四川攀西地区大铜厂组与小坝组轮藻化石特征

FOSSILS FROM THE DATONGCHANG AND XIAOBA FORMATIONS IN THE PANXI AREA SICHUAN PROVINCE

本文对大铜厂组和小坝组所产轮藻化石组合特征,以及它们的时代归属进行了初步的分析与对比研究。作者指出:大铜厂组含Mesochara stipitata—M.parayranulifer—Actistochara mundula组合为代表,经鉴定共有15属41种,其时代为早白垩世晚期—中白垩世早期。小坝组的轮藻化石的属、种单一、结构亦较简单,而是以obtusochara huiliensis—O.huidongensis组合为特点,并具有浓厚的地方性色彩,其时代应为中白垩世中—晚期产物。

The Panxi area lies in the intermediate zone between the Sichuan basin and the central Yunnan basin. Cretaceous red beds are well developed. For lack of paleontological evidence, the problem of the stratigraphic division and age has not yet been solved for a long time. In rccent years abundant charophytes fossils have been found during 1:50000 regional surveys. Preliminary study shows that: the Datongchang Formation is characterized by the occurrence of the Mesochara stipitata-M. paragranulifer-Actistochara mundula assemblage, including 15 genera and 41 species, whose age is late Early to early Middle Cretaceous(late Barremian-Aptian);the charophtyes of the Xiaoba Formation are monotonus in composition and simple in structure and are characterized by the Obtusochara huiliensis-O.huicongensis assemblage, which displays a strong endemic colour. whose age is roughly middle to late Middle Cretaceous(Cenomanian-Turonian).