) were shaped by panAfrican orogenic belts at 530470 Ma. This tectonic field occurred mainly in the higher Himalaya, Lhasa terrain and Sanjiang terrain. The Cenozoic metamorphic reactivation appeared ubiquitously and uniquely in the Himalaya, Namche Barwa, Lhasa terrain and BurmaSanjiang terrain with the youngest metamorphic ages of 2~1 Ma. ③The tectonic backgrounds and processes for the formation and exhumation of HPUHP metamorphic belts in China. The eclogitebearing HPUHP metamorphic belts in China formed in either oceanic or continental deep subduction zones. Most of the oceanic HPUHP belts in the Tibetan plateau are related to the collisions of multiple small oceanic basins among multiple microcontinental blocks. Two mechanisms of the continental deep subduction are plausible: subduction drived by interblock shear collision and subduction of wedgeshaped, teared lithospheric slabs. ④Three categories of mechanisms for the extrusion of deep materials within the Chinese continental orogenic belts: constrictional extrusion; lateral extrusion; and transcompressional extrusion.

    • Metallogensis of Continental Collision

      2010, 84(1):30-58.

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      Abstract:The metallogenesis theory, based and constructed on the classic plate tectonics, has been coming to its perfection and can better explain the evolution mechanism of accretion orogenic metallogenesis and converged margin mineralization. The theory, however, fails to interpret both the collisional orogenic metallogenesis and continental collision mineralization. This study proposed a new, systematical metallogenesis theory of continental collision, herein simply named "The Metallagenesis of Continental Collision (MCC)", after the detailed research of the collisional orogeny and metallogenesis in the Tibet-Qinghai Plateau and the comparison with the Qinling orogenic belt and other collisional orogenic belts. It is suggested in the theory that the main-collisional intracontinental accretion settings, the late-collisional transitional settings, and post-collisional crustal extension setting in response to the three-stage collisional processes, are the dominant metallogenic environments of the continental collision metallogenesis and large-scale deposits. Subducted slab breakoff, asthenosphere upswelling and lithosphere dismantling and subsiding process occurring at depth in response to the three-stage collision constituted the abnormal thermal energy driving force which was responsible for large-scale mineralization. Meanwhile, the stress field evolution of transpressional and trantensional alternation or transform accompanied the three-stage collision provided the tectonic stress mechanism for the development of metallogenic system. The leading factors for the formation of metallgonesis and large-scale deposits were high-temperature fluid flows of different extents, metal-rich fluids of various origins, strike-slip -incision-detachment-thrusting structure system of various levels, as well as tensile fracture systems, all triggered by the continental collision. The crucial mechanisms for the formation of large deposits were the accumulation and sedimentation of ore-forming metals occurring in the crustal-mantle high fO2 magmatic and thermal system during the collision, fO2 magmatic-hydrothermal system during crustal anatexis, shearing metamorphic CO2-rich fluid system, as well as brine system deriving from thrusting tectonics and convection system triggered by shallow magma chamber. The MCC also put emphasis on that the whole continent collision might have triggered the three large-scale mineralizations and formed a series of indicative of large deposits. Crustal thickening and anatexis due to continental collision produced W-Sn-rich A-type granite and then formed greisen-type Sn-W deposits. Asthenosphere upwelling induced by the continental subduction slab produced metal-rich crustal-mantle mixed granodiorite, resulting in the formation of magmatic-hydrothermal-type or superimposed-type Pb-Zn-Mo-Fe deposits. CO2-rich fluid derived from metamorphic bodies due to continental collision resulted in the formation of orogeny-type Au deposits along the shearing zones while the ore-forming fluids derived from the orogenic belt formed MVT-type Zn-Pb deposits in the foreland basins. During the metallogenic period of late-collisional transform, large-scale strike-slip faulting gave rise to depressurization melting in the crust and mantle transitional zone and the enriched mantle. The exsolution of magma from the shallow crustal magma chamber produced ore-forming fluids, resulting in the formation of the porphyry-type Cu-(Mo-Au) deposits and carbonatite-type REE deposits respectively, while the Au-rich CO2 fluid derived from incising lithosphere and crustal metamorphism caused the formation of the orogeny-type Au deposits. Thrusting structure drove crustal fluid migrate and accumulated, while strike-slip pulling-apart resulted in large amount of fluids to excrete and fill, thus forming orogenic-type Pb-Zn-Cu-Ag deposits. During the post-collisional crustal extension period, shallow emplacement and fluid exsolution of the newly-born adakitic magma, resulting from the lower crust and rich in metals, water and high fO2, formed porphyry copper deposits; partial melting (magma chamber)of the middle and upper crust drove geothermal fluid system, and formed hot spring-type Cs-Au deposits in the geothermal areas, and hydrothermal vein-type Pb-Zn-Sb and Sb-Au deposits in the tectonic detachment belt.

