西藏冈底斯东段驱龙—甲马地区构造—岩浆演化与成矿

Tectonic—Magmatic Evolution and Mineralization of the Qulong—Jiama Areas in Eastern Section of Gangdese Mountains,Xizang(Tibet)

通过年代学的研究,在西藏冈底斯东段驱龙—甲马地区叶巴组火山岩、底日玛矿区的闪长岩、丢嘎地区的花岗岩、象背山矿区和驱龙矿区的含矿花岗斑岩中,获得的LA-ICP-MS锆石U-Pb年龄分别为154.8±6.8Ma、52.39±0.95Ma、50.8±1.2Ma、14.35±0.49Ma和15.48±0.42Ma。结合岩石地球化学特征,详细总结该区域的构造—岩浆演化与成矿为:1在新特提斯洋向北俯冲的作用下,形成了叶巴组火山岩,在这个阶段形成了与早—中侏罗世岛弧型中酸性火山岩—浅成岩建造有关的铜、金、银、铅锌矿床成矿亚系列;2在印度—亚洲大陆主碰撞阶段形成了林子宗组火山岩和大量发育的侵入岩,在这个阶段形成了与古新世—始新世中酸性火山—中浅成岩浆建造有关的铅锌、银、钼、钨、铁矿床成矿亚系列;3在后碰撞伸展的体制下,侵入了大量含矿斑岩体,这个阶段主要形成与中新世中酸性浅成岩浆建造有关的铜、钼、铅锌、钨、金、银矿床成矿亚系列,这是研究区主要的成矿类型。最后认为是印度—亚洲大陆碰撞导致了大规模斑岩成矿作用。

Based on the research of geochronology,the writer has determined the ages of Yeba volcanic rocks that in the Qulong—jiama ears,and Dirima intrusive rocks and Diuga granites,as well as the Ore-bearing porphyry in Qulong and Xiangbeishan by Zircon U-Pb LA-ICP-MS. And the results are 154. 8 ± 6. 8Ma,52. 39 ± 0. 95 Ma,50. 8 ± 1. 2Ma,14. 35 ± 0. 49 Ma and 15. 48 ± 0. 42 Ma. Connecting the research of petrology and geochemistry,this paper studies the the space frame of tectonic—magmatic as well as the Mineralization of different stages in these areas. First of all,on the effect of Ocean—continent transition northward subduction of Neo-Tethys Ocean,it has formed a broad region of the Yeba volcanic rocks. At this stage,the major subserieses include Cu—Au—Ag—Pb—Zn subeseries related to Early—Middle Jurassic arc-type intermediate—felsic volcanic—supergene rock.Secondly,at ocean—continent collision conversion stage,it formed Linzizong Group volcanic and a lot of intrusive rocks. At this stage,it could help to create the Pb—Zn—Ag—Mo—W—Fe subseries related to Paleocene—Eocene intermediate—felsic volcanic rock and intermediate—supergene rock formation. Thirdly,in the postcollisional period,at the mechanism of extension,a large number of ore-bearing porphyry intrude upon the crust.At this stage, it could help to create the Cu—Mo—Pb—Zn—W—Au—Ag subseries related to Miocene intermediate—felsic supergene rock formation. They are the main mineralization types,and a large number of porphyry deposits were formed in Tibetan plateau as the result of collision between the India and the Lhasa plates.