从地球生物学角度讨论华南中二叠世海相烃源岩缺氧沉积环境成因模式

探讨陆棚环境缺氧沉积的成因, 对查明海相优质烃源岩时空分布、恢复地史时期古环境演化具有重要意义.华南地区中二叠世栖霞组有机质丰富, 出现多方面缺氧沉积特征, 同时多门类底栖生物繁盛, 其成因一直令人困惑.简要介绍了陆棚浅海缺氧环境的生物特征及古氧相划分, 分析了栖霞组一个由纹层状灰岩和块状灰岩组成的典型的沉积序列的古氧相特征.块状灰岩的生物特征和地球化学特征均指示常氧沉积环境; 而纹层状灰岩的生物特征偏向常氧相, 沉积地球化学特征偏向厌氧相, 体现了陆棚缺氧沉积环境水体溶氧量不稳定的特点.栖霞组沉积特征表明, 栖霞组缺氧沉积环境的频繁出现与较高的生物产率有关.结合区域古地理和古特提斯古海洋背景, 认为华南地区中二叠世缺氧环境的成因与当时陆海分布格局和古海洋表面洋流系统有关.      

Depositional characteristics of Dalong Formation and its potential as hydrocarbon source rocks in Hubei,Hunan ,Guizhou and Guangxi

The Late Permian Dalong Formation in Hubei, Hunan, Guizhou and Guangxi in South China could be subdivided into several sedimentary types according to the lithology, indicative of the great spatial variations of both the lithology and sedimentary facies. The Dalong Formation deposited during the highest transgression of Late Permian, in particular under the anaerobic and suboxic conditions, which shows a strong linkage with the hydrocarbon source rocks. The Dalong Formation has some favorable properties such as hydrocarbon source rocks, including the sediments deposited in highest transgression sea level, the deep slope sedimentary environments and the low sedimentary rate, which raises the importance of the investigations on the sedimentary features, the geochemical properties and their relationship with the oil potential. __________ Translated from Earth Science—Journal of China University of Geosciences, 2007, 32(6): 774–780 [译自: 地球科学—中国地质大学学报]     

On the geobiological evaluation of hydrocarbon source rocks

Hydrocarbon source rocks are characterized by the hydrocarbon discharge, and the alteration and variation in organic compositions and organic content due to the enhanced thermal maturation. These variations throw constraints on the application of the conventional inversion evaluation of hydrocarbon potential by assessing the residual organic matter left in source rocks. Geobiology, probing the interaction between the life system and the earth system, provides new principles in deciphering the whole dynamic processes related to the organic evolution history from living biomass to organic burial. Geobiological subdisciplines, including molecular geobiology, geomicrobiology, geoecology and biogeochemistry, offer new methodology and techniques to estimate the paleoproductivity, depositional organics and organic burial capacity and their components. Geobiofacies, newly proposed herein, is terminologized to define the geobiological dynamic processes through the combination of biofacies with organic facies and sedimentary facies, and expressed by the biohabitat types, paleoproductivity, depositional and preserved organics. Geobiofacies is identified as a useful means to create the geobiological evaluation system, which in turn rectifies the conventional evaluation system for the marine source rocks. __________ Translated from Earth Science—Journal of China University of Geosciences, 2007, 32(6): 727–740 [译自: 地球科学—中国地质大学学报]     

Molybdenum isotope composition from Yangtze block continental margin and its indication to organic burial rate

