新疆乌拉根砂岩型铅锌矿床地质特征与控矿条件

新疆乌拉根铅锌矿是与含油气盆地有关的砂岩型矿床,发育于塔里木盆地西北缘的喀什凹陷。在区域地层、构造、沉积岩和最新勘探资料综合分析的基础上,对该矿床的地质特征和控矿地质条件进行了研究。结果表明,其矿化层为一套海退砂、砾-泥-碳酸盐岩沉积建造,下白垩统克孜勒苏群(K1kz)和古新统阿尔塔什组(E1a)是成矿的物质基础,矿化蚀变发育于下白垩统克孜勒苏群第五岩性段+古近系阿尔塔什组第一岩性段,铅锌矿体呈层状、似层状产出,总体产状与地层产状一致。碎屑岩与矿化关系显示,从砾岩-砂砾岩-含砾砂岩-砂岩-泥岩,矿化强度依次减弱,除白云质(角砾)灰岩由于后期热液叠加多形成块状、细脉状矿石,矿化最强外,其余岩性按岩石颗粒粒度从小到大,矿化强度依次增强。该矿床的形成明显受乌拉根向斜和后期张性裂隙构造的制约,主矿体主要分布在砂砾岩层和白云质(角砾)灰岩中,矿体和上盘白云质(角砾)灰岩接触带局部张裂隙中发育黄铁矿型铅锌矿。塔西南喀什凹陷北缘中新生代碎屑岩盆地,是寻找砂岩型铜铅锌等多金属矿床最有利的远景区带。

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.