The formation mechanism of sepiolite and its application in geology

Key words: 
• Seafoam /
• Geological characteristics /
• Genetic mechanism /
• Sedimentation-rock formation /
• Geological applications

Abstract: [Significance] As a kind of autogenous clay mineral with a unique fibrous crystal structure,sepiolite plays an important role in the geological field with its excellent high adsorption and thermal stability.[Progress]The formation mechanism of sepiolite is complex and diverse, including direct precipitation,terrigene transport and sedimentation-diagenesis.This process is not only significantly affected by geological environment and climate conditions,but also intertwined with multiple factors such as element concentration and pH,which jointly shape the unique distribution pattern of sepiolite in nature.Sepiolite is mainly formed in the alkaline reduction environment rich in magnesium and silicon and poor in aluminum,and with the passage of time and the dynamic change of temperature and pressure,phase transition occurs and transforms into talc or montmorillonite and other minerals, thus forming a rich and diverse sedimentary-diagenetic evolution model.In terms of geological applications, sepiolite can efficiently adsorb a large amount of organic matter with its excellent adsorption properties,providing a material basis for the formation of unconventional oil and gas reservoirs, and significantly improving the quality of source rocks and hydrocarbon generation potential.In addition,sepiolite can also promote the dolomitization of high limestone,and then transform into high-quality dolomite reservoir,and breed two novel hydrocarbon accumulation modes:natural self-storage and lower and upper storage.By studying the thickness and distribution of sepiolite strata,we can infer the fluctuation characteristics of palaeogeomorphology, and then predict the favorable distribution area of oil and gas reservoirs,which provides important geological basis for oil and gas exploration.At the same time, the formation and distribution of sepiolite can also reflect various paleoenvironmental information such as evaporation system,water level change,climatic conditions and anoxic environment,and reveal major geological events.[Conclusion and progress]Therefore, sepiolite shows important research value in oil and gas exploration, paleogeomorphology reconstruction and paleoenvironment restoration.The future development trend of sepiolite will be to use sepiolite to obtain ancient environmental conditions,improve the ability to analyze seismic data of the thickness of sepiolite layer,and develop the exploration of oil and gas in sepiolite layer.