关岭生物群和卡尼期早期裂谷

讨论晚三叠世卡尼期早期关岭生物群的生存环境和死亡埋葬特点,认为该生物群分布于裂谷地区;生物群的群体死亡并被迅速埋葬的原因是地震;贵州龙生物群与关岭生物群是同期生物群;"S形带"是一构造断陷带,在卡尼期早期是裂谷。

ON THE GUANLING FAUNA AND ITS SIGNIFICANCE

This paper discusses the geological contexts of the Guanling fauna,which occurs in the lower Carnian(Upper Triassic) Wayao Formation(=Xiaowa Formation) in the Guanling area of Guizhou Province,southwestern China,and contains a large number of exceptionally preserved marine fossils,including marine reptiles,crinoids,ammonoids,bivalves,brachiopods,and conodonts.The conclusions are as follows.1) The lithological and faunal characters,especially taphonimic features,indicate that the Guanling fauna most likely lived in a rift valley environment.The mass mortality of the fauna may have been caused by a seismic disaster according to Wang Shang-yan(2006).2) The Kueichousaurus hui fauna,which is characterized marine reptiles and associated fishes,ammonoids,bivalves,and conodonts,from the lower Carnian in Xingyi-Anlong-Luoping districts,is herein correlated with the Guanling fauna based on conodonts,ammonoids and the Halobia-assemblage.3) The spatial distribution of the Guanling fauna and the Kueichousaurus hui fauna follow a "S-shaped zone",which is interpreted as a tectonic belt situated between the Yangtze Platform and the Napanjiang Basin in the Triassic Period.This "S-shaped zone" was a fault-bounded depression in the Middle Triassic,became a rift valley in the early Carnian,and turned into a bay during the late Carnian-early Norian ages.