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The Guangyuan Thousand-Buddha grotto is of great value in researching the spread of Buddhism in China. To explore a scientific deterioration degree evaluation method, the authors selected 11 grottos from the middle Tang Dynasty in the Guangyuan Thousand-Buddha grotto as survey objects; a traditional deterioration investigation was undertaken, and an analytic hierarchy process (AHP method) was applied to build a system to calculate the weight of 15 deterioration criteria and evaluate the deterioration degree of the grotto. The results showed that 15 deteriorations can be classified into two categories: stability deterioration and weathering deterioration. Each deterioration has its own weight on affecting the preservation condition of the grotto. In contrast to realistic conditions, the calculation results can quantitatively reflect the preservation condition of the grotto. The results offer a quantitative basis for determining the priority of grotto conservation and verifying the feasibility of the AHP method in helping conservators identify major deteriorations or judge conservation orders. This research proposes a quantitative evaluation method for the deterioration degree of the grotto, which can lay the foundation for further conservation of the grotto. [ABSTRACT FROM AUTHOR]

The principle hydrocarbon source in West Qaidam Basin, China, is the Xiaganchaigou formation, which charges a series of Cenozoic large reservoirs. We identified a series of organic-rich intervals within a sequence of Oligocene-age Xiaganchaigou evaporites in southwest Qaidam. By analyzing 2D and 3D seismic tomography and gamma ray well logs, we defined the distribution and extent of these source rocks. We also characterized their composition with trace element analysis and carbon and oxygen isotope measurements. Our data demonstrated distinctive characteristics of these source rocks with high salinity, abundant organic material, high hydrocarbon generation efficiency, and low maturity, which are associated with relatively rapid and productive hydrocarbon generation. Using high-pressure and high temperature experiments to simulate pyrolysis in samples of the source rocks, we investigated what enabled these young salt-rich source rocks to generate such an abundance of hydrocarbons. Our results highlighted the key role of saline and radioactive minerals in catalyzing accelerated pyrolysis of hydrocarbons during diagenesis and catagenesis. Salt catalysis clearly played an important role in hydrocarbon generation within lower maturity formations and also significantly improved and redefined the source rocks distribution and the extent of probable reserves in the southwest Qaidam. [ABSTRACT FROM AUTHOR]

Biogenic methane is a variety of metabolites generated by methane bacteria, consuming a simple-nutrition organic substrate under anaerobic conditions. Due to the shallow depth at which it is generally produced, biogenic methane is easily released into the atmosphere, becoming a significant contributor to the greenhouse effect. However, if suitable collection methods are employed, biogenic methane can be gathered and used as a clean and efficient energy source. The Qaidam Basin is a large saline lake basin in the Tibetan Plateau, which is rich in biogenetic gas. During the Quaternary period, the area's sedimentary center moved to the east of the Qaidam Basin. This resulted in the deposition of thick lacustrine sedimentary strata in the basin. Lacustrine mudstone is the primary source rock for biogenetic gas, and as a result, the gas is mostly found in the lacustrine strata of siltstone. In addition, evaporated lacustrine saline calcareous mudstone forms an effective covering layer for the gas. These lacustrine sedimentary strata provide both a favorable hydrocarbon accumulation environment and good preservation conditions for biogenic gas. As such, they could be converted into structural or lithologic gas reservoirs, through biogenic methane lateral migration with a suitable reservoir-cap configuration. [ABSTRACT FROM AUTHOR]

Compared to marine carbonate around the world, lacustrine carbonate is relatively scarce. Much less attention has been paid to it. Lacustrine carbonate, a product of mixed deposition of continental clastics and carbonate under special conditions, can be both important source rocks, and oil and gas reservoir rocks. Qaidam Basin is a large salt lake basin on the Tibetan Plateau where oil and gas flow has recently been discovered in lacustrine algal limestone. Study of the algal limestone is a potentially valuable target of exploration, and is of great significance to the exploration and development of mixed carbonate formations. [ABSTRACT FROM AUTHOR]