关岭生物群和卡尼期早期裂谷

ON THE GUANLING FAUNA AND ITS SIGNIFICANCE

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。

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 fol- lows. 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 cono- donts, 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.