Lithology and Distribution Characteristics of the Oolitic Beach from the Feixianguan Formation, Eastern Sichuan Basin.

[Objective] To solve the problems such as unclear lithological variations of the Feixianguan Formation on the western side of the marine trough's southern segment and within the plateau interior of the eastern part of the Sichuan Basin, [Methods] the lithological types and characteristics of the Feixianguan Formation were studied by comprehensively using multiple geological data such as cores, drilling and logging, and an intelligent identification method of lithological logging based on machine learning was proposed, which solved the technical problems of fine identification of lithology in the old area, and revealed the lithology, distribution and evolution of the Feixianguan Formation in the area. [Results and Conclusions] (1) The Feixianguan Formation is mainly composed of lithology such as mudstone, mud crystal limestone, argillary limestone, granule limestone, granulous dolomite, mud crystal dolomite, paste dolomite, and gypsum rock; (2) Comparison found that the improved gradient-boosted decision tree algorithm, namely Stochastic Gradient Boosting Decision Tree (SGBDT), is superior to other algorithms for constructing lithology models, and is more suitable for carbonate rock complex lithology identification; (3) The granule limestone developed intensively in the area south of the Kaijiang-Liangping Sea Trough between Feixianguan I period and Feixianguan III period, and the granulous dolomite was concentrated in the Feixianguan II period and distributed and scattered; (4) The distribution of the oolitic shoal in the area exhibits significant variation. The main development of the plateau ancient geomorphological high point and the edge of the platform in the Feixianguan I period. In the Feixianguan II period, most of the the oolitic shoal at the edge of the platform were developed, and a small number of ancient landforms in the platform were developed .And the main development of the plateau ancient geomorphological high point in the Feixianguan III period. [ABSTRACT FROM AUTHOR]