【摘要】 楚雄盆地是青藏高原东缘"三江"构造带与扬子地台西缘结合部重要的含矿沉积盆地之一,以白垩纪地层赋存多个层位的砂岩型铜矿床为特征而不同于其他沉积盆地,长期备受关注。前人曾从矿床学角度进行砂岩铜矿床成矿作用相关研究,相对缺乏沉积学方面工作,进而导致对含矿岩系沉积环境及盆地属性和矿床成因认识的分歧。对楚雄盆地北部包括大村铜矿区在内的桂花地区晚白垩世含矿岩系进行了系统的地表调查、坑道及钻孔观测和沉积环境研究,认为该区上白垩统马头山组和江底河组是一套连续沉积组合,由河道亚相和边滩亚相沉积共同组成,形成于相对干旱的气候环境;沉积物源区位于盆地的北侧,曾出露有基性火山岩、花岗质岩石、碎屑岩、碳酸盐岩以及少量的变质岩等;晚白垩世时期,楚雄盆地具有北高南低的古地理格局,且在江底河组沉积成岩过程中,盆地总体曾经历了区域挤压作用引起的隆升破坏,也是区内砂岩型铜矿床的主要成矿时期。更多还原

【Abstract】 The Late Mesozoic Chuxiong Basin is located at the intersection of the western margin of the Yangtze platform and the Sanjiang orogenic belt in Yunnan province, SW China. Abundant strata-bound copper deposits and occurrences within multiple Cretaceous sandstones or mudstones have attracted considerable interest since the late 1970s. A significant amount of care was previously paid to the ore genesis of the sandstone-hosted copper deposits, but sedimentary environments and sources of their host rocks were overlooked, which seriously affects our understanding of their tectonic setting and ore-forming mechanism. Systematic geological surveying, tunnels, and drillhole logging demonstrate that the Upper Cretaceous Matoushan and Jiangdihe Formations were deposited in a braided river channel and marginal bank subfacies environment with a relatively dry climate. Detrital fragments of sandstone, conglomerate composition, and paleocurrent data demonstrate that the Chuxiong Basin developed in a southward facing paleogeography with a mixed source consisting of northern source rocks and basement uplift during the Late Cretaceous. Vast basic volcanics, granitoids, clastic rocks, carbonates, and minor metamorphic rocks should be exposed at the northern source area. The Upper Cretaceous Jiangdihe Formation also experienced the uplift and collapse events caused by syn-sedimentary compressional tectonics, and the sandstone-and mudstone-hosted copper mineralization was coeval with the growing tectonic events during the syn-sedimentation processes of the Late Cretaceous Jiangdihe Formation. This is a vital controlling factor of the major copper transport and deposition of the Guihua ore field in the Chuxiong Basin.更多还原