豫西崤山白石崖岩株的深部过程——锆石年龄谱和稀土元素证据  

Deep tectonic processes of the Baishiya stock in Xiaoshan Mountains,western Henan Province--Evidences from zircon U-Pb age sprctrum and rare earth elements

作　　者：梁涛 卢仁 LIANG Tao;LU Ren(Henan Academy of Geology,Zhengzhou,450016;Henan Engineering Technology Center on Non-ferrous Metals Ore-prospecting,Zhengzhou,450016;Henan Key Laboratory of Metal Mineral Mineralization Geological Processes and Resource Utilization,Zhengzhou,450016;Key Laboratory of Deep Ore-prospecting technology Research for Non-ferrous Metals of Henan Province,Zhengzhou,450016)

机构地区：[1]河南省地质研究院,郑州450016 [2]河南省有色金属深部找矿工程技术研究中心,郑州450016 [3]河南省金属矿产成矿地质过程与资源利用重点实验室,郑州450016 [4]河南省有色金属深部找矿勘查技术研究重点实验室,郑州450016

出　　处：《地质论评》2023年第5期1741-1762,共22页Geological Review

基　　金：国家自然科学基金资助项目(编号:U1504405);河南省有色金属地质矿产局首批科技创新专项资金项目(编号:KCXM202109);河南省自然资源科技攻关项目(编号:2022-398-8);河南省科技计划项目(编号:162300410065);河南省国土资源厅科技攻关项目(编号:2016-08、2014-06、2011-622-25和2011-622-36)的成果。

摘　　要：崤山北部早白垩世侵入岩的简单年龄结果中包含了复杂地质信息,6个岩株的侵位年龄集中于~130 Ma和~145 Ma两期,复杂的单颗粒锆石年龄谱为反演区域构造背景提供了新途径。白石崖岩株锆石的U-Pb年龄和微量元素特征不仅对探讨其岩石成因和深部过程具有重要作用,而且为建立崤山北部燕山期侵入岩的精细的年代学框架和整合的成因模型提供新限定。白石崖岩株定年样品BSY03为斑状黑云母二长花岗岩,3次LA-ICP-MS锆石U-Pb测试中分析了77个测点,其中73个有效测点的年龄值分成~132 Ma(15个)、~145 Ma(49个)和~158 Ma(9个)3个年龄组,形成了锆石年龄谱,最晚一组加权平均年龄132.1±1.0 Ma为白石崖岩株的形成时代。3组年龄锆石均显示了轻稀土亏损和重稀土富集的特征,整体为Ce正异常及Pr、Nd负异常,~145 Ma和~158 Ma两组锆石的稀土总量分别为694×10^(-6)~2213×10^(-6)(平均值1309×10^(-6))和950×10^(-6)~1849×10^(-6)(平均值1360×10^(-6)),~132 Ma组锆石的稀土总量变化范围介于429×10^(-6)~2210×10^(-6),平均值为1495×10^(-6)。3组锆石总体的形成温度为539~748℃;~158 Ma组锆石的温度较高,为601~748℃(平均值662℃);~145 Ma组和~132 Ma组锆石的温度分别介于539~717℃(平均值629℃)和553~701℃(平均值633℃)。锆石测点的Er、Yb、Lu和Y含量随年龄由早及晚的整体变化趋势均为升高,~132 Ma和~145 Ma组锆石的Ce^(4+)/Ce^(3+)值分别介于13.2~121(平均值69.7)和27.6~107(平均值70.3),~158 Ma组锆石的Ce^(4+)/Ce^(3+)值介于3.53~81.4,其由早及晚的整体趋势均为先升高后降低。白石崖岩株的形成受控于崤山北部岩石圈拆沉作用,深部岩浆/流体因此得以释放,促成上部处于未完全固结晶粥状态的岩浆/流体库发生混合再活化作用,重获上侵能力的岩浆/流体卷携多期锆石(如~158 Ma和~145 Ma的锆石)在浅部构造有利部位固结成岩,并晶出~132 Ma锆石。Objectives:The simple zircon U-Pb dating results of the early Cretaceous intrusives in the northern Xiaoshan Mountains contained complex geological information.The emplacement zircon U-Pb ages of the six granitic stocks were simple and clear,forming two periods of~130 Ma and~145 Ma.The complex single grain zircon age spectrum provided a new way to consider the regional tectonic background.The zircon U-Pb ages and trace element characteristics from the Baishiya stock were not only important for discussing their petrogenesis and deep processes,but also significant for establishing a precise chronological framework and an integrated genetic model of Yanshanian intrusives in the northern Xiaoshan Mountains.Methods:According to the detailed field obversations of the Bashiya stock in the Xiaoshan Mountain,western Henan Province,the zircon U-Pb dating and rare earth elements were analysed.Results:The dating sample named BSY03 from the Baishiya stock was porphyritic biotite monzogranite.There are 77 zircon spots in three tests were analysed,and 73 results of them were adjacent to n(207Pb)/n(235U)—n(206Pb)/n(238U)concordia,whose U-Pb ages were clustered in three groups of the~132 Ma(15 spots),~145 Ma(49 spots)and~158 Ma(9 spots).The zircon age spectrum was formed.The weighted average age of the last group suggested the formation age of the Baishiya stock was 132.1±1.0 Ma in the early Cretaceous.The chondritenormalized distribution of the rare earth elements(REEs)for the three zircon groups,the characteristics of light REEs depletion and heavy REEs enrichment were shown,and the positive anomaly of Ce and negative anomalies of Pr and Nd were obvious for the most zircon spots.The total REE contents of~145 Ma and~158 Ma groups were 694×10^(-6)~2213×10^(-6)with average of 1309×10^(-6)and 950×10^(-6)~1849×10^(-6)with average of 1360×10^(-6),respectively.The total REE contents of~132 Ma group were from 429×10^(-6)to 2210×10^(-6),and mean value was 1495×10^(-6).The formation temperatures of the zircons generally range

关 键 词：白石崖 锆石U-Pb年龄谱 锆石稀土元素 岩浆/流体混合 岩石圈拆沉 崤山 

分 类 号：P597.3[天文地球—地球化学] P534.53[天文地球—地质学] P588.12