The paper presents the molybdenum isotope data, along with the trace element content, to investigate the geochemical behavior of authigenic Mo during long-term burial in sediments in continental margin settings of the Yangtze block, as well as their indication to the burial of original organic carbon. The burial rate of original organic carbon was estimated on the basis of the amount of sedimentary sulfur (TS content), whilst the carbon loss by aerobic degradation was estimated according to calculated Mn contents. On these points, the original organic carbon flux was calculated, exhibiting a large range of variation (0.17–0.67 mmol/m²/day). The strong correlation between sedimentary Mo isotope values and organic carbon burial rates previously proposed on the basis of the investigations on modern ocean sediments, was also used here to estimate the organic carbon burial rate. The data gained through this model showed that organic carbon burial rates have large variations, ranging from 0.43–2.87 mmol/m²/day. Although the two sets of data gained through different geochemical records in the Yangtze block show a deviation of one order of magnitude, they do display a strong correlation. It is thus tempting to speculate that the Mo isotope signature of sediments may serve as a tracer for the accumulation rate of original organic carbon in the continental margin sediments. __________ Translated from Earth Science—Journal of China University of Geosciences, 2007, 32(6) [译自: 地球科学—中国地质大学学报]     

Chemical variation from biolipids to sedimentary organic matter in modern oceans and its implication to the geobiological evaluation of ancient hydrocarbon source rocks

Understanding the dynamics of organic matter in modern marine water columns greatly favors the geobiological evaluation of hydrocarbon source rocks. Biolipids could make great contribution to petroleum hydrocarbons due to their comparable chemical components and the slightly refractory characteristics of biolipids during the microbial/thermal degradation. A variety of environmental factors such as temperature, CO₂ and salinity could affect the biochemical contents in microorganisms. As a result, microorganisms living in a changing environmental condition might have a different contribution to the petroleum formation. Organic carbon flux is shown to bear a positive correlation with the primary productivity only within a certain range of biomass volumes in a specific biohabitat. Furthermore, organic matter is degraded much quickly in a water column with oxic conditions. Therefore, the anoxic condition, along with the enhanced biological productivity, would be one of the significant factors in the formation of high-quality hydrocarbon source rocks. The formation of biofilms and microbial mats favors the preservation of sedimentary organic matter by decreasing the degradation rate of organic matter. Identification of biofilms and microbial mats in sedimentary rocks will thus greatly help to understand the depositional processes of organic matter finally preserved in hydrocarbon source rocks. __________ Translated from Earth Science—Journal of China University of Geosciences, 2007, 32(6): 748–754 [译自: 地球科学—中国地质大学学报     

Tectonic and eustatic control on the distribution of black-shale source beds in the Wufeng and Longmaxi formations (Ordovician-Silurian),South China

It is known that high-quality, black-shale source rocks occur in the uppermost Ordovician Wufeng Formation and in the lowermost Silurian Longmaxi Formation in South China. Hence, it is important to understand their lithostratigraphy and the controls on their deposition. A review of lithostratigraphic criteria for subdividing the two adjacent formations provides new regional correlations between the formations and related stratigraphic successions and facies. Both the black shales and the related, overlying flysch deposits at the Ordovician-Silurian transition in South China appear to have migrated northwestward in time and space, reflecting probable flexural control in a foreland basin that developed in response to subduction-type orogeny southeast of the Yangtze block. The black shales also contain K-bentonites from explosive, felsic-intermediate volcanism, the distribution of which also supports orogeny to the southeast. Finally, the analysis of sequence stratigraphy, which shows that the initiation of transgressive system tracts (TST) and condensed section (CS) in the related third-order sequences coincided with the two black-shale horizons respectively, indicates that the main controlling factors for the deposition of the Ordovician-Silurian black shales in South China are (1) northwestwardly migrating, foreland-basin subsidence caused by deformational loading related to episodic accretion of the Cathaysia block to the Yangtze block during this period, and (2) the anoxic, sediment-starved water column caused by rapid rise of the sea-level during the two successive phases of third-order global sea-level rise near the Ordovician-Silurian transition in South China. In future exploration for hydrocarbon source rocks in the area, it is important to consider likely flexural and eustatic causes for subsiding, deep, anoxic seas in recognizing other source rock intervals, and our understanding of the Wufeng and Longmaxi formations may serve as models for future source rock exploration. __________ Translated from Earth Science—Journal of China University of Geosciences, 2007, 32(6): 818–827 [译自: 地球科学—中国地质大学学报]     

Calci-microbialite as a potential source rock and its geomicrobiological processes

