智利铁氧化物铜金型矿床成矿规律、控制因素与成矿演化

Metallogenic Regulations,Controlling Factors,and Evolutions of Iron Oxide Copper and Gold Deposits in Chile

智利中生代铁氧化物铜金型(IOCG)矿床成矿带位于海岸科迪勒拉山带,与斑岩铜金和浅成低温热液型金银矿床共同组成了南美安第斯型活动大陆边缘上成矿系统组合。在成矿时代上,IOCG矿床成矿时代集中在175.6～141,140～100和99～66 Ma BP。IOCG矿床位于弧前盆地、主岛弧带和弧后盆地等五级构造单元中;而斑岩铜金和浅成低温热液型金银矿床位于主岛弧带和弧后盆地中,与IOCG矿床成矿带成对出现。综述了智利超大型IOCG矿床研究和勘查进展,认为智利IOCG矿床主要为富铁质岩浆的火山喷溢作用、岩浆热液—盆地流体混合成矿和岩浆热液成矿作用等3种端元类型。侏罗—白垩纪弧前盆地、主火山岛弧带和弧后盆地等五级构造单元是IOCG矿床定位构造,在晚白垩世发生构造反转后,在安第斯大陆边缘从伸展构造体制转变为走滑挤压收缩构造体制,同时形成了平行于岛弧带的阿卡塔玛(AFZ)断裂系统,AFZ断裂系统导致弧前盆地—主岛弧带—弧后盆地发生构造变形并伴有同构造期岩浆侵入,主岛弧带岩浆活动停滞,晚白垩世深成岩浆弧向东迁移,在岛弧带和弧后盆地反转过程中因岩浆—构造叠加程度不同,形成了IOCG矿床叠加成矿序列,同期,白垩纪斑岩型铜金矿床和浅成低温热液型金银矿床相伴形成。提出富铁基性—超基性岩、IOCG矿床和斑岩型铜金矿床等与弧后盆地构造变形的动力学机制是今后的研究方向。

The Mesozoic metallogenic Coastal Cordillera Range in Northern Chile. beh of iron-oxide copper and gold （IOCG） deposits is located at the IOCG system, porphyry Cu-Au and epithermal Au-Ag systems consist of co-associations of metallogenic system on the Andean-type active continental margin. However, metallogenic ages of IOCG deposits may be classified into three main groups from 175.6 - 141 Ma BP, 140 - 100 Ma BP, and 99 66 Ma BP. IOCG deposits are located at front-arc basin, main arc zone, and back-arc basin, whereas the Creta- ceous porphyry Cu-Au and epithermal Au-Ag systems, as a pair of the IOCG system, are located at the deformation of the main arc zone and the back-arc basin. After reviews on the study and exploration achievement for IOCG deposng of magmatie and basin-fluids, and magmatie fluids. The Jurassic-Cretaceous front-arc basin, main are zone, and baits, it may be considered that the end member of the Chilean IOCG deposits might have been formed by eruption of the Fe-rieh magma, mixick-are basin may be the fifth-order tectonic unit for the location-controlling tectonics of IOCG deposits during evolutions of the Andean-type active continental margin. The Andean continental margin might have changed from extensional realm into strike-slip transpression realm after inversion by the end of the Late Cretaceous time. At the same time, Aeatama fault system （AFZ） were onset paralleling to the main are zone. Therefore, all of them, the front-are and back-basin, and main are zone, were undergone their deformation by AFZ activity as well as synteetonie magmatie intrusions. Magmatie intrusion of the Jurassic-Cretaceous main arc zone was aborted, and the Late Cretaceous magmatic intrusions were east-directed migration. Simultaneously, superimposing system of IOCG deposits might form in the deformations of the main are and back-are basin by different superimpo- sing degrees of tectonic deformation and magmatie intrusion during their inversion processes. Moreover, porphyry Cu-Au and epithermal Au-Ag systems, as pairs of the metallogenie zones at the east part of the IOCG system, were formed in the calc-alkaline magmatic zone. It suggested that the relationships among the Fe-rich basic to ultrabasic rocks, IOCG deposits and porphyry Cu-Au deposits related to dynamics for tectonic deformation of the back-arc ba- sin should be focused on the study in the future.