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| 中冈底斯成矿带查个勒矿床含矿岩体的年代学及成因 | |
| 引用本文： | 王保弟,郭琳,王立全,李冰,黄瀚霄,陈富琦,段志明,曾庆高.中冈底斯成矿带查个勒矿床含矿岩体的年代学及成因[J].岩石学报,2012,28(5):1647-1662. |
| 作者姓名： | 王保弟 郭琳 王立全 李冰 黄瀚霄 陈富琦 段志明 曾庆高 |
| 作者单位： | 1. 成都地质矿产研究所,成都,610081 2. 西藏地勘局区域地质调查大队,拉萨,851400 3. 云南省地质调查院,昆明,650000 |
| 基金项目： | 本文受国家重点基础研究发展规划项目(2009CB421003)、国家自然科学基金(41073033)和中国地质调查局项目(1212011121259、1212011086039)联合资助. |
| 摘 要： | 查个勒矿床是中冈底斯成矿带(即中部拉萨地体)目前发现的一个中-大型矽卡岩+斑岩型矿床,但是其成岩成矿时代一直缺乏年代学约束。本文报道该矿床含矿岩体的LA-ICPMS法锆石U-Pb定年、辉钼矿Re-Os定年、地球化学及Hf同位素数据。花岗斑岩锆石U-Pb年龄明显可分为两组,206Pb/238U加权平均年龄分别为72.2～70.1Ma、65.2～64.4Ma,前者记录了早期的构造岩浆事件,后者代表了岩浆的结晶年龄;而辉钼矿Re-Os等时线年龄为71.5±1.3Ma,所代表的查个勒主成矿期年龄与早期的构造岩浆事件一致;结合65～64Ma时期的岩浆侵位、林子宗群大规模火山活动以及以亚贵拉矿床为代表的成矿作用,表明在印度与欧亚大陆初始碰撞过程中都可能产生不同规模的成矿作用。查个勒含矿岩体具富硅、富钾,贫钛、磷的特征,铝饱和指数(A/CNK)为1.05～1.27,富集大离子亲石元素Rb、Th、U,亏损高场强元素Nb、Ta、Zr、Ti等,并具有不均一的锆石εHf(t)值(-7.9～-2.2)和古老地壳Hf同位素模式年龄(tDMC=1.3～1.6Ga),属于过铝质"S"型花岗岩类。本文认为中冈底斯成矿带南部晚白垩世岩浆活动和成矿作用很可能是与雅鲁藏布江洋盆闭合之后初始碰撞幔源岩浆底侵导致的拉萨微陆块古老地壳物质的部分熔融有关,岩浆在上升过程中有不同程度的分离结晶。同时本文认为冈底斯成矿带成矿元素组合的分带性与新特提斯洋壳俯冲消减-碰撞过程中岩浆产生的源区物质有关。 |
| 关 键 词： | 锆石U-Pb年龄 主碰撞期 查个勒矿床 冈底斯成矿带 |
| 收稿时间： | 2/1/2012 12:00:00 AM |
| 修稿时间： | 4/5/2012 12:00:00 AM |
Geochronology and petrogenesis of the ore-bearing pluton in Chagele deposit in middle of the Gangdese metallogenic belt |
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| WANG BaoDi,GUO Lin,WANG LiQuan,LI Bing,HUANG HanXiao,CHEN FuQi,DUAN ZhiMing and ZENG QingGao.Geochronology and petrogenesis of the ore-bearing pluton in Chagele deposit in middle of the Gangdese metallogenic belt[J].Acta Petrologica Sinica,2012,28(5):1647-1662. | |
| Authors: | WANG BaoDi GUO Lin WANG LiQuan LI Bing HUANG HanXiao CHEN FuQi DUAN ZhiMing and ZENG QingGao |
| Institution: | Chengdu Institute of Geology and Mineral Resources, Chengdu 610081, China;Regional Geological Surveying Party, Bureau of Geology and Exploration of Tibet, Lhasa 851400, China;Chengdu Institute of Geology and Mineral Resources, Chengdu 610081, China;Yunnan Institute of Geological Survey, Kunming 650011, China;Chengdu Institute of Geology and Mineral Resources, Chengdu 610081, China;Regional Geological Surveying Party, Bureau of Geology and Exploration of Tibet, Lhasa 851400, China;Chengdu Institute of Geology and Mineral Resources, Chengdu 610081, China;Regional Geological Surveying Party, Bureau of Geology and Exploration of Tibet, Lhasa 851400, China |
| Abstract: | Chagele skarn-porphyry deposit have been recently discovered in Tibet,which is located in middle of the Gangdese(or central Lhasa Terrane) metallogenic belt.However,it is absence of the high-precision chronology of porphyritic intrusion and deposit so far.The zircon U-Pb and Molybdenites Re-Os ages are reported in this study,with the bulk-rock major element,trace element and zircon Hf isotopic data on the ore-bearing rocks in Chagele deposit.Zircon U-Pb age of granitic porphyry is divided into two groups,72.2 ～ 70.1Ma and 65.2 ～ 64.4Ma,which probably record the early tectonic-magmatic event and the latter magmatic crystallization,respectively.Molybdenites Re-Os isotopic dating shows that the molybdenite is formed at 71.5 ± 1.3Ma,which is consistent with the early magmatism in the studying area.These new data in this studying,combing with the extensive volcanism of Linzizong Group,suggest that different sizes of mineralization were formed at different stages of the entire collision process between India and Eurasia.The ore-bearing porphyry of Chagele deposit have high SiO2,K2O,Rb,Th,and U contents,coupled with low TiO2,P2O5 contents and strong negative anomalies of Ba,Nb,Ta,Sr,P and Eu,variable εHf(t)(-7.9 ～-2.2) and ancient tDMC(1.3 ～ 1.6Ga).These geochemical features suggest that the samples of Chagele deposit are similar to the peraluminous of S-type granites.This paper suggests that the Late Cretaceous magmatism and mineralization in middle of the Gangdese metallogenic belt could be produced by partial melting of ancient crust materials of the Lhasa microcontinent accompanying with fractional crystallization,which are probably induced by underplating of mantle-derived magmas in the main collision setting of the collision between Indian and Eurasia.We also believe that the zonation of the ore-forming element in the Gangdese metallogenic belt is associated with source material of magma during subduction or collision process of the Neo-Tethyan oceanic. |
| Keywords: | Zircon U-Pb dating Main collisional period Chagele deposit Gangdese metallogenic belt |
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