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引用本文:瞿泓滢,刘建楠,裴荣富,何书跃,周淑敏,王辉,周建厚. 青海祁漫塔格成矿带与虎头崖铜铅锌多金属矿床有关的二长花岗岩体热年代学研究[J]. 中国地质, 2018, 45(3): 511-527.
QU Hongying,LIU Jiannan,PEI Rongfu,HE Shuyue,ZHOU Shumin,WANG Hui,ZHOU Jianhou. Thermochronology of the monzonitic granite related to the Hutouya Cu-PbZn polymetallic deposit in Qiman Tage, Qinghai Province[J]. Geology in China, 2018, 45(3): 511-527(in Chinese with English abstract).
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青海祁漫塔格成矿带与虎头崖铜铅锌多金属矿床有关的二长花岗岩体热年代学研究
瞿泓滢1, 刘建楠1, 裴荣富1, 何书跃2, 周淑敏3, 王辉1, 周建厚1
1.中国地质科学院矿产资源研究所, 国土资源部成矿作用与资源评价重点实验室, 北京 100037;2.青海省第三地质矿产勘查院, 青海 西宁 810029;3.青海大学地质工程系, 青海 西宁 810016
摘要:
虎头崖铜铅锌多金属矿区是青海祁漫塔格地区较为典型的兼具内接触带矽卡岩亚型和外接触带矽卡岩亚型矿化的矿区,其岩浆侵入活动强烈,不同时代含碳酸盐岩的地层出露多,铁铜锡钼铅锌等金属成矿元素组合复杂,找矿潜力巨大。本次研究依据岩体热年代学理论,即岩体总能量与其规模成正比,规模愈大的岩体其热能量愈高,热效应愈大,冷速率相应愈低。冷速率通过同一岩体不同矿物的封闭温度计算得出。选取虎头崖矿区黑云母和斜长石两种矿物进行Ar-Ar年龄测定,样品HTY002黑云母和斜长石40Ar-39Ar坪年龄分别为(233.6±2.2)Ma和(231.5±1.3)Ma,样品HTY016黑云母和斜长石40Ar-39Ar坪年龄分别为(229.6±2.3)Ma和(219.3±1.8)Ma,样品HTY019黑云母和斜长石40Ar-39Ar坪年龄分别为(224.7±2.6)Ma和(222.2±2.2)Ma,计算得到二长花岗岩冷速率分别为57.14℃/Ma、11.65℃/Ma、48.00℃/Ma。当侵入岩体的成分相近时,其侵位时的单位热能可能差别很小,而岩体的总能量与其规模是成正比的,所以不同规模岩体的总能量是有差别的,规模愈大的岩体其热能量也愈高,与围岩达到平衡所需的时间愈长,热效应愈大,冷速率相应愈低。针对不同样品和不同矿物计算虎头崖矿区二长花岗岩体冷速率比较接近,其冷速率相对较快(介于11~57℃/Ma),可知其热效应较大,具有一定的成矿潜力。
关键词:  封闭温度  冷速率  热效应  岩体热年代学  青海祁漫塔格虎头崖
DOI:10.12029/gc20180307
分类号:P618.41~43;P588.12+1;P597+.3
基金项目:中国地质调查局地质调查项目(DD20160007)资助。
Thermochronology of the monzonitic granite related to the Hutouya Cu-PbZn polymetallic deposit in Qiman Tage, Qinghai Province
QU Hongying1, LIU Jiannan1, PEI Rongfu1, HE Shuyue2, ZHOU Shumin3, WANG Hui1, ZHOU Jianhou1
1.MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;2.No.3 Institute of Geology and Mineral Resources, Xining 810029, Qinghai, China;3.Department of Geological Engineering, Qinghai University, Xining 810016, Qinghai, China
Abstract:
The Hutouya mining area in Qiman Tage of Qinghai Province owns the characteristics of inner-and exo-contact belt skarn subtype mineralization. The magmatic intrusive activities are strong in this area. The carbonatite formation of different ages is exposed extensively. The combination of metal metallogenic elements is complex. The potential for the ore prospecting is great. This study is based on the thermochronology theory for rock bodies. The total energy of rock bodies is proportional to its scale. The thermal energy is larger as the scale of rock bodies is larger, the thermal effect is larger as the thermal energy is larger, and the cooling rate is larger as the thermal effect is larger. The cooling rate is calculated via the closure temperature of different minerals. The authors studied Ar-Ar ages of biotite and plagioclase from the Hutouya mining area. The 40Ar-39Ar plateau ages of biotite and plagioclase from the HTY002 monzonitic granite sample related to mineralization are 2(33.6 ±2.2) Ma and (231.5 ±1.3) Ma, respectively. The 40Ar-39Ar plateau ages from the HTY016 sample are (229.6±2.3) Ma and (219.3±1.8) Ma, respectively. The 40Ar-39Ar plateau ages of the HTY019 sample are (224.7±2.6) Ma and (222.2±2.2) Ma, respectively. The calculated cooling rates are 57.14℃/Ma, 11.65℃/Ma, and 48.00℃/Ma. Where the compositions of the intrusive rocks are similar, the differences of the unit thermal energies of their emplacement are very small. Because the total energy of rock bodies is proportional to its scale, the total energies of rock bodies of different scales are different. The thermal energy of large rock bodies is large, the time of balance with the surrounding rock is long, the thermal effect is large, and the cooling rate is low. The cooling rates of different minerals from the Hutouya mining area are similar. The values of the cooling rates are high, varying from 11 to 57℃/Ma, so the thermal effect is large. It is thus concluded that the potential for the ore prospecting is great in the Hutouya mining area.
Key words:  closure temperature  cooling rate  thermal effect  thermochronology  Hutouya mining area in Qimantag,Qinghai Province