北山区主要指甘肃西部的马鬃山区,向西延入新疆,北与蒙古人民共和国相邻,向东跨入巴丹吉林沙漠。巴丹吉林南部阿拉善地区在甘肃区域地层表的综合地层区划中是划归华北区的,但该区石炭、二叠纪在沉积或岩浆岩方面却表现了强烈的活动性。所以应归入天山——兴安地槽系。 Beishan mainly refers to Mazong Mountain in the west of Gansu, extending westward to Xinjiang and adjacent to the People’s Republic of China to the north in the north, entering the Badain Jaran Desert to the east. The Alxa area in southern Badan, Jilin, was subdivided into North China in the comprehensive stratigraphic division of the Gansu regional stratigraphic table, but the Carboniferous and Permian areas show strong activity in sedimentary or magmatic rocks. Therefore, should be classified in Tianshan - Xingan trench system.