南岭地区五团岩体锆石LA-ICP-MS U-Pb定年、地球化学特征及其地质构造意义

发布时间：2018-04-25 09:31

  本文选题：锆石LA-ICP-MS + U-Pb年龄　； 参考：《地质科技情报》2017年06期

【摘要】：五团岩体位于南岭地区西段,主要岩性为黑云母二长花岗岩。利用LA-ICP-MS微区原位测试技术,对五团岩体黑云母二长花岗岩进行了锆石U-Pb定年及CL显微结构分析。结果表明:2件锆石样品的~(206)Pb/~(238)U加权平均年龄分别为(211±0.95)Ma(MSWD=0.08)和(227±3.2)Ma(MSWD=1.9),结合前人获得的年龄数据,认为岩体形成于晚三叠世中期且具有多次侵位;岩石具高硅、富铝、高钾特征,w(SiO_2)70.54%~72.55%,平均71.67%;w(Al_2O_3)13.62%~14.55%,平均14.03%;w(K_2O)4.18%~5.28%,平均4.85%;全碱(Na_2O+K_2O)7.09%~7.89%,平均7.51%;K_2O/Na_2O比值1.44~4.51,平均2.02;总体属铁质、高钾钙碱性-钾玄岩系列过铝质花岗岩类;Ba、Nb、Sr、P、Ti表现为明显亏损,Rb、Th、U、K、La、Ce、Nd、Zr、Hf、Sm