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Using analyses of the lithology, sequences, paleoenvironment, and tectonic setting, the depositional system of the Carboniferous Huanglong Formation in the eastern Sichuan Basin was identified. The lithological characteristics of the Lower Member, Middle Member, and Upper Member were analyzed and classified. Before the use of carbon, oxygen, and strontium isotopes in the analysis, all of the geochemical data were tested for validity. On the basis of the Z values obtained from carbon and oxygen isotopes, the paleoenvironments of the three members were elucidated. Lower Member was dominantly an enclosed marine environment with intense evaporation and little freshwater input into the sea. Middle Member developed in a semi-enclosed to normal marine environment with many rivers. Upper Member was formed in a normal marine environment. The east Sichuan Basin was enclosed by paleouplifts before the deposition of the Huanglong Formation, forming a relatively enclosed depositional setting. Paleogullies developed in the Silurian strata that underlie the Carboniferous rocks; these paleogullies can be identified. On the basis of a comprehensive analysis, we propose that the Huanglong Formation developed in a platform system. Four microfacies were identified: supratidal flat, dolostone flat, grain shoal, and shelf microfacies. The high-permeability and high-porosity characteristics of the grain shoal microfacies are favorable for hydrocarbon accumulation, while the supratidal flat and shelf microfacies developed very few high-quality reservoirs. The paleogullies, in which increased amounts of grain shoal microfacies developed, controlled the distribution of high-quality reservoirs. [ABSTRACT FROM AUTHOR]

A comprehensive compilation and systematic analysis of known early and middle Permian brachiopod faunas shows that the early Permian brachiopod faunas comprise three realms, six regions, and eleven provinces, while those of the middle Permian comprise three realms, four regions, and eight provinces. A comparison and analysis of brachiopod faunal patterns reveal a coevolution between global brachiopod paleobiogeography and tectonopaleogeography during the early-middle Permian. Although temperature/latitude is the main factor controlling the formation of three realms, tectonopaleogeographic factors determine the temperature/latitude in which the continents were located. The 'continental barrier' of Pangea, as a 'central axis' continent, divided the three realms into six regions, which indicates that the formation of biogeographic regions was controlled mainly by the tectonopaleogeographic factors. The evolution of tectonopaleogeography was sometimes a long-term process, so that the biogeographic regions (or provinces) controlled by tectonopaleogeography displayed relative stability. Shifts in the nature of biogeographic provinces (e.g., from cool water to warm water, and vice versa), extensions or narrowing of geographical ranges, and recombinations of some provinces were all related to regional tectonic evolution. The study of the coevolution between brachiopod paleobiogeography and tectonopaleogeography not only accounts for the formation mechanisms of brachiopod paleobiogeographic patterns during the early-middle Permian, but also provides evidences for the locations and configurations of oceans and plates (blocks) during this period. [ABSTRACT FROM AUTHOR]

Quantitative studies on the extension and subsidence of the Wanan Basin were carried out based on available seismic and borehole data together with regional geological data. Using balanced cross-section and backstripping techniques, we reconstructed the stratigraphic deposition and tectonic evolution histories of the basin. The basin formed from the Eocene and was generally in an extensional/transtensional state except for the Late Miocene local compressoin. The major basin extension ocurred in the Oligocene and Early Miocene (before ∼16.3 Ma) and thereafter uniform stretch in a smaller rate. The northern and middle basin extended intensely earlier during 38.6-23.3 Ma, while the southern basin was mainly stretched during 23.3-16.3 Ma. The basin formation and development are related to alternating sinistral to dextral strike-slip motions along the Wanan Fault Zone. The dominant dynamics may be caused by the seafloor spreading of the South China Sea and the its peripheral plate interaction. The basin tectonic evolution is divided into five phases: initial rifting, main rifting, rift-drift transition, structural inversion, and thermal subsidence. [ABSTRACT FROM AUTHOR]

Precambrian tectonic history of Zhejiang, Fujian, and Jiangxi provinces of south China is important for understanding the tectonic evolution of South China but its magmatic activity, petrogenesis, stratigraphic sequence of the Mamianshan Group is still strongly controversial. Here we present new sensitive high resolution ion micro-probe (SHRIMP) U-Pb zircon geochronological data for the Mamianshan Group and petrographical data to constrain the tectonic framework of the regions. Our results showed that the SHRIMP U-Pb zircon age of green schists of the Dongyan Formation is 796.544.3 Ma, the Daling Formation is 756.2±7.2 Ma, and mica-quartz schist of the Longbeixi Formation is 825.5±9.8 Ma. These data indicate that the Mamianshan Group was formed not in the Mesoproterozoic, but in the Neoproterozoic and its stratigraphic sequences should be composed of Longbeixi, Dongyan, and Daling Formations from the bottom to the top. Rocks from this Group, from Zhejiang, Fujian and Jiangxi provinces, constituted the upper basement of the Cathaysia Block that overlay the lower basement of the Mayuan Group. Detailed petrographic studies demonstrate that the amphibole schists of the Dongyan Formation in the Mamianshan Group were formed within an intra-arc rift setting rather than a continental rift as previously suggested. Rather, this island-arc type formation was developed by collision and/or subduction between various blocks resulting from the breakup of the supercontinent Rodinia at c.850-750 Ma. The Zhuzhou conglomerate, distributed near Dikou Town, Jian'ou City, Fujian Province and previously considered as evidence of the Mesoproterozoic Dikou movement, is shown here not to be the basal conglomerate above the angular unconformity between the upper and lower basements. Our conclusions have important implications for understanding the Precambrian tectonics of South China. [ABSTRACT FROM AUTHOR]