An analysis of ore-controlling conditions and geological features of the Wulagen sandstone-type Pb-Zn ore deposit in Xinjiang

The Wulagen lead-zinc ore deposit, located in Kashi Sag on the northwestern margin of the Tarim basin of Xinjiang, is a sandstone-type ore deposit related to the petroliferous basin. On the basis of analysis of regional strata, tectonics, sedimentary rocks and recent prospecting data, the authors studied geological features and ore-controlling conditions of the Wulagen ore deposit. It is suggested that the Paleocene Wulagen Group seems to be significant ore-bearing strata, the ore-bearing horizon is composed of a set of regressive sand, gravel, mud-carbonate sedimentary formations. The mineralization zone is developed in the contact between the second bed of first lithologic member of Wulagen Group and the dolomitic limestone (breccia). These regular tabular orebodies are consistent with the attitude of the strata. The degree of mineralization is related to the type of clastic rocks and decreases from conglomerate glutenite, pebbly-sandstone, sandstone, to mudstone.The peak of this mineralization happened in the dolomitic limestone, some of which was brecciated. It was formed by deuteric hydrothermal process. The orebody is mainly massive or small veined form. With increasing grain size, mineralization becomes stronger in other types of clastic rocks. The authors have reached the conclusion that the Wulagen ore deposit was obviously controlled by the syncline of Wulagen and the late extensional fracture structure. The major ore is mainly distributed in gravel strata and dolomitic limestone (breccia). Pyrite type lead-zinc ore was found in some part of the extensional fractures, which was developed in the contact zone between the orebody and overlying dolomitic limestone (breccia). It is also pointed out that the clastic Mesozoic-Cenozoic basin in Kashi sag on the northwestern margin of the Tarim basin is a valuable metallization prospective area for sandstone type copper-lead-zinc ore deposits.