山西吕梁地区狐偃山碱性杂岩体LA-ICP-MS锆石U-Pb年龄及其地质意义

发布时间：2018-07-04 17:57

本文选题：碱性杂岩体 + LA-ICP-MS锆石U-Pb测年　；参考：《地质通报》2017年Z1期

【摘要】：为获取狐偃山碱性岩浆活动的时限,对狐偃山碱性杂岩体早晚2期侵入体进行LA-ICP-MS锆石U-Pb测年。结果显示,早期侵入体二长岩的~(206)Pb/~(238)U年龄加权平均值为127±1Ma(MSWD=3.7),属于早白垩世早期;晚期侵入体正长岩的~(206)Pb/~(238)U年龄加权平均值为114±4Ma(MSWD=3.5),属于早白垩世晚期。二长岩岩浆活动对应于华北克拉通中部碱性岩浆活动的高峰期(约130Ma),正长岩则代表华北克拉通中部最后一期碱性岩浆活动的时间(约114Ma);华北中部碱性岩浆活动与东部发生的强烈岩浆活动的时间一致,对应于华北克拉通岩石圈减薄的峰期。捕获岩浆成因锆石2.5~2.4Ga的年龄,对应华北克拉通化的时期;2.2~2.1Ga的继承锆石年龄,代表华北在2.5Ga左右克拉通化之后于2.3~2.0Ga经历的一次陆内拉伸-裂谷-岩浆事件;约1.8Ga继承锆石的年龄,是华北克拉通发生在陆内裂谷背景下的大规模岩浆作用的表现;232~220Ma的继承锆石年龄,代表晚三叠世华北克拉通发生的一期岩浆-构造热事件的时间。
[Abstract]:In order to obtain the time limit of alkaline magmatic activity in Huyan Mountain, LA-ICP-MS zircon U-Pb dating was carried out on the intrusions in the morning and evening of the Huyan Mountain alkaline complex. The results show that the weighted average of ~ (206) Pb / ~ (238) U age of the early intrusive xenoliths is 127 卤1 Ma (MSWDU 3.7), which belongs to the early Cretaceous period, and the weighted average of ~ (206) PbP ~ (238) U age of the late intrusive syenite is 114 卤4 Ma (MSWD3.5), belonging to the late early Cretaceous. The magmatic activity of the ergite corresponds to the peak of the alkaline magma activity in the central part of the North China Craton (about 130 Ma), while the syenite represents the time of the last alkaline magmatic activity in the central part of the North China Craton (about 114 Ma). Strong magmatic activity in the eastern part of the country occurred at the same time, Corresponding to the peak period of lithosphere thinning in North China Craton. The age of capture magmatic zircon of 2.5 and 2.4 Ga corresponds to the inherited zircon age of 2.2and 2.1Ga in the period of North China cratonization, which represents an intracontinental extension-rift magmatic event in 2.3Ga-2.0Ga and an inherited zircon age of about 1.8Ga. It represents the inherited zircon age of 232n 220 Ma and represents the time of the first magmatic tectonic-thermal event of the North China Craton in the late Triassic.
【作者单位】：太原理工大学矿业工程学院;
【基金】：中国地质调查局项目《山西中北部新生代断陷盆地群页岩气资源调整调查及综合分析》(编号:12120113039900-02) 太原理工大学青年基金项目《吕梁山中段中生代狐偃山碱性偏碱性杂岩群侵位机制及动力学》(编号:2014QN005)
【分类号】：P597.3;P588.15

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