Studies On The Mineralization System Of Large Ore-cluster Areas In Qinling Orogenic Belt

Qinling orogenic belt is a giant hybrid orogenic belt situated between two big cratonmassifs(i.e., north China and the Yangtze) of east-west direction which spans in centralmainland China. It containins rich mineral resources and have been widely researched bydomestic and foreign scholars. This thesis is a new study from the perspective of tectonicplates of Qinling orogenic belt which is on the basis of the author，s investigation and researchof Qinling plate tectonics and mineral resources in recent20years, combining previousresearch results. The author analyzes important mineralization system in the tectonic platesevolution process of Qinling orogenic belt for the first time. The important results obtainedfrom the study are as follows:(1)Based on the new discoveries and new knowledge of important tectonic units of theQinling orogenic belt, the author get a clear idea of metallogenic system about themetallogenic setting and the dynamic system of middle Qinling tectonic belt andZhenan-Xunyang basin, that is:(a) On the basis of new undestanding after discoveringMianxian-Lueyang ancient suture line and Liuba-Shanyang main suture zone and consideringthat the Mianxian-Lueyang ancient sutures，s eastern extension turn to the north east byNingshan and deliver to the main suture zone of Shanyang, it is confirmed that the middleQinling orogenic belt between Shangxian-Danfeng tectonic belt and Liuba main suture zoneis a sedimentary wedge of forearc basin caused by Late Paleozoic southern margin of NorthChina sunducting to north, which leads to a clear understanding to the middle Qinlinglead-zinc,gold ore district，s background and metallogenic mechanism of mineralization;(b)Based on the new understanding that at the northern margin of Yangtze Caledonian there wasa "trigeminal" rift system, it is confirmed that Zhenab-Xunyang basin is a superpositioncompound basin of north Dabashan aulacogen fold belt developed on the bases of residualbasin and Xunyang by the insidious Ningshan NEE-Sanyo subduction zone formed by theproliferation Zhenan-slate forearc basin made of a superposition compound basin, whichleads a clear understanding to ore-forming systems background and metallogenic mechanismof the power system of Zhenan-Xunyang basin lead, zinc, gold mineralization zone.(2)Based on these new discoveries and new knowledge, the author reconstructed andrehabilitated the Late Proterozoic and Phanerozoic plate tectonic framework and evolutionaryhistory of Qinling orogenic belt, and considered that there developed a composite "trigeminal"rift system in Qinling orogenic belt and adjacent areas in the late Proterozoic and an radialProterozoic ocean basin. During Phanerozoic, wide Qinling paleo-ocean basin developed at the position of Liuba-Shanyang main suture zone and at the western side of this ocean basindeveloped a trench-arc-basin system which has the characteristics of Japan sea. The east ofthe ocean basin is the northern margin of the Yangtze ancient land (the northwestern margin ofGondwana in the global structure), where developed a "trigeminal" rift system. Its west andnorth-east arms developed Mianxian-Lueyang ancient ocean basin which caused theseparation of the South Qinling micro-continental block from the ancient northern margin ofYangtze Pangea which once drifting toward northwest direction.(3) Based on researching the main ore deposits and important mineralization system ofmiddle Qinling plate tectonic evolution in late Proterozoic and Phanerozoic, the auhtoridentified5major ore-concentrated regions and23major mineralizing systems. In the thesis,the mineralization environment, forming mechanism and the spatial and temporal evolution oftypical deposit characteristics of5major ore-cluster areas and9typical mineral depositsamong them are analyzed and documented in detail. For the small Qinling gold-molybdenumore district, the new idea that a subduction back-arc magmatic-hydrothermal ore-formingsystem is proposed for the first time. It is thought that the middle Qinling lead, zinc, goldcluster areas in late Paleozoic were formed in proliferation forearc basin hot waterore-forming system, the lead, zinc, gold pool in Zhenan-Xun basin of south Qinling wereformed in subducted sediment wedge and residual basin hot water mineralization systems.The author also propose the new understanding that a "hot basement" hot water circulationmineralization system in the MVT-type Pb-Zn ore of margin of the Yangtze for the first time.The thesis Preliminarily studied copper, gold ore cluster of active continental marginmineralization system in the Mianxian-Lueyang-Ningqiang "triangle" area in Neoproterozoic,and identified4major sub-mineralization system.