The calci-mircobialite is a special carbonate buildup, which is formed due to the activities of different kinds of microbes. Abundant microfossils preserved in the microbialite show the high-level productivity during deposition, while characteristic sedimentary minerals and geochemical compositions suggest an anoxic marine environment for organic burial. The high-level productivity and anoxic sedimentary environment favor the efficient preservation of organic matter and thus the formation of source rocks. On these points, microbialites could be one of the potential hydrocarbon source rocks, awaiting further geobiological investigation and exploration. Precambrian and some of the great transitional stages in Phanerozoic are critical periods when microbialites were well developed. Widespread microbialites have been found in North and South China. Bitumen observed in many outcrops of Precambrian and late Devonian microbialites further raises the possibility of the calci-microbialite as a potential hydrocarbon source rock. __________ Translated from Earth Science-Journal of China University of Geosciences, 2007, 32(6): 797-802 [译自: 地球科学-中国地质大学学报]     

Petrochemistry of peridotites from North China: Significance for lithospheric mantle evolution

A petrochemical analysis was undertaken of peridotitic xenoliths in volcanic rocks that erupted from the Paleozoic to the Cenozoic within the eastern part of the North China craton, and the peridotites as tectonic intrusion in the Early Mesozoic from the Sulu orogen. The results show that the cratonic mantle, which was refractory and existed when the kimberlites intruded in the Paleozoic, had almost been replaced by the newly accreted fertile lithospheric mantle during the Mesozoic-Cenozoic. The erosion, metasomatism, and intermingling caused by the accreted asthenospheric material acting on the craton mantle along the weak zone and deep fault (such as the Tanlu fault) in the existing lithosphere resulted in the lithospheric thinning at a larger scale 100 Ma ago (but later than 178 Ma). The largest thinning would be in the Eogene. The upwelling asthenospheric material transformed into accreted lithospheric mantle due to the asthenospheric temperature falling in the Neogene (leading to relatively slight lithospheric incrassation), and finally accomplished mantle replacement. The peridotitic body in the Sulu orogen represents the products spreading from the modified cratonic lithospheric mantle. Translated from Earth Science—Journal of China University of Geosciences, 2006, 31(1): 49–56 [译自: 地球科学—中国地质大学学报]     

Potential contributions of extremophiles to hydrocarbon resources in marine extreme environments:A review

To understand the potential mechanism of marine extremophiles participating in the formation and the evolution of hydrocarbon resources in marine extreme environments, some typical kinds of extremophiles and their distributions in marine hydrothermal and cold vents are discussed and evaluated respectively. The potential relationship between extremophile activities and hydrocarbon resources in marine extreme environments are then discussed in details. It could be now preliminary concluded that archaea and bacteria are the two main kinds of extremophiles in marine extreme environments. The dominating microbe communities in hydrothermal vents are heterotrophic zymogens, sulfate reducers and methanogens, while the ANME-2 group (Methanosarcinales) surrounded by sulfate-reducing bacteria and ANME-1 group dominate in cold vents. Marine extremophiles would be able to use CH₄ and H₂S to synthesize energy for metabolism and to support food chains for other unique macrobiota nearby, which together present a high abundance but a low diversity with distinct characteristics of horizontal and vertical distributions. Marine extremophiles might play an important role either directly or indirectly in the processes of hydrocarbon formation and subsequent alteration, and could indicate the evolution of hydrocarbon resources in marine extreme environments. Our research thus has a great significance both in theoretical approach of potential hydrocarbon resources formed by marine extremophile activities and in practical exploration of the potential hydrocarbonsource sedimentary layers formed in the Earth history or the potential strata in southern China. __________ Translated from Earth Science—Journal of China University of Geosciences, 2007, 32(6): 781–788 [译自: 地球科学—中国地质大学学报]     

