STUDY ON THE PALEOMAGNETISM OF THE XIGEDA FORMATION
Qian Fang Xu Shujin (Institute of Geomechanics Chinese Academy of Geology)Chen Fubin Zhao Yongtao (Chengdu Institute of Geography, Academia Sinica)
The results of magnetism measurements of the Xigeda Formation whit four sections in Southwest Sichuan show that the greater part of the Xigeda Formation is positive polarity which corresponds to the Couss, Polarity Epoch in the Late Cenozoic Era Polarity Timescale, There are two events of polarity reversal in it, which correspond to the Mammoth Event and the Kaena Event in the Couss. The upper part of the Formation is negative polarity which corresponds to the lower part of the Maturama Polarity Epoch. There are also two events of polarity revesal in it, which can correspond to the Reunion Event and the Olduval Event in the Maturama. The period during which the la -yer was formed from 3.286 million to 1.782 million years BP.The polarity series of the Xigeda Formation can correspond to the Number Ⅰ and Number Ⅱ of the Yuanmou Formation in Yunnun. It also corresponds to the Number Ⅱ and the lower part of the Number Ⅲ of the Yushe Formation in Shanxi. The information of the stratigraphic correlation and the paleontological correlation are in agreement with the results mentioned above. The age of the Xigeda Formation belongs to the Early Pleistocene Epoch.