湖北大冶沙田下三叠统菊石、双壳动物群的发现及其地层意义

THE DISCOVERY OF AMMONOID AND BIVALVE FAUNAS OF THE LOWER TRIASSIC AND THEIR STRATIGRAPHIC SIGNIFICANCE IN SHATIAN, DA YE COUNTY,HUBEI PROVINCE

本文所研究的湖北大冶沙田下三叠统菊石、双壳动物群,包括菊石10属11种,双壳类4属9种。文中建立了5个菊石带:Lytophiceras带、Gyronites带、Flemingites带、Pseudosagece-ras—Xenodiscoides带和Anasibirites带;2个双壳动物带:Claraia griesbachi带和Cl.concentrica带,并依据动物群面貌,将原大冶群的时代详细划分为大冶组和观音山组。大冶组的时代相当于格里斯巴赫期至亭纳尔期,观音山组的时代相当于斯密斯期至斯派斯期。

The Lower Triassic ammonoids and bivalves dealt with in this paper are collected from Shatian, Daye County, Hubei Province. The ammonoids studied include 11 species of 10 genera and the bivalves 9 species of 4 genera. Five ammonoid zones (Lytophiceras zone, Gyronites zone, Flemingites zone, Pseudosageceras - Xenodiscoides zone and Anasibirites zone) and two bivalve zones (Claraia griesbachi zone and Cl. concentrica zone) were recognized. According to the lithological and faunal features, the Lower Triassic of this area, i. e. Daye Group is divided into Daye Formation and Guanyinshan Formation. The age of the Daye Formation is considered from Griesbachian to Dienerian, and the age of the Guan yinshan Formation is considered from Smithian to Spathian.