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白银地区火山岩分布广泛,发育较好,而与其它变质岩系界线甚不明显,关系不清,加之,过去未采到化石,所以对其时代各说纷云。最早把青海门源以东包括甘肃天祝、白银和青海大通地区的寒武、奥陶、志留、泥盆纪地层笼统称为“南山系”。后在“南山系”的上部层位一祁连山西部东大窑附近的砂岩层中采到志留纪化石,在“古浪灰岩”中采到腕足类、头足类化石,鉴定为奥陶纪产物。分布在白银厂及其周围地区的火山岩,1958年以前在该区的地质工作者,都把它定为志
The volcanic rocks in the silver area are widely distributed and well developed, while the boundaries with other metamorphic rocks are not obvious and their relationship is unclear. In addition, in the past, fossils were not collected in the past, so they all talked about their times. The earliest of the Cambrian, Ordovician, Silurian and Devonian strata, including Tianzhu of Gansu Province, Baiyin and Datong of Qinghai Province, are the earliest known as the “Nanshan line” to the east of Qinghai Menyuan. Later, the Silurian fossils were collected in the sandstone layer near the Dongda kiln in the western part of the Qilian Mountains in the upper layer of “Nanshan System”, and the brachiopods and cephalopods were collected in the “Gulang limestone” Ji product. The volcanic rocks distributed in and around the Baiyin Plant were identified as geologists in the area before 1958