川西冕宁—泸沽地区早更新世双桥冰期之证据

THE EVIDENCES OF THE SHUANGQIAO GLACIATION OF THE EARLY PLEISTONCENE, MIANNING-LUGU AREA, WEST SICHUAN PROVINCE

川西冕宁—泸沽地区晚新生代地层分为15层。其中包括7级阶地。除早更新世双桥组为冰碛外,其它均为非冰川沉积。作者对1872高地上双桥组下砾石层的物质来源、相关地貌、沉积构造、砾石圆度、基质粒度特征及石英砂表面结构进行了综合研究,确认该砾石层为冰碛。据此,建立了早更新世中、早期双桥冰期。

This paper subdivides the Late Cenozoic stratigraphy of the studied area into fifteen formations, including seven terraces. Except for the Shuangqiao Formation which belongs to a till,the others all are nonglacial sediments. We have made a sys-tematic study of the lower gravel bed of the Shuangqiao Formation on the upland which is 1872 meters high in respect of boulder sourceland,relevant geomorphology, sedimentary structure, roundness, matrix size characteristic, and surface texture of quartz sand. Finally, the gravel bed was confirmed to be a till. In view of the above mentioned, we have established the Shuangqiao glaciation of the middle -early stage of the Early Pleistoncene.