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
론양자지괴서연원고주철양화물동금형광상여대지구조연화
Geotectonic Evolution and the Proterozoic Iron Oxide Copper-Gold Deposits on the Western Margin of the Yangtze Massif
  • 万方数据
    大地构造与成矿学 대지구조여성광학
    GETECTONICA ET METALLOGENIA
    2014年 4期 733-757 ,共25页

    方维萱

    방유훤

    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 鐵氧化物銅金型(IOCG)礦床%大地構造縯化%堿性鐵質輝長巖%闆內洋島玄武巖%裂穀盆地%不整閤麵型礦化
    철양화물동금형(IOCG)광상%대지구조연화%감성철질휘장암%판내양도현무암%렬곡분지%불정합면형광화
    IOCG deposits%geotectonic evolution%alkaline Fe-rich gabbro%OIB%rifted basin%the unconformity-type mineralization
    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)。以白锡腊深部和新塘IOCG矿床为代表,形成IOCG矿床和IOCG矿床的叠加成岩成矿。(4)晋宁-澄江期为多重构造体制耦合与转换格局,扬子地块内部和陆缘具有造山带-沉积盆地-深部地幔柱上涌侵位,深部地幔柱上涌侵位形成的碱性铁质辉长岩具有OIB源区特征,形成了第四期IOCG矿床的成岩成矿高峰期(800±50 Ma),以四川拉拉IOCG矿床受碱性铁质辉长岩侵位与叠加成岩成矿为代表。在澄江期“盆→山”耦合与转换, IOCG矿床和东川型铜矿中进一步发生了盆地流体叠加改造富集(810~700 Ma)。
    탐토화총결료양자지괴서연대지구조연화、원고주중대구조-암장사건여철양화물동금형(IOCG)광상관계,이촉진대심부은복 IOCG 광상감사화신기술연발。재신태고계-고원고계소류구암조정부화불정합면지하,함광층상-사층상감성방해석납장석암중고석SHRIMP U-Pb년령위2520±14 Ma,저충사층상동광상화기상불정합면형Cu-Co-Au- Ag-REE-Fe광체,이운남동천인민철동광상심부소류구암조중동광상위대표。총체상, IOCG광상여양자지괴대지구조연화지간관계위：(1)양자지괴우동천운동(중조운동/Hudsonian Orogeny,1800 Ma)형성료륙각기저。재중원고대초기(1700±50 Ma)발생료지만열물질상용침위적구조-암장사건,도치고양자지괴발생렬해병형성렬곡구조화대륙렬곡분지。재근동서향대륙렬곡분지발육초기,구조동역학특정위화산지참식단함성분。재감성철납질기성암、철갑질조면암화철질휘록휘장암형성과정중,형성료제일기IOCG광상성암성광고봉기(1650±50 Ma),이운남대홍산IOCG광상위대표。(2)재렬곡분지성숙발육기,구조동역학특정위렬함침강성분。인민기화흑산기량차지만열물질상용침위,도치료구조-암장-성암성광사건발생。재철납질기성화산암、철갑질조면암、수하화성탄산암、화산분일-화산열수분류침적상등형성과정중,형성료제이기IOCG광상적성암성광고봉기(1500±50 Ma),이운남이납엄IOCG광상위대표。(3)재소흑정운동/만은구운동(격림위이조산기,1000 Ma±),양자지괴남연형성료근남북향양각부충화륙연측향제압수축체제,감성철질휘장암-휘록암체상용침위,반수동구조기취인성전절대형성화침적분지구조반전,형성구역성불정합면(소흑정운동/만은구운동)화후기침적형-화산침적형철광상,위IOCG광상제삼기성암성광고봉기(1000±100 Ma)。이백석석심부화신당IOCG광상위대표,형성IOCG광상화IOCG광상적첩가성암성광。(4)진저-징강기위다중구조체제우합여전환격국,양자지괴내부화륙연구유조산대-침적분지-심부지만주상용침위,심부지만주상용침위형성적감성철질휘장암구유OIB원구특정,형성료제사기IOCG광상적성암성광고봉기(800±50 Ma),이사천랍랍IOCG광상수감성철질휘장암침위여첩가성암성광위대표。재징강기“분→산”우합여전환, IOCG광상화동천형동광중진일보발생료분지류체첩가개조부집(810~700 Ma)。
    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 <br> 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. <br> 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. <br> Secondly, the mature stage of the rifted basin occurred during the Heishan Period and developed of the Middle Proterozoic Dongchuan Group, during which the tectonic dynamics was characterristics werezed by of basin-rifting subsidence in the rifted basin of mature development period. The event of hot mantle upwelling and emplacement occurred, and resulted in the tectonic-magmatic events and mineralization in the Heishan Period. The second IOCG mineralization peak (1500±50 Ma) was associated with the emplacement of the alkaline Fe-Na-rich basic rocks, Fe-K-rich trachyte, and underwater igneous carbonatite were produced at the sea bed while a variety of as well as marine volcanic lithofacies, such as volcanic eruption facies and volcanic exhalatives sedimentary facies, developed atin the rifted basin. At the same time, the second diagenesis-mineralization peak (1500±50 Ma) for the IOCG deposits started,, and the Yinachang IOCG deposit as theis a representative of the Yinachang IOCG deposit in Yunnan province, China. <br> Thirdly, when the Xiaoheiqing or the Manyingou Orogeny (1000±100 Ma, the Grenville Orogeny) in Yunnan and Sichuan provinces was onset, the nearly north-directed subduction of oceanic crust, i.e., continental margin lateral compressional and shrinkage on the southern margin of the Yangtze massif, was commenced at the beginning of the Grenville Orogeny. Actually, the Grenville Orogeny resulted in the tectonic inversion of the rifted basin. Simultaneously, a series of alkaline Ti-Fe-rich gabbro and diabase intrusions emplaced, and they were accompanied by syn-tectonic brittle-ductile shear zones. The Manyingou orogeny or the Xiaoheiqing orogeny (the Grenville Orogeny) was responsible for the formation of a regional angular unconformity and disconformity in Yunnan and Sichuan provinces. The third peak (1000±100 Ma) of the IOCG diagenesic-metallogenic period could have beenmay be closely related to the alkaline Ti-Fe-rich gabbro and diabase intrusions with syn-tectonic brittle-ductile shear zones. The Baixila and Xintang IOCG deposits in Yunnan province are the representatives of the IOCG deposits. However, these IOCG deposits are of the Ti-high series IOCG deposits, whereas diagenesis-mineralization of the pre-existing IOCG deposits were superimposed by the alkaline Ti-Fe-rich gabbro and diabase emplacement with syn-tectonic brittle-ductile shear zone. <br> Finally, on the one hand, the interiors and margins of the Yangtze massif were typified by the pattern of multiple tectonic system coupling and transformation during the Jinning-Chengjiang movement, that is, conversion of orogenic belt and sedimentary basin with the deep mantle plume upwelling. Therefore, emplacement of alkaline Fe-rich mafic gabbro with OIB source characteristics, led to the formedation of in the fourth peak (800±50 Ma) of the IOCG deposits diagenesis and mineralization period with which is coincident with the peak of regional metamorphism. On the other hand, the IOCG deposits and the Dongchuan-type copper deposits were superposed by Cu-bearing quartz veins derived from basin-fluid, and further enriched by basin-to-mountain transformation and coupling during the Chengjiang movement.
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