Distribution and controlling factors of reefs and oolitic beaches for the Changxing to Feixianguan formations in the northern Sichuan basin

Abstract：This paper relatively intensively discusses the characteristics, distribution and controlling factors of reefs of the Changxing Formation and beaches of the Feixianguan Formation in the northern Sichuan basin. It is thought that: the reefs are transgressive reefs formed during the regional sea-level rise and vertically mainly distributed in the middle and upper parts of the Changxing Formation, and the oolitic beaches mare mainly regression beaches developed in the process of regional sea-level fall and vertically distributed in Members 1 to 3 of the Feixianguan Formation. In a plan view, reefs and beaches mainly occur in zones on both sides of the Guangyuan-Liangping sea trough. In the period of Changxing, with the rise of sea level reefs moved in the direction of transgression and their horizon was gradually uplifted; in the Feixianguan period, with the fall of sea level the beaches migrated toward the trough and their horizon had a trend of gradual rise. The main factors that controlled the formation and development reefs and beaches of the strata are sea-level fluctuation, tectonics, contemporaneous faults and paleoclimate.