Effect Of Intrusive Rocks On The Evolution Of Organic Matter And Geochemical Characteristics Of Surrounding Rocks In Linnan Sag

Linnan sag located in the southwest of Huimin sag, which is affected by the Cenozoic fault-depression with intense magmatic activity and developed a large number of intrusions. This paper takes Xia 38 block intrusion in Linnan depression as the object of study. The petrological and geochemical characteristics of intruder are clarified. The influence and reason of intrusion working on surrounding strata are analyzed, and the affected area of surrounding rock is elucidated.By field core observation, thin slice microscopic identification and analysis of the main trace elements of the rock and conclude that the lithology of the Xia 38 block intrusion is mainly diabase with a small amount of basalt and the magma is alkaline and has the characteristics of potassium and sodium. The analysis of trace elements found in magmatism belonging to intraplate rift type basalts. The analysis of rare earth elements shows that the magma source area has a relatively high degree of melting from the deeper mantle source without obvious differentiation in the formation process.Through the analysis of the organic carbon content and vitrinite reflectance of the surrounding rock, it is determined that the evolution of organic matter was promoted by the intrusive rocks, which results in the decrease of the content and the increase of maturity of organic matter. Based on the observation of field core,identification of rock slice, quantitative analysis of clay minerals and determination of isotope, it is found that the effect of hot bake also makes the surrounding rock brittle and the fracture develops later. The intrusive rock caused the abnormal conversion of clay minerals in the surrounding rock and promoted the formation of carbonate cements. Under the influence of intrusive rock, the 87Sr/86Sr of the surrounding rocks decreased obviously.According to the law of heat conduction of the surrounding rock, the paper established the thermal model of three kinds of intrusive rock. The paper confirmed the distribution of the temperature field around the intrusive rock and the Influence scope of the thermal effect of the intrusive body on the surrounding rock. Using the measured vitrinite reflectance data to restore the highest paleo temperature of the surrounding rock, it is verified that the thermal conduction model of the Xia 38 intrusive body is dominated by simple heat conduction in the thermal model of the three intrusive rocks.