四川天全、芦山、宝兴地区名山组地层特征

下第三系名山组广泛分布于天全-芦山复向斜内,地层出露良好。笔者(1989—1991年)在参加1:5万天全幅、灵关幅区域地质调查时,根据岩组图填图要求,又进一步展开了对名山组的研究。本文简要地介绍了新实测的地层剖面,以及重新将名山组划分为4个段和新建大溪砾岩等填图单元的情况;并阐述了将芦山组归并于名山组上部(4段)而取消该组名称的依据。综述了研究区的岩石组合特征、沉积构造,建立了地层层序。将名山组沉积环境解释为辫状河及湖泊环境。

STRATIGRAPHY OF THE MTNGSHAN FORMATION IN TIANQUAN-LUSHAN-LINGGUAN, BAOXTNG

Mingshan Formation of the Neocene is widely and well exposed in the Tianquan -Lushan synclinorium. Engaging in the regional geological reconnaissance in the Tianquan and Lingguan maps of 1:50000, in 1989-1991, according to the demand of geological mapping with rock assemblages, the whriter made a further researth on the stratigraphy of the Mingshan Formation. This paper has presented a mewly surveyed stratigraphic profile, and newly has divided the Mingshan Formation into 4 Members, and has established a Daxi Conglomerate unit. The orginal Lushan Formation has been put under the Member 4 of the Minngshan Formation. The rock assemblages, sedimentary structures have been deseribed, the stratigraphical succession has been established. The sedimentary environment of the Mingshan Formation has been interpreted as braided stream and lakeshore.