蜀南地区下三叠统飞仙关组沉积相

蜀南地区飞仙关组的沉积相类型主要有浑水陆棚相与清水陆棚相,东部两者交替发育,中西部则主要为浑水陆棚相。浑水陆棚相以半局限海亚相为主,包括三个微相;清水陆棚相可分为颗粒滩、滩间、潮坪和内缘斜坡等四个亚相,包括若干微相。飞一段全区为清水陆棚相;飞二段全区均为浑水陆棚亚相的泥质半局限海微相;飞三段,西部为浑水陆棚相,东部为清水陆棚相,其间发育灰泥质半局限海微相;飞四段基本为泥质半局限海微相。飞一时,区内中部有一近南北向的台内凹槽,沿凹槽边缘鲕粒滩较发育。研究区以西的康滇古陆和龙门山岛链与华蓥山断裂带控制着区内沉积相展布,当康滇古陆和龙门山岛链构造活跃时全区发育浑水陆棚,华蓥山断裂带活动时东部发育清水陆棚;当康滇古陆、龙门山岛链与华蓥山断裂带构造的活动性都较低时,全区以清水陆棚为主。

Lower Triassic Feixianguan Sedimentary Facies in South Part of Sichuan Basin

The researched sedimentary area is in a group of echelon low anticlines which extend southwestwards from Huayingshan Faulted Belt. It was a depression area during Caledonian period, a part of paleouplift during Indosinian period and an uplift area since Mesozoic era. Huayingshan Faulted Belt was not only dominate distribution of the structures but also affect evolvement of the sedimentary facies. Troubled water and clean water shelf facies developed alternatively in the east of Lower Triassic Feixianguan Formation sedimentary area but troubled water shelf facies was mainly in the center and west parts of it. The development and distribution of different sedimentary facies are described in this area. It is shown that the distribution of the sedimentary facies was controlled by the Western Kangdian Ancient Land, Longmenshan Island Chain and the Eastern Huayingshan Fracture Belt. The troubled water shelf facies developed when the Kangdian Ancient Land, Longmenshan Island Chain's construction was active, and the clean water shelf facies developed when the Eastern Huayingshan Faulted Belt was active,and the clean water shelf facies mainly developed when all of them were relatively quiet.