论额尔登敖包下第三系——兼论湖牧兽在该地之发现

A PALEOGENE SECTION AT ERDEN OBO, NEI MONGOL AND ON THE DISCOVERY OF PASTORALODON LACUSTRIS (PANTODONTA, MAMMALIA) IN THAT AREA

内蒙古沙拉木伦地区额尔登敖包下第三系剖面为亚洲下第三系最佳剖面之一。但过去的地层研究过于简单,有关地层层位的时代不准确,因此,对其进行全面的认识实有必要。湖牧兽(Pastoralodon lacustris)仅发现于脑木根组,而从未在其它下第三系层位中发现过。因而,在额尔登敖包地区发现的湖牧兽表明这一地区并不存在中始新世阿山头组,而早始新世巴彦乌兰层的存在则是确凿无疑的。

Paleogene section of Erden Obo (Urtyn Obo) is one of the best known Paleogene sections in Asia. But the understanding of it was insufficient and simplified in the division of strata and in the demarcation of the boundaries. This paper attempts at a revision of the former.