豫西陕县放牛山组的建立

THE ESTABLISHMENT OF THE FANGNIUSHAN FORMATION AT SHANXIAN,WESTERN HENAN

豫西陕县一带，有一套中浅变质碎屑岩──碳酸盐岩系。前人将其归于太古界太华群或早元古代熊耳群。笔者通过地层清理发现，该套地层下与太华群、上与熊耳群均呈不整合关系，为一独立的岩石地层单位。因其发育在放牛山地区，故建立新的岩石地层单位──放牛山组。本文对放牛山组层型剖面进行了描述。

In the vicinity of Shanxian ,western Henan,there occurs a sequence of medium-to low-grade metamorphicclastic rocks and carbonate rocks, which was assigned by predecessors to the Archean Taihua Group or Early Pro-terozoic Xiong’er Group. Through sorting stratigraphic units,the author found that this sequence is an independentlithostratigraphic unit,lying unconformably on the Taihua Group and below the Xiong’er Group. As it occurs in theMount Fangniu area,a new lithostratigraphic unit named the Fangniushan Formation is established.This paper de-scribes the stratotype section of this formation.