南华海泥盆纪烃源岩的古氧相和缺氧环境模式——以广西中、上泥盆统为例

缺氧条件是形成和保存优质烃源岩的重要条件。古氧相的研究对查明海相优质烃源岩时空分布、恢复地史时期古环境演化具有重要意义。泥盆纪时期,南华海受陆内裂陷作用影响,形成台地(滨岸台地和孤立台地)与台沟间列的盆地格局。不同的控制因素控制了古氧相的类型。在台沟和钦防裂陷海槽中,海水分层控制了泥盆纪的古氧相类型和变化。台沟和钦防裂陷海槽以厌氧相与准厌氧相为主。在台地相区,海平面变化控制了古氧相的类型和分布。台地相区的古氧相主要是常氧相和贫氧相。南华海中、晚泥盆世硅质沉积、磷质沉积发育,有机质丰富,形成了有机质-硅质-磷质沉积三位一体的特征,指示上升流作用明显。南华海地区泥盆纪位于赤道附近的信风带,向西的表面洋流越过南华海在西部形成离岸流,海底海水向东补充形成上升的底流,也说明了泥盆纪南华海上升流存在的可能性。     

Late Oligocene sedimentary environments and provenance abrupt change event in the northern South China Sea

A significant change in composition was recorded in late Oligocene sediments from the northern South China Sea. This abrupt event coincided with the seafloor spreading axis jump across the Oligocene/Miocene boundary, leading to sedimentation breaks and slumps as well as obvious changes in sediment geochemical composition, and representing the greatest tectonic activity in the South China Sea region since the Oligocene. Through this tectonic event, the sedimentary environment in the Baiyun sag area transformed from a continental shelf in the late Oligocene to a continental slope since the early Miocene, the provenance of the sediments changed from neighboring areas to the hinterland of the South China block, and the sea level rose since the early Miocene in the area. Therefore, this abrupt change event has a profound influence on the evolution of petroleum offshore in the northern South China Sea. __________ Translated from Geology in China, 2007, 34(6): 1022–1031 [译自: 中国地质]     

Study on the restitution coefficient of original total organic carbon for high mature marine source rocks

On the basis of the results of hydropyrolysis simulations for about 90 different types of immature to mature source rocks selected from about 5 000 marine source rocks in China, along with the natural thermal evolution profiles, the following conclusions were obtained. (1) Total organic carbon (TOC) content of excellent marine source rocks does not change obviously when Ro < 0.8% or Ro > 1.3%, and the residual TOC content is decreasing gradually with the maturity increase at 0.8% < Ro < 1.3%. (2) At the high-post mature stage (Ro > 1.3%), the decreased maximums of residual TOC content for the kerogen of sapropel (I), II₁, and II are usually 40%, 32% and 24%, respectively, and their TOC restitution coefficient is, respectively, 1.68, 1.48 and 1.32. (3) Both the TOC decreasing amplitude and the restitution coefficient decrease gradually with the decrease of TOC content for the source rocks with low organic matter abundance (usually 0.3% < TOC < 1.0%). The TOC restitution coefficients are, respectively, 1.20 and 1.0, when 0.3% < TOC < 0.5% and TOC < 0.3%. (4) TOC_res of solid bitumen and shale with high organic matter abundance (TOC > 30%) also require no restitution at the high mature stage. Such kind of TOC restitution is further supported by the coincidence of the decrease of residual TOC with the decreasing of S₁ + S₂ and the increasing of hydrocarbon quantity during the experimental simulation of hydrocarbon generation and expulsion for marine source rocks (0.3% < TOC < 30%) in natural thermal evolution profiles. __________ Translated from Earth Science—Journal of China University of Geosciences, 2007, 32(6): 853–860 [译自: 地球科学—中国地质大学学报]     

Features of faults in the central and northern Tibetan plateau based on results of INDEPTH (III)-MT

