内蒙古二连盆地古近系研究回顾及存在问题

简要回顾了内蒙古二连盆地古近系研究的历史,介绍了最新的研究进展,同时对主要地点的位置以及地层发育情况进行了讨论,并针对不同地点或地区分析了二连盆地古近系划分对比中存在的问题,对化石产地的地名和岩石地层单位名称的使用提出了建议。

COMMENTS ON PALEOGENE LOCALITIES AND STRATIGRAPHYIN THE ERLIAN BASIN,NEI MONGOL,CHINA

The Erlian Basin is located in central Nei Mongol(Inner Mongolia),near the China-Mongolia border.Its coordinates are approximately 42°-44°N and 110°-114°E(Jiang,1983). The Paleogene strata in the basin are well-exposed and fossiliferous.Since the 1920s,the Central Asiatic Expeditions of the American Museum of Natural History(CAE),the Sino-Soviet Paleontological Expedition,the Regional Geological Survey of Nei Mongol Autonomous Region, and the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences(in collaboration with the American Museum of Natural History and the Carnegie Museum of Natural History in recent years) have investigated the Erlian Basin.Such work has established a stratigraphic framework and provided the basis for a number of proposed lithostratigraphic unit names.Several faunas from the Erlian Basin have been the base of Asian Paleogene Land Mammal Ages that have been widely accepted(Luterbacher et al.,2004).The Erlian Basin has thus become an important area for the study of Asian Paleogene mammals,stratigraphy and related issues.For a long time,however,some confusion has existed regarding the usage of locality names,and clarity has been lacking with respect to the definitions,subdivisions and correlative relationships of some lithostratigraphic units in the region.In the course of his study of Asian Paleogene tapiroids,Radinsky(1964) discussed the Eocene and Oligocene fossil localities in the Erlian Basin and questioned the stratigraphic assignments of some localities,but he failed to clarify the local stratigraphy.The purpose of this paper is to clarify some of the uncertainties that exist regarding both locality names and stratigraphy,based on our recent investigations and on comparisons of our new data with previous references and the CAE archives. Because the definitions of some formations vary among localities or areas,the following discussion of locality names,and the stratigraphic subdivisions and correlations is organized geographically in order to avoid further confusion(refer to Fig.1 for the localities).