扬子地块西南缘大面积低温成矿时代  

Epoch of large-scale low-temperature mineralizations in southwestern Yangtze massif

作　　者：胡瑞忠[1] 彭建堂[1] 马东升[2] 苏文超[1] 施春华[1] 毕献武[1] 涂光炽[1] 

机构地区：[1]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550002 [2]南京大学地球科学系,江苏南京210093

出　　处：《矿床地质》2007年第6期583-596,共14页Mineral Deposits

基　　金：国家973项目(G1999043200;2007CB411408);国家自然科学基金项目(40472053;40634020)资助

摘　　要：中国西南地区(川、滇、黔、桂、湘)发育有世界上很典型的低温成矿域,其面积之大(约90万km2)、包含的矿种之多(Au、Hg、Sb、As、P、Pb-Zn、U、Ni-Mo-PGE、重晶石、冰州石和分散元素等)、矿床组成和组合之复杂,在全球十分鲜见。扬子地块西南缘是中国西南大面积低温成矿域的重要组成部分。近年来,作者采用Rb-Sr、Sm-Nd、Ar-Ar等多种同位素定年方法,对扬子地块西南缘产出的磷矿、金矿、锑矿等低温矿床的成矿时代进行了较系统的研究。文章总结了这些研究成果,并结合前人的资料,初步拟定出该区存在三期大规模低温成矿作用,它们分别相当于晚元古代—早古生代(晚震旦世—早寒武世)、晚加里东期(晚志留世—早泥盆地)和燕山期(晚侏罗世—中白垩世)。该区的磷矿、重晶石矿和黑色页岩中的镍钼铂矿主要形成于晚元古代—早古生代,同位素年龄主要为585～540Ma;赋存于前寒武纪浅变质碎屑岩中的金-锑-钨矿床主要形成于晚加里东期,同位素年龄主要为435～380Ma;产于寒武系以后地层中的锑矿床主要是在中燕山期成矿,同位素年龄主要为160～140Ma;而该区的卡林型金矿和汞矿主要在燕山中晚期大规模成矿,同位素年龄主要为170～80Ma。There exists a typical low-temperature metallogenic domain in southwestern China, which covers Sichuan, Yunnan, Guizhou, Guangxi and Hunan. As a unique region in the world, this domain is characterized by its large area （about 900 000 km^2）, many kinds of mineralization （Au, Hg, Sb, As, P, Pb-Zn, U, Ni-Mo-PGE, barite, calcspar, and dispersed elements）, and complicated compositions and associations of ore deposits. The southwestern Yangtze massif is an important part of the low-temperature metallogenic domain in southwestern China. In recent years, the authors have systematically studied the metallogenic epochs of P, Au, Sb low-temperature mineralizations in southwestern Yangtze massif by using Rb-Sr, Sm-Nd, and Ar-Ar isotopic geochronolgical dating methods. With the combination of previous data, this paper has summarized the dating results and pointed out that there exist roughly 3 stages of large-scale low temperature mineralization, which are equivalent to Late Proterozoic-Early Palaeozoic （Late Sinian-Early Cambrian）, Late Caledonian （Late Silurian-Early Devonian） and Yanshanian （Late Jurassic-Middle Cretaceous）. The phosphorite deposits, barite deposits and Ni-Mo-PGE deposits in the area were formed mainly in Late Proterozoic-Early Palaeozoic, with isotopic ages mainly ranging from 585 Ma to 540 Ma. The Au-Sb-W deposits hosted in the Precambrian low metamorphic clastic rocks were mainly formed in Late Caledonian, with isotopic ages mainly ranging from 435 Ma to 380 Ma. The Sb deposits hosted in post-Cambrian strata were mainly formed in Middle Yanshanian, with isotopic ages mainly ranging from 160 Ma to 140 Ma. The Carlin-type gold mineralization and the Hg mineralization in the area were mainly formed in Middle and Late Yanshanain period, with isotopic ages ranging from 170 Ma to 80 Ma.

关 键 词：地质学 扬子地块西南缘 低温成矿作用 成矿时代 晚元古代-早古生代 晚加里东期 燕山期 

分 类 号：P617[天文地球—矿床学] P597[天文地球—地质学]