    • Elementary Issues of Metallotectonics

      2010, 84(1):59-69.

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      Abstract:Based on the redefinition of metallotectonics, the concept system of the correlative tectonic nomenclatures of deposit was established. It is suggested that the metallotectonics refers to the geological structural units, which control the geometric configuration of orebodies, have independent natural boundary and are filled or metasomatized by orebearing substance. Based on the concept of metallotectonical unit, it is suggested that the metallotectonical series is an integration of a suit of correlative metallotectonical units forming under the same tectonic regime or some unique geologic process. The metallotectonics can be further classified into two types: the tectotype metallotectonics (tecto fracturing) resulted from the tectonic dynamic, and the hydrotype metallotectonics (fluid fracturing) from the effect of hydrokinetic force. Based on the configuration of metallotectonics, two metallotectonics mentioned above could be classified into four subtypes: brecciatype,veintype, netted veintype and disseminated type, respectively. The comparison of the differences of two metallotectonics types indicates in this study that the hydrothermaltype metallotectonics in faulting system formed commonly in the weakly deformed domains (Q domains), while the tectotype metallotectonics developed mainly in the strongly deformed belts (Pdomains). This study also discusses the relations among the deformation type, metallotectonical type and mineralization type, and indicates the existence of corresponding genetic relationship between metallotectonics and mineralization.

    • Microfossil assemblage from chert of the Ediacaran Doushantuo Formation in Zhangcunping, Yangtze Gorges, South China

      2010, 84(1):70-77.

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      Abstract:The Ediacaran is characterized by diversification of many groups in microfossils record, including filamentous cyanobacteria, multicellular algae and acritarchs. A new microfossils assemblage from the Ediacaran Doushantuo Formation at Zhangcunping, northern Yichang, China, includes filamentous cyanobacteria (Oscillatoriopsis, Polytrichoides, Salome,Siphonophycus), multicellular algae (Sarcinophycus, Wengania) and acritarchs (Appendisphaera, Ericiasphaera, Knollisphaeridium, Leiosphaena, Meghystrichosphaeridium and Tianzhushania) . Acritrachs are found at the first time in the chert nodules in this region. The new microfossil assemblage is similar to that from the member II of the Doushantuo Formation in the East Yangtze Gorges area and the upper phosphorites in Weng’an, central Guizhou.

    • Radiolarian fauna and geochemical characters of the cherts from Garze-Litang tectonic belt and its tectono-paleaogeographic significance

      2010, 84(1):78-89.

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      Abstract:The Upper Triassic Hagong Formation distributed in Shangri-La area, NW Yunnan consists of terrestrial conglomerate, sandstone, siltstone and mudstone with a lot of chaotic blocks. Chert chaotic blocks yield Middle Devonian to Middle Triassic radiolarian fauna, as well as Middle Devonian tantaculites. All the chert chaotic blocks with various ages were biogenic with Al2O3/(Al2O3+Fe2O3) ratios from 0.58 to 0.96. NASC normalized REE patterns for the chertg are relatively flat with small negative or obvious positive Ce anomaly, while without Eu anomaly, which implies the continental margin basin of depositional environment. The plankton assemblage of radiolarian and tentaculites and the geochemical features indicate that the Garze-Litang basin should have formed before Middle Devonian. The evolution of Garze-Litang basin could be divided into two stages according to the REE characters, including slowly spreading stage from Middle Devonian to early Early Carboniferous and fast spreading and subduction stage from late Early Carboniferous to Middle Triassic. There was still deep-water basin in Late Triassic, even Jurassic.

    • Characteristics of the sediments in sag-pond on the active strike slip fault and its tectonic implications

      2010, 84(1):90-105.

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      Abstract:The active faulting is closely related to the earthquake and geologic hazard. Study on the relevant deposits can help to understand the active behavior and pattern of an active fault. By disclosing the sedimentary formation of typical faulted landform, the sag-pond, can learn about the record of active strike-slip faulting by sag-ponding deposits. By disclosing a representative sag-pond with 3-D excavation along the Huangxianggou segment of the active West Qinling fault in noreastern Tibet Plateau, depositional features of the sag-pond are analized, and the sag-ponding sequence is constructed. Study shows, the stratigraphic sequence exhibits good rhythms in each pond. One rhythm is composed of the lower coarse layers and the upper fine layers, and the grain size is coarser below and finer upward. The coarse layers are commonly constituted by fine sand, coarse sand and gravels, which suggests a fast depositing. The finer layers generally consist of carbonaceous clay, mild clay and silty sand, showing characteristics of lacustrine sedimentation. The sag-ponding deposition sequence is multi-staged, and one deposition rhythm corresponds to a series of formation deposited in a period. Observations indicate that the deposition rhythms are concerned with the periodic behavior of the faulting. This study is a basis on revealing the tectonic evolution and active pattern, deducing the strike-slipping history and forecasting the future behavior of a strike-slip fault.

    • Characteristics of fluid inclusions in lacustrine hydrothermal sedimentary rock from the Xiagou Formation, Lower Cretaceous in Qingxi sag,Jiuquan basin

      2010, 84(1):106-116.

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      Abstract:Abstract: Based on the analysis of geologic background and rock fabric, the fluid inclusions in lacustrine hydrothermal sedimentary rock from the Xiagou Formation, Lower Cretaceous in Qingxi sag, Jiuquan basin is studied.The results show that, native fluid inclusions in hydrothermal sedimentary rock mainly include vapor-liquid types, in which they lack the haploid liquid and haploid vipor and triune inclusions of filial mineral are less.The mineralizing fluid is NaCl-H2O hydrothermal brine system.The temperature vary between 90℃ and 200℃, salinities between 8% and 22% NaCl eq., density between 0.99 g/cm3 and 1.2g/cm3 and mineralization pressure between 15Mpa and 180Mpa.Integrated with Sr isotope analysis, we think the mineralizing fluid is deep circular lake water with magma water, with low-mid temperature, mid-high salinity and mid-high density, and present that the temperature, salinity, density and pressure of the mineralizing hot fluid of hydrothermal sedimentary rocks contained different types of barite, ankerite and fluorite in different location decreases outwards by the order: main exhalative-channel—branch exhalative-channel—exhalative mouth—near exhalative mouth—distal basin.Based on the analysis of the characteristics of hot fluid, the mineralization mechanism of the Early Cretaceous sublacustrine hot fluid in the area is discussed.

    • Characteristics of carbonate Reservoir in Callovian-Oxfordian of samandepe gas field,Turkmenistan

      2010, 84(1):117-126.

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      Abstract:There are plenty types of carbonate sedimentary facies in Callovian-Oxfordian of samandepe gasfield, Turkmenistan. It developed five facies belts, including platform slope, platform margin reef, shallow, open platform, and restricted platform. Among of them, platform margin reef and shallow stratum are most important intervals, and mainly developed high quality reservoirs. The reservoir lithology in Callovian-Oxfordian is mainly biolithite, bioclastic limestone, ooid limestone, and the strata is relatively thick. Comprehensive utilized geology, well drilling and seismic, and according to core description, thin section analysis and precipitation facies analysis, the author researched the different types of reservoir in samandepe gas field, including pore hole fissure type, Pinhole type, fissure Pinhole type and fissure type. Pore hole fissure reservoir is developed in platform margin reef facies which formed in energetic environment;Pinhole reservoir is mainly developed in platform margin shallow which is relatively energetic;Fissue-pinhole reservoir is developed in energetic shallow environment, and open platform;Fractured reservoir is mainly distributed in low energy environment, such as, laggon and subtide. Based on that, the electrofacies response models of different reservoir types are established. The author researches control action of the developed reservoir, caused by lithology, precipitation facies and diagenesis. The conclusion is that energetic reef flat facies has the best reservoir ability, strongly compaction and cementation are the most important elements of destroying reservoir property.

    • The Sedimentary Characteristics of the Upper Devonian Tempestite and Gravity Flow and Its Geological Implications in Ziyun Area, Guizhou

      2010, 84(1):127-132.

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      Abstract:Abstract The Upper Devonian in Ziyun, Guizhou is mainly composed of carbonate rocks, several sets of gravity flow depoits and two sets of strom depoits developed in the layers. gravity flow is characterized by debris flow’s filling of multi-period calcarenite with matrix support,The strom sedimentary characteristics include erosional structures、swaley cross-bedding、graded bedding、drainage structure and et al. The research indicates that gravity flow in this area develop 3 types of depositional succession group. The 3 types of succession group indicate deeper water of palaeogeography environment, that confirms the existence of Dianqiangui Basin within platform and trench face in Devonian,the discovery of tempestite indicates study area in Late Devonian should be located in the low-latitude situation near the equator during late Devonian, the climate was warm,the water was clean.

    • A Study on Coalbed Methane Geological Characteristics and Reservoir Controlling Parameters in Tuha Coal BasinA Study on Coalbed Methane Geological Characteristics and Reservoir Controlling Parameters in Tuha Coal Basin

      2010, 84(1):133-137.

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      Abstract:China has a large amount of low-rank coalbed methane resource, coalbed methane resource existed in low rank coal below medium volatile over 15.13 trillion cubic meter. Till now, there is still no successful production, Studies on geology should be strengthened. In this paper, the authors analysized the coalbed methane forming conditions and characteristics in Tuha basin, geological settings and coal accumulation, coal series characteristics, biogenic gas preservation had also been considered. In the end, coalbed methane reservoir type and distribution patterns had been determined. Tuha coalbed methane reservoir could be divided into three types, including basin depression reservoir, basin margin steep and mild slope reservoir. In terms of matching feature characteristics of reservoir forming, two typical type can be discriminated, including reservoir forming- dissipation type and forming-migration-dissipation type. This will be an important acknowledge for low rank coalbed methane genesis and exploring.

    • Characteristics of Pathway System of Lingshui Formation of Paleogene in Deep Water Area in Qiongdongnan Basin

      2010, 84(1):138-148.

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      Abstract:Guiding by sutra stratigraphic sequence theory of Vail, used the methods of well date of border upon and seismic date of deepwater area validated one another, and carved Lingshui Formation up to four third class sequences of SⅠ, SⅡ, SⅢ and SⅣ. Then founded the three-dimensional isochronous stratigraphic sequence trellis of Lingshui Formation in the deepwater area in Qiongdongnan Basin. Detailedly studied the pathway systems of Lingshui Formation in deepwater area in Qiongdongnan Basin. Then plotted out the pathway systems to three types of reservoir, unconformity surface and fault. Used the index of carried essential and space configuration, summarized the mode of pathway systems to nine types, and combined the temperature and pressure data and fluid potential and hydrocarbon source rock of the basin, summed up two kind of hydrocarbon accumulation pattern of rift valley and half rift valley. Then it forecasted the favorableness prospecting area of Lingshui Formation in deepwater area in Qiongdongnan Basin on the base of preponderant pathway systems evaluation.

Established in 1922, Monthly

Editor in Chief :YANG Jingsui

Governing body:China Association for Science and Technology

Organizer:Geological Society of China

ISSN:1000-9515

CN: 11-2001/P

Domestic postal code:2-113

Foreign issue code:M 78

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