新疆乌拉根铅锌矿沉积相古地理特征研究

Study on sedimentary facies and palaeogeographic characteristics of Wulagen lead-zinc deposit,Xinjiang

乌拉根一带中生代层控砂砾岩型铅锌矿以乌拉根大型-超大型铅锌为代表,位于塔里木盆地西部喀什坳陷的北部。区域构造环境较复杂,成矿条件优越,属乌拉根铅锌铜成矿带。本文从乌拉根铅锌矿床,依据实测剖面研究乌拉根铅锌矿内K_1kz^5辫状河三角洲各亚相及其微相的表现特征。结合前人的研究成果,从区域沉积环境、赋矿层位沉积特征与沉积相、赋矿层位古地理特征方面论述乌拉根铅锌矿的成矿机制与成矿条件,为乌拉根区铅锌找矿提供可借鉴的依据。乌拉根铅锌矿赋存于辫状河三角洲平原亚相辫状河道微相中。从赋矿岩石组合看透水的砂砾岩与上覆的石膏层,为有利的岩石组合,即辫状河三角洲平原亚相砂砾岩与上覆膏质海湾相E_1a密闭性石膏。

Pb-Zn deposits in Wulagen area are generally represented by Wulagen Pb-Zn deposit, which is stratabounded type and super-large in reserves. The study area is located in the north of Kashgar depression, the west of Tarim basin and former′s studies indicated that Wulagen Pb-Zn deposit typically occurred in the Wulagen Pb-ZnCu metallogenic belt, which is the most important metallogenic belt in northwest margin of Tarim Basin. This work systematically studied the typical ore deposits of Wulagen, Dake and kashgar, and analyzed the sedimentary characteristics of outcrop section in the studied area. The regional sedimentary environment, sedimentary facies and characteristics of ore-bearing layers were examined combined with summarization of former research results. Finally, the metallogenic factors and mechanism of sandstone-conglomerate type of strata-bound Pb-Zn deposits are discussed to aim at providing a reference basis for explorations of Pb-Zn deposit in the study area.The results show that Wulagen Pb-Zn deposit developed in braided channel micro-facies. Permeable sandstone-conglomerate and the overlying gypsum layer are favorable lithological combinations. The gypsum layer acted as seals for the ore deposits.