Stratigraphic Features and Belongingness of Sandstone Type Copper-Deposit in Yumen-Sunan Area of Gansu

Yumen-Sunan is a metallogenic province of marine sand stone-type copper deposit in the west section of northern Qilian area.During Early Paleozoic era,the strata in this area were mainly the marine volcanic-sedimentary formation in the Six copper deposits(spots) of Tianlu,Gangou-Laohugou,Maoniugou,Tianqiaowan,Sanzhiyang,and Hongkouzi,all in the upper part of lower Paleozoic strata.The belongingness of their age remains controversial.Through further study of stratigraphic features of measured section of Tianlu copper deposit,the,author think that the rock composition,stratigraphic sequence,and geochemistry of ore-containing strata of sand stone type copper deposit in this area are distinctly different from that of the upper stratigraphy of late Silurian Epoch.According to regional comparison,the ore-containing strata of sand-stone type copper deposit of the area are the upper member of Quannaogoushan Formaition,belonging to the middle Silurian.