关于下蜀组沉积初期自然环境面貌的初步推断

下蜀组在长江下游分布很广,与农副业生产关系密切,是许多大型工程建筑的地基持力层。虽然几十年来许多地层古生物学工作者做了大量的研究,使之成为晚新生界的典型层位,但对其成因和代表的环境等尚存在分歧看法。本文讨论一例五十年代可能发现于下蜀组底部的、近年来生境研究得十分清楚的生物化石,认为下蜀组沉积初期的环境可能是温湿、低平、多水域的,沉积成因类型可能是水成的。在生物证据不多的情况下,哪怕增加一点点说明问题的生物线索都显得异常珍贵,因为往往生物反映的环境面貌比较地全面和具体。

A PRELIMINART INFERENCE ON THE NATURAL ENVIRONMENT OF EARLY XIASHU EPOCH

In 1955, an Elaphurus davidianus fossil specimen was discovered in the stratum of Early Xiashu Epoch by Prof. Yang Zhongjian. On the basis of Prof. Yang's discovery and the knowledge of the species' palaeo-ecology, the writer puts forward the preliminary inference on tne natural environment as follows: (1) The inference on the natural environment of Early Xiashu Epoch will be reliable if the locality and stratum reported by Prof. Yang Zhongjian is reliable; (2) The natural environment of Early Xiashu Epoch should show a landscape of a warm and moist plain with some marshlands and bodies of water. It should belong to the typical environment of the Oriental Realm Probably, its latitudes roughly correspond to Zhejiang, Shanghai or the delta plain of Yangtze, even to the south of the areas; (3) Very likely, the stratum of Early Xiashu Epoch was brought into being by aqueous buildup.