新疆准噶尔斑岩铜矿地质特征及成矿作用

Geological characteristics and metallogenesis of porphyry copper deposits in Junggar,Xinjiang

在前人工作基础上,文章综述了新疆准噶尔斑岩铜矿地质特征和成矿背景。划分出4个成矿带,即晚志留世—早泥盆世初琼河坝地区斑岩铜钼矿带、中泥盆世卡拉先格斑岩铜矿带、早石炭世希勒库都克-索尔库都克斑岩-矽卡岩铜钼矿带和晚石炭世包古图斑岩铜矿带。准噶尔成岩成矿时代分为4期,即晚志留世—早泥盆世初(427～411Ma)、中泥盆世(378～374Ma)、石炭纪(332～296Ma)、二叠纪—三叠纪叠加成矿期(269～266Ma;230～200Ma)。斑岩铜矿成矿温度从高温延续到低温(530～120℃),但主要成矿区间在中温阶段(300～180℃);流体盐度w(NaCleq)变化于0.5%～21.75%之间和28.9%～66.76%之间。包古图和云英山矿床成矿流体主要为岩浆水,哈腊苏和玉勒肯哈腊苏矿床成矿流体为岩浆水混合大气降水。硫同位素组成集中于零值附近,指示成矿物质来源于地幔或与地幔有关的岩浆。斑岩铜矿的形成主要与中性、中酸性和酸性斑岩侵入活动有关,其形成的构造环境有大陆岛弧、大洋岛弧和后碰撞环境。

In this paper,the geological characteristics of porphyry copper deposits in Junggar of Xinjiang are reviewed in the metallogenic-tectonic context.These porphyry copper deposits mainly occur in four metallogenic belts：① Late Silurian to the beginning of Early Devonian Qiongheba porphyry Cu-Mo metallogenic belt;② Middle Devonian Kalaxiange＇er porphyry Cu metallogenic belt;③ Early Carboniferous Xilekuduke-Suoerkuduke porphyry-skarn Cu-Mo metallogenic belt;and ④ Late Carboniferous Baogutu porphyry Cu metallogenic belt.The ages of the porphyry intrusions and mineralizations can be divided into four periods：Late Silurian to the beginning of Early Devonian（427～411 Ma）,Middle Devonian（378～374 Ma）,Carboniferous（332～296 Ma） and Permian to Triassic（269～266 Ma;230～200 Ma） superimposed mineralization period.The mineralization temperatures of these porphyry copper deposits range from 530 to 120℃,clustered between 300 to 180℃.The salinities w（NaCleq） range from 0.5% to 21.7% and from 28.9% to 66.76%.The ore-forming fluids of the Baogutu and Yunyingshan deposits were mainly derived from magmatic fluids,whereas the Halasu and Yulekenhalasu deposits were mainly derived from magmatic fluids,with some contributions from meteoric water.Sulfur isotope composition of the porphyry copper deposits is around 0‰,indicating that the ore-forming materials were probably derived from the mantle or the mantle-related magmas.The ore-forming processes of the porphyry copper deposits are closely related to intermediate,intermediate-felsic and felsic porphyry intrusions.The porphyry copper deposits in Junggar were formed in three tectonic settings,i.e.,continental arc,ocean island arc and post-collision settings.