Research On The Control Of Upwelling In The Development Of Source Rocks As Exemplified By The Chinese Dalong Formation And The European Sch(?)neck Formation Shales

Organic matter in source rock is the origin of oil and gas,and the study of its enrichment law can help clarify the development mode and distribution law of highquality source rock,which has important theoretical and practical significance for conventional and unconventional oil and gas exploration.Previous studies on upwelling mostly emphasized its role in promoting the accumulation of organic matter by a single factor of increasing paleo-productivity.At present,there is a lack of systematic research on different types of upwelling,which can control the enrichment of organic matter through the synergistic influence on the paleo-sedimentary environment.In this thesis,two sets of high-quality source rocks(Dalong Formation in Sichuan Basin and Schoneck Formation in Molasse Basin,Austria)that are affected by different types of upwelling during the deposition process at home and abroad are used as the research object,using a series of inorganic geochemistry(major elements,trace elements and rare earth elements)and organic geochemistry(rock pyrolysis,pyrolysis gas chromatography,GC-MS and FT-ICR-MS)methods,with the help of multivariate statistical analysis techniques,analyze the hydrocarbon generation of two sets of shale potential,paleo-sedimentary environment and upwelling types reveal the control effect of upwelling on the process of organic matter enrichment,and summarize the trigger mechanism and comprehensive development mode of two types of upwelling:The model of hydrothermal upwelling deposition of the Dalong Formation in the Sichuan Basin:In the Late Permian,the upwelling caused by the submarine volcanic eruption in the study area carried a large amount of nutrients to the sea surface,and caused the prosperous plankton and the increase of paleo-productivity.At the same time,volcanic eruptions also caused short-term climate warming and aggravated the weathering of the land.Although the land input brought nutrients,it also changed the type of organic matter.A large number of dead plankton consumes oxygen in the process of sinking and degradation,resulting in the expansion of the intensity and scope of the oxygen minimum zone,which is more conducive to the enrichment of organic matter.Coastal upwelling depositional model of the Schoneck Formation in the Molasse Basin,Austria:The deposition period of the Schoneck Formation was at the beginning of the Quaternary Ice Age,and the global monsoon was raging.Under the action of the Coriolis force,the monsoon blows the surface water along the coast to the direction of the ocean,which in turn triggers upwelling.The cold water from the deep not only brings rich nutrients to the biological communities at sea level,but also increases the depth of the thermocline and halocline in the water body to the light euphotic zone.In short,the upwelling not only improved the ancient productivity,but also effectively enhanced the preservation conditions of organic matter.Comprehensive research shows that different types of upwelling will cause a significant increase in ancient productivity.However,the upwelling of the Dalong Formation is a heat flow,and the depositional environment is controlled by a redox environment,and appropriate terrestrial input also enhances the prosperity of paleolife.The upwelling of the Schoneck Formation is a cold flow,and the preservation conditions are controlled by the stratification of seawater because a large amount of terrestrial freshwater input will destroy seawater stratification and reduce the hydrogen index,it is not conducive to the enrichment of organic matter.