江汉平原下更新统

LOWER PLEISTOCENE SERIES IN JIANGHAN PLAIN

作者在江汉平原第四纪地质系统工作的基础上,首次建立了位于平原边缘地带的下更新统“卢演冲组”和“阳逻组”。卢演冲组和阳逻组分布另星,组成长江在本区内的第Ⅴ级或第Ⅳ级阶地。根据其岩性特征、地貌表现、成因组合、生物组合、成岩程度和构造关系,可以和新第三纪“拾回桥组”和“掇刀石组”区分,也能从广泛分布在湖北省内的多层砾石层中加以辨别。为恢复江汉平原早更新世古地理、尤其是长江的发育史以及解决第四纪下限提供了重要依据。

Based on the systematic researches of Quaternary geology in Jianghan plain, the authors have reestablished the Quaternary stratigraphic time-scale of this area, and first established and discussed the Lower Pleistocene-Luyanchong Formation and Yangluo Formation in detail. The two Formations scattered over this area and constituted the V-stepped or IV-stepped terraces of the Yangtze River. Based on the lithological characteristics, morphological display, genetic sequence, diagenetic degree, paleontogic facies and structural relations, the two Formations may be distinguished from the Neogene system-Shihuiqiao Formation, and also do from the widely spread gravel beds. The above-mentioned might help to recover the Early Pleistocene's palaecgeographic character, especially the evolutional history of the Yangtze Rivetr and solve the problem of the lower boundary of the Quaternary.