The Chemical Statigraphic Framework And K/Pg Boundary Of Jiaoke 2 Well

The Jiaolai Basin is located in eastern China which is a typical Mesozoic faulted basin.Due to the complete development of the Cretaceous and Paleogene strata,and the abundant paleontological and geochronological data,the study of the terrestrial K/Pg boundary has been carried out here.In order to obtain a complete sedimentary record,the Jiaoke 2 well was drilled on the west side of Jiaozhou City in the Jiaolai Basin,and the core of Jiaozhou Formation in the upper part of the Wang Group was drilled to provide materials for subsequent research work.Using the obtained geochemical data to conduct chemostratigraphy research on the core of Jiaoke 2 Well,using principal component analysis and ordered clustering methods,the core of Jiaoke 2 Well was divided into 10 secondary stratigraphic units,established a chemical stratigraphic framework.The climatic stratigraphic analysis of the core of Jiaoke 2 well combined with the method of frequency spectrum trend analysis(INPEFA)shows that the palaeoclimate and paleoenvironmental evolution of the core of Jiaoke 2 well is divided into three stages:At a depth of 556-535 m,the lake was in a low water level,the water body was in a reduction state,the type of weathering in the basin was mainly physically ventilated,and the climate was drought;in the depth of 535m-240 m,the lake had been rised,the water was increased by the reduction state to the oxidation state.Types of weathering changed from physical wind to chemical airization,the overall was in wet climatic conditions;in depth 240-8m,the weathering type of the basin was mainly physically ventilated,the water level decreases,and the climate changed to drought.An abnormal Hg deposition record was found in Well Jiaoke 2.After research,the Hg anomaly indicates the highest eruption of the Deccan igneous rock province.It reached the highest eruption point at 551.52 m.At 549.3m above the upper part of the maximum Hg anomaly,a enrichment of PAHs has been discovered.After studying the composition,source and type of PAHs,it is determined that the PAH enrichment indicates a paleo-wildfire.In combination with the results of paleoclimate reconstruction and comparison with the former studies,the K/Pg boundary was located between 549.1m-549.3m?...