安徽铜陵地区虎山岩体矿物成分特征及其锆石U-Pb年代学  

Mineral composition and zircon U-Pb dating of the Hushan intrusion in Tongling area, Anhui Province

作　　者：雷敏[1] 吴才来[1] 秦海鹏[1] 王楠[1] 张昕[1] 陈红杰[1] 

机构地区：[1]大陆构造与动力学国家重点实验室,中国地质科学院地质研究所,北京100037

出　　处：《中国地质》2015年第5期1274-1292,共19页Geology in China

基　　金：国家专项(SinoProbe-05-05);公益性行业科研专项课题(201211095-4);国家自然科学基金项目(40921001、41302266);中国地质调查局项目(1212011120160、1212010918007)共同资助

摘　　要：铜陵地区虎山岩体主要由石英二长闪长岩和花岗闪长斑岩组成,属高钾钙碱性系列中酸性侵入岩。本文对虎山岩体进行了LA-ICP-MS锆石U-Pb定年,结果表明,虎山石英二长闪长岩和花岗闪长斑岩侵入时代分别为（143.2±1.2）Ma和（145.3±1.2）Ma,属晚侏罗—早白垩世,与中国东部J-K岩浆事件相呼应,并且,虎山岩体存在两次岩浆侵入活动,早期形成的花岗闪长斑岩的年龄为（145.3±1.2）Ma,与铜陵矿集区瑶山花岗闪长斑岩的年龄（146.0±0.9）Ma在误差范围内一致,晚期形成的石英二长闪长岩为（143.2±1.2）Ma,与区内的铜官山和天鹅抱蛋山岩体的年龄（142±1）Ma和（141.7±1）Ma一致。岩石地球化学及矿物温压计计算结果表明,岩浆结晶的温度为768~838°C、压力为3.44×108~5.42×108Pa,虎山岩体属幔源岩浆和壳源岩浆混合成因,且混合作用发生在11~18 km的浅位岩浆房。Mesozoic intermediate-acid intrusive rocks in Hushan intrusion of Tongling area belong to the high potassium（K） calcalkaline series, with main rock types being quartz monzodiorite and granodiorite porphyry. LA- ICP- MS zircon U- Pb dating of Hushan intrusion shows that the emplacement age of quartz monzodiorite and granodiorite porphyry are（143.2±1.2）Ma and（145.3±1.2）Ma respectively, belonging to Late Jurassic- Early Cretaceous. These data are consistent with eastern China＇s J- K magmatic event. In addition, Hushan body has experienced two times of magma intrusion activities. The age of early granodiorite porphyry（145.3±1.2）Ma is consistent with the age of Yaoshan granodiorite porphyry（146.0±0.9） Ma in the Tongling ore district, and the age of late quartz monzodiorite（143.2±1.2）Ma is consistent with that of Tongguanshan and Tianebaodanshan（142±1）Ma,（141.7±1）Ma）.From the study of geochemistry and plagioclase-hornblende thermobarometry, the authors conclude that the magma crystallization temperature and the corresponding pressure varied in the range of 768~838° C and 3.44 × 108~5.42 × 108 Pa, respectively. Hushan intrusion was derived from the mixture of the mantle magma and crustal magma, with their corresponding depths being 11~18 km.

关 键 词：花岗岩类 矿物学 LA-ICP-MS锆石U-PB定年 温压计 铜陵 虎山岩体 

分 类 号：P588.12[天文地球—岩石学] P597[天文地球—地质学]