Qinghai Xitiesan Pb-zn Deposit Mineralization Basin Characteristics And Tectonic Deformation

Xitieshan lead-zinc ore deposit is SEDEX type deposit, a large lead-zinc ore deposits which located in the early Palaeozic rift in the north region of Chaidamu basin. The deposit is deformed by strong tectonics in Jialidong movement. The author study the ore control basin structure characteristic in the course of deposit form and reform characteristic in proceed tectonic movement, summary the ore control structural pattern and metallization regulation of the deposit.The paper detailed introduces the orebody shape feature in map view, cross section and lateral section, and statistics analyze the orebody thickness. Basing on the domestic and international research of uplift-monocline basin and stratigraphic sequence of ore-hosted sedimentary strata, recover the shape and occurrence of basin which control deposit, discover that Xitieshan metallization basin owns to normal-drag uplift-monocline basin which control the 3D feature of ore layer. According to statistics analysis results of mineralization element data of the deposit, further find out that mineralization distribution inner orebody is consistent to the shape of deposit controlled by basin structure. According to the shape of deposit, the metallization mode is sediment-fan, which perfect the ore control basin structure.By studying deformation structure of ore body, the en echelon ore body has two types, front step and rear step. Above ore body mostly array front step, some array rear step, below ore body all array rear step. Basing on the deformation mechanism of fold, which the shear direction is consistent in the same limb, the ore body located in the limb of fold has the same rear step. Field observations show it has discordance contact between Dakendaban group and Tanjianshan group strata. The shear type and strata relation prove the tectonic pattern of deposit is downfold. Ramp fault explained ore body array front step and both of inverted limbs, revealed the whole deposit deformation process, further provided the new proof for metallization prognosis.