The features of the faults in the central and northern Tibetan plateau are discussed, based on two super-wide band magnetotelluric (MT) sounding profiles belonging to the INDEPTH (III)-MT project, which were finished between 1998 and 1999: one is from Deqing to Longweicuo (named line 500), the other is from Naqu to Golmud (line 600). This work assists research on the collision and subduction mode between the India and Asia plates. The MT results show that there is a series of deep faults, F1 to F10, in the central and northern Tibetan plateau. Of these faults, F2 is an earlier main fault which leans to the north, and F1 is a later main overriding fault. The Jiali deep fault zone, which has a very complex space structure, is composed of these two faults. F3, F4 and F5 are super-deep faults. They are high-angle faults and lean a little to the south. The main fault zone of the Bangong-Nujiang suture is composed of these three faults. Because of later activity in the structure, several shallow faults formed in the upper crust within the Bangong-Nujiang suture. The Tanggula fault zone is composed of two main faults, F6 and F7, and a series of sub-faults. The shallow segments of the main faults are in high angles and the deep segments of main faults are in low angles. These two faults generally lean to the south and extend into the lower crust. The Jinshajiang suture is composed of the Jinshajiang fault (F8) and the Kekexili fault (F9), and there is a series of sub-faults in the upper crust between these two faults. The Jinshajiang suture is a very wide suture caused by continent-continent collision. The Middle Kunlun fault (F10), which is the main structure of the Kunlun fault zone, is a high angle, super-deep fault. It is the north boundary of the Songpan-Ganzi-Kekexili block. Based on the conductive structure of the profile, the southern part of the Middle Kunlun fault belongs to the Tibetan plateau, but it is not certain whether the northern part of the Middle Kunlun fault belongs to the Tibetan plateau. There are conductive bodies stretching from the crust into the upper mantle below the Bangong-Nujiang suture and Jinshajiang suture. This may suggest heat exchange between the crust and mantle. Translated from Earth Science—Journal of China University of Geosciences, 2006, 31(2): 257–265 [译自: 地球科学—中国地质大学学报]     

Pressure evolution and hydrocarbon migration in the Baiyun sag, Pearl River Mouth basin, China

The Pearl River Mouth basin is one of the most important offshore basins in China. Petroleum exploration in the deep-water area is to start in the Baiyun sag in the basin. Due to the high cost of exploration in deep-water areas, the hydrocarbon migration and pressure evolution needs to be thoroughly probed before any actual exploration is to be done. Drilling results have indicated that the pore pressure is hydrostatic in shallow-water area. The mud diapirs found in the Baiyun sag indicate that there may be overpressure in the deep-water area. At present, little is known about hydrocarbon migration and pressure distribution in deep-water areas. On the basis of geological data from wells and basin modeling, the research comes to the following conclusions. (1) At least three episodic accumulations and releases of pressure had happened in the Cenozoic, which were closely related to the three regional tectonic movements: the Zhu-Qiong movement in the Late Eocene, the Nanhai movement in the Middle Oligocene and the Dongsha movement between the latest Middle Miocene and Late Miocene. The pressure release and associated hydrocarbon migration occurred primarily during the Dongsha movement, when most of the overpressure was released to hydrostatic pressure except for some overpressure in the deep-water area. (2) Both the measured pressure and the modeling results indicate that the pore pressure is hydrostatic pressure in the shallow-water area. Abnormally high pressure in the deep-water area is noted to be present. The difference of pressure distribution is caused by the lithologies, facies and faults. (3) The diapirs in the deep water cannot be driven by the overpressure because the maximum pressure is less than 9.0 MPa in the course of pressure evolution. (4) The fluids migrated to the shallow-water area and deep-water area along faults. Some faults connected the deep-water fans with the hydrocarbon source. Huge oil and gas fields may be formed in the deep-water area more favourably than in the shallow-water area. Translated from Earth Science-Journal of China University of Geosciences, 2006, 31(2): 229–236 [译自: 地球科学—中国地质大学学报]     

Organic fraction of the total carbon burial flux deduced from carbon isotopes across the Permo-Triassic boundary at Meishan,Zhejiang Province,China

