阿尔泰造山带南缘和准噶尔板块北缘晚古生代构造演化及多金属成矿作用

Late Paleozoic tectonic evolution and polymetallic ore-forming processes in southern Altay and northern Junggar

研究表明,阿尔泰南缘和准噶尔北缘晚古生代大地构造演化及成矿作用均受古亚洲洋形成与演化的控制。晚古生代该地区经历了3个不同性质的构造演化阶段,同时伴有不同的多金属成矿作用。早泥盆世,由于古亚洲洋板块的俯冲,在阿尔泰南缘形成了一系列陆缘断陷盆地,并伴随以铅、锌、铜、铁多金属为主的矿化;同时,俯冲的古亚洲洋板块发生部分熔融,形成了埃达克岩及与其有关的铜矿床。随着板块俯冲的继续,中泥盆世出现了前弧盆地,并形成了铜-铅-锌多金属矿床。至石炭纪,西伯利亚板块与哈萨克斯坦-准噶尔板块发生碰撞,在额尔齐斯缝合带附近出现了由于挤压作用而形成的金矿床,同时,在缝合带北侧(阿尔泰地区),由于壳型花岗岩的广泛发育,形成了稀有金属矿床。早二叠世,在额尔齐斯缝合带附近又发生了碰撞后的板内拉张作用,从而诱发了一系列与地幔作用有关的岩浆活动,形成了以喀拉通克为代表的铜-镍矿化。因此,阿尔泰南缘和准噶尔北缘晚古生代多金属找矿远景区包括:阿勒泰南缘早泥盆世火山-沉积盆地内铅、锌、铜及铁多金属矿床和准噶尔北缘早泥盆世与埃达克岩有关的铜矿床;中泥盆世前弧盆地内的铜多金属矿床;石炭纪额尔齐斯缝合带内与碰撞有关的金矿床及稀有金属矿床;早二叠世与板内拉张有关的铜-镍多金属矿床。

Studies show that Late Paleozoic tectonic evolution and metallogenesis of southern Altay and northern Junggar are mainly controlled by the formation and evolution of the Paleo-Asian Ocean. Tectonic evolution of the Paleo-Asian Ocean during Late Paleozoic might be divided into three stages. In Early Devonian, the subduction of the Palm-Asian Ocean plate began and some rift basins were formed on the continental margin of southern Altay. The ore-forming processes of such metals as lead, zinc, copper and iron occurred contemporaneously in these basins. At the same time, adakitic magma and copper deposits were produced by partial melting of sub-ducted Paleo-Asian Ocaen plate. In Middle Devonian, forearc basins were formed along with continuous subduction, and copper, lead and zinc metallogenesis occurred in these basins. The collision of Siberian Plate and Kaza-khstan-Junggar Plate occurred in Carboniferous. Some gold deposits and rare metal deposits were formed along the Ertixi suture zone and in southern Ahay due to this extrusion. In Early Permian, extension occurred around the Ertixi suture zone and resulted in some mantle magma activities. Some copper and nickel processes represented by Kelatongke took place in this stage. According to the relationship between tectonic evolution and metallo-genesis of north Xinjiang, the authors hold that polymetallic ore-forming processes and perspective areas in north Xinjiang include lead, zinc, copper and iron deposits in Early Devonian volcano-sedimentary basins of southern Ahay, Early Devonian copper deposits related to adakites, copper polymetallic deposits in Middle Devonian forearc basins, gold deposits and rare metal deposits related to Carboniferous collision within Ertixi suture zone and southern Ahay, and copper-nickel polymetallic deposits related to Permian extension.