论扬子地块西缘元古宙铁氧化物铜金型矿床与大地构造演化  

Geotectonic Evolution and the Proterozoic Iron Oxide Copper-Gold Deposits on the Western Margin of the Yangtze Massif

作　　者：方维萱[1,2] 

机构地区：[1]北京矿产地质研究院,北京100012 [2]昆明中色地科矿产勘查有限责任公司,云南昆明650224

出　　处：《大地构造与成矿学》2014年第4期733-757,共25页Geotectonica et Metallogenia

基　　金：科技支撑计划项目"东川-易门铜矿山深部及外围勘查技术研究"(编号:2006BAB01B090);科技部科研院所技术开发专项"铁氧化物铜金型矿床元素赋存状态及岩相构造学填图技术研发"(编号:2011EG115022);昆明中色地科矿产勘查有限责任公司研发项目(编号:KZSDK-2008-1)联合资助

摘　　要：探讨和总结了扬子地块西缘大地构造演化、元古宙重大构造-岩浆事件与铁氧化物铜金型（IOCG）矿床关系,以促进对深部隐伏 IOCG 矿床勘查和新技术研发。在新太古界-古元古界小溜口岩组顶部和不整合面之下,含矿层状-似层状碱性方解石钠长石岩中锆石SHRIMP U-Pb年龄为2520±14 Ma,这种似层状铜矿床和其上不整合面型Cu-Co-Au- Ag-REE-Fe矿体,以云南东川因民铁铜矿床深部小溜口岩组中铜矿床为代表。总体上, IOCG矿床与扬子地块大地构造演化之间关系为：（1）扬子地块于东川运动（中条运动/Hudsonian Orogeny,1800 Ma）形成了陆壳基底。在中元古代初期（1700±50 Ma）发生了地幔热物质上涌侵位的构造-岩浆事件,导致古扬子地块发生裂解并形成裂谷构造和大陆裂谷盆地。在近东西向大陆裂谷盆地发育初期,构造动力学特征为火山地堑式断陷成盆。在碱性铁钠质基性岩、铁钾质粗面岩和铁质辉绿辉长岩形成过程中,形成了第一期IOCG矿床成岩成矿高峰期（1650±50 Ma）,以云南大红山IOCG矿床为代表。（2）在裂谷盆地成熟发育期,构造动力学特征为裂陷沉降成盆。因民期和黑山期两次地幔热物质上涌侵位,导致了构造-岩浆-成岩成矿事件发生。在铁钠质基性火山岩、铁钾质粗面岩、水下火成碳酸岩、火山喷溢-火山热水喷流沉积相等形成过程中,形成了第二期IOCG矿床的成岩成矿高峰期（1500±50 Ma）,以云南迤纳厂IOCG矿床为代表。（3）在小黑箐运动/满银沟运动（格林威尔造山期,1000 Ma±）,扬子地块南缘形成了近南北向洋壳俯冲和陆缘侧向挤压收缩体制,碱性铁质辉长岩-辉绿岩体上涌侵位,伴随同构造期脆韧性剪切带形成和沉积盆地构造反转,形成区域性不整合面（小黑箐运动/满银沟运动）和后期沉积型-火山沉积型铁矿床,为IOCG矿床第三期成岩成矿高峰期（1000±100 Ma）。以�In order to promote the exploration and develop new exploration techniques for IOCG deposits at depth, the relationships between the Proterozoic iron oxide copper gold （IOCG） deposits on the western margin of the Yangtze massif, and the Proterozoic major tectonic-magmatic events along with their tectonic evolution are discussed in this paper. There is an unconformity between the Yinmin Formation of the Middle Proterozoic Dongchuan Group and the Late Archean to the early Proterozoic Xiaoliukou Association. SHRIMP U-Pb dating of zircon from the layered-bedded albitite in the Archean to the early Proterozoic Xiaoliukou Association which hosts the Cu-Co-Au-Ag-REE-Fe orebodies yields an age of 2520±14 Ma. Nevertheless, issues such as the unconformity-type of the Cu-Co-Au-Ag-REE-Fe mineralization and formation mechanism of hydrothermal breccia in the Xiaoliukou Association in Yunnan province are still open to debate. The relationships between the Proterozoic IOCG deposits and major tectonic-magmatic events of the Yangtze massif are propsed as the followings. Firstly, after following the Dongchuan Orogenorogenic movementy （Hudsonian Orogeny, ca. 1800 Ma±）, the basement tectonic layer of the continental crust on the Yangtze massif could have been formed. However, Tectonictectonic-magmatic emplacement events of the mantle upwelling occurred in the early Mesoproterozoic age （1700±50 Ma）, resulted the Yangtze massif split and the formation of the rifted basin. Basin-tectonic dynamics for the east-west-trending rifted basin was characterized by the volcano-graben basin at the early stage of the continental rifted basin. The first peak of IOCG diagenesis-mineralization period （1650±50 Ma） took place during the emplacement of the alkaline Fe-Na-rich basic rocks, Fe-K-rich trachyte, the Fe-rich diabases and gabbros along with the contemporary eruptions of volcanic rock of similar compositions, as exampified by the Dahongshan IOCG deposit in Yunnan province, China. Secondly, the mature stage of the rifted

关 键 词：铁氧化物铜金型(IOCG)矿床 大地构造演化 碱性铁质辉长岩 板内洋岛玄武岩 裂谷盆地 不整合面型矿化 

分 类 号：P611[天文地球—矿床学]