By combining the carbon cycle model with the records of carbonate and organic (kerogen) carbon isotope, this paper presents the calculation of the fraction of organic carbon burial (f _org) of beds 23–40 at the global boundary stratotype section and point (GSSP) of the Permian-Triassic boundary at Meishan, Zhejiang Province. The resulting calculation produces two episodes of f _org maxima observed to occur at beds 23–24 and 27–29, which respectively corresponds to the two episodic anoxic events indicated by the flourish of green sulfur bacteria. Two episodic f _org minima occurred at beds 25–26 and 32–34, generally coincident with the flourish of cyanobacteria (bed 26 and upper part of beds 29 to 34) as shown by the high value of 2-melthyhopnoanes. It appears that the f _org is related to the redox conditions, with greater f _org values observed under the reductive condition. The relationship between f _org and the total organic carbon (TOC) content was complex. The f _org value was low at some beds with a high TOC content (such as bed 26), while high observed at some beds with a low TOC content (e.g. bed 27). This association infers the important contribution of primary productivity to the TOC content. The original organic burial could be thus calculated through the configuration of the function of the primary productivity and f _org, which can be used to correct the residual TOC measured today. This investigation indicates that compiling the organic-inorganic carbon isotopes with the carbon cycle model favors to understand the fraction of organic carbon burial, providing information for the reconstruction of the coupling among biota, environments and organic burial. Journal of China University of Geosciences, 2007, 32(6): 767–773 [译自: 地球科学—中国地质大学学报]     

Sporopollen and algae research of core B106 in the northern South China Sea and its paleoenvironmental evolution

Based on the high-resolution sporopollen and algae research of the sediments from core B106 in the northern South China Sea, three sporopollen assemblage zones have been distinguished in ascending order: Zone 1 (294–194 cm): Pinus-Quercus (evergreen)-Gramineae-Polypodiaceae- Pterdium-Dicranopteris. Zone 2 (194–94 cm): Pinus-Quercus (evergreen)-Polypodiaceae-Pteridium- Dicranopteris. Zone 3 (94–4 cm): Pinus-Polypodiaceae-Pteridium-Quercus (evergreen)-Dicranopteris. The three sporopollen zones correspond to three stages of vegetation, climate and paleoenvironment evolution of the northern part of the South China Sea since 11 000 years ago. Combined with AMS ¹⁴C dating, the sporopollen and algae data can be a scientific basis for stratigraphic division and reconstruction of paleoclimate and paleoenvironment in the South China Sea. __________ Translated from Marine Geology & Quaternary Geology, 2007, 27(5): 9–14 [译自: 海洋地质与第四纪地质]     

Progresses in the ice formation of glaciers in China

Glaciers, formed by snowfall and characterized by movement and size, are the most sensitive indicators to climate change. The ice formation of glaciers (the processes, mechanisms and results of transformation from snow to ice) can indicate the growth condition, the formation process and the physical characteristics of glaciers. Its spatial variation can also reflect glacier change, and further reveal climate change. Studies on ice formation of glaciers in China were initiated in 1962, when Xie and others studied the ice formation of Glacier No.1 at the Urumqi River head, Tianshan Mountain. Other researchersfollowed suit and did studies on ice formation of glaciers in Qilian Mountain. As time goes by, the concept of ice formation came into being in China. This paper reviews the development history of glacier zones, and the studies of ice formation of glaciers in China since the 1960s. These studies mainly focus on Qilian Mountain, Tianshan Mountain, Altay Mountain, and the western Kunlun Mountain, Himalaya Mountain, the southeastern Tibetan and Hengduan Mountains. The paper also discusses the significance of ice formation studies, the limitation and deficiency of previous studies, and the prospects and suggestions for future studies. __________ Translated from Advances in Earth Science, 2007, 22(4): 386–395 [译自: 地球科学进展]     

Oil geologic anomaly in the north edge of the Middle and Lower Yangtze areas based on the evidence weight method

The study of oil geologic anomalies is a new area of petroleum geology. Using the evidence weight method, we selected tectonic, hydrocarbon abundance of source rock, thickness of source rock, level of reservoir, complexity of reservoir, degree of mineralization of formation water as the evidence layer to evaluate the favorable zones of pool forming in the Lower Paleozoic in the north edge of the Middle and Lower Yangtze areas. Finally, we integrated our results with the petroleum geology of this area and concluded that the North Sichuan basin, the western area of Hubei and the eastern area of Chongqing and parts of the Lower Yangtze are the most profitable areas for exploration in the north edge of the Lower and Middle Yangtze areas. __________ Translated from Journal of Jilin University (Earth Science Edition), 2007, 37(3): 458–462 [译自: 吉林大学学报(地球科学版)]     

Discoveries of new Longfengshaniaceae from the uppermost Ediacaran in eastern Yunnan, South China and the significance

A morphologically more diverse assemblage of Longfengshaniaceae has been found in the uppermost Ediacaran (Sinian) Jiucheng Member, Yuhucun Formation at Jinning and Jiangchuan, eastern Yunnan, South China. A majority of them are different from the Longfengshania found in the Neoproterozoic Changlongshan Formation, Yanshan Mountain area, North China and the Little Dal Group, North America. They are mainly characterized by a more varied, often thallus-like appearance with no branches, such as oval, pyriform, spindle, shovel, heart, ribbon and balloon shapes, and more sturdy stalk-like projection (stipe) with a smooth connection on the basal part of the thallus. In addition, they appear to have a remarkable attaching organ of lanceolate, shuttle-like or short stem-like structure at the base of the stipe. Six distinct morphological taxa are recognized, including one new genus, two new species and three conformis species. The characteristics of the family and the genus Longfengshania are further discussed in this paper. The new discoveries of these carbonaceous macrofossils identified as Longfengshaniaceae algae on the basis of the diagnostic forms and anastomosis patterns of their thalli and stipes demonstrate that an important evolutionary radiation of metaphytes took place in the last Ediacaran stage. The flourishing of the benthonic thallophytes attached to the substrate from eastern Yunnan and considered to be photosynthetic alga probably provided continuous nutritional habitats for the explosion and diversification of the Early Cambrian “Chengjiang biota”. Translated from Acta Geologica Sinica, 2006, 80(11): 1643–1649 [译自: 地质学报]     

Distribution, migration and derivation of Mesozoic-Cenozoic regional fault systems in the central continental margin of eastern China

Deep-large faults in the central continental margin of eastern China are well developed. Based on the regularity of spatial and temporal distribution of the faults, four fault systems were divided: the Yanshan orogenic belt fault system, the Qinling-Dabie-Sulu orogenic belt fault system, the Tanlu fault system and the East China Sea shelf basin-Okinawa trough fault system. The four fault systems exhibit different migration behaviors. The Yanshan orogenic belt fault system deflected from an EW to a NE direction, then to a NNE direction during the Indo-Chinese epoch-Yanshanian epoch. The thrust-nappe strength of the Qinling-Dabie orogenic belt fault system showed the tendency that the strength was greater in the south and east, but weaker in the north and west. This fault system faulted in the east and folded in the west from the Indo-Chinese epoch to the early Yanshanian epoch. At the same time, the faults also had a diachronous migration from east to west from the Indo-Chinese epoch to the early Yanshanian epoch. On the contrary, the thrust-nappe strength was greater in the north and west, weaker in the south and east during the late Yanshanian epoch-early Himalayan epoch. The Tanlu fault system caused the basin to migrate from west to east and south to north. The migration regularity of the East China Sea shelf basin-Okinawa trough fault system shows that the formation age became younger in the west. The four fault systems and their migration regularities were respectively the results of four different geodynamic backgrounds. The Yanshan orogenic belt fault system derived from the intracontinental orogeny. The Qinling-Dabie-Sulu orogenic belt fault system derived from the collision of plates and intracontinental subduction. The Tanlu fault system derived from the strike-slip movement and the East China Sea shelf basin-Okinawa trough fault system derived from plate subduction and retreat of the subduction belt. Translated from Journal of Jilin University (Earth Science Edition), 2005, 35(5): 554–563 [译自: 吉林大学学报 (地球科学版)]