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近二十年来,随着我国地质事业的蓬勃发展,加强了北山地区的工作,其地质研究程度速迅提高,地层的研究工作亦有新的进展,早志留世笔石相地层的发现就是其中的一项新成果。北山的早志留世笔石相地层是甘肃省地质局区调队1966年于甘肃省肃北县罗雅楚山最先发现的,并命名为黑尖山组。1974—1980年,甘肃省地质局地质力学区测队相继在中蒙边界黑鹰山地区进行1:20万区调工作,于黑鹰山—居延海一带的圆包山及小狐狸山两地先后发现含笔石的早志留世地层,由于该地岩性和黑尖山组岩性有明显差异,而且笔石化石丰富,故另起新名为圆包山组(图1)。
In the recent two decades, with the vigorous development of geological undertakings in our country, the work in Beishan area has been intensified. The degree of geological research has been rapidly increased and new progress has been made in the research of stratigraphy. A new achievement. Beishan Prehistoric pen-gravel stratum was first discovered by Gansu Provincial Geological Bureau Regulating Team in 1966 in Luo Ya Chushan, Subei County, Gansu Province, and named as Black Jianshan Formation. From 1974 to 1980, the Geological Mechanics Zone of Gansu Bureau of Geology mechanized team successively in the Sino-Mongolian border area of Black Hawk mountain 1: 200000 regional transfer work, in the Black Hawk Mountain - Juyanhai area roundabout and Little Fox Mountain two In the area, the Early Silurian strata have been discovered. Since the lithology of the Early Silurian and that of the Black Jianshan Formation are obviously different, and the petroglyphs are rich, they are newly named as the Yuanbaoshan Group (Figure 1).