滇东南泸西县上三叠统卡尼阶小凹组菊石

本文对云南省东南部的泸西县白水镇小兴安村上三叠统卡尼阶小凹组菊石类进行了详细研究,共发现菊石9属13种,其中Anasirenites属为华南首次发现。依据各物种组合特征及其地层分布情况,自下而上识别出菊石Trachyceras multituberculatum带和Austrotrachyceras triadicum带,时代对应于晚三叠世早卡尼期的Julian 1和Julian 2。该菊石组合不仅记录了卡尼期Julian期Trachyceratidae的辐射事件,同时该菊石组合与卡尼期特提斯域和泛大洋域的菊石组合均有良好的对比性,并且为华南古地理研究提供了新的补充材料。另外,通过对剖面的岩性特征与菊石生物地层特征分析,认为在滇东南地区由于卡尼期湿润幕事件(CPE)所导致的碳酸盐岩台地消亡起始时间应为Julian 1末期略早于陆源碎屑输入的Julian 2亚期。

Ammonites from the Carnian (Upper Triassic) Xiaowa Formation, southeast Yunnan Province

This paper describes a new ammonoid assemblage from Luxi County, southeastern Yunnan Province. The assemblage comprise of 13 species of nine genera of ammonoids of which Anasirenites is discovered for the first time in South China. The Trachyceras multituberculatum zone and the Austrotrachyceras triadicum zone are recognized from the bottom to the top based upon the characteristics of each species of the assemblage and their stratigraphic distribution. The date corresponds to Julian 1 and Julian 2 of the early Carnian (Late Triassic). The ammonoid assemblage not only records the radiative events of the Trachyceratidae in the Julian of the Carnian, but also provides a good correlation with the ammonoid assemblages in the Tethys and Panoceanic of the Carnian and new supplementary materials for the study of the palaeogeography of South China. In addition, based on analysis of lithologic and biostratigraphic characteristics of the ammonoids, it is concluded that the disappearance of the carbonate platform caused by the Carnian Pluvial Episode (CPE) in southeastern Yunnan started at the end of Julian 1, slightly earlier than the terrigenous clastic inputs in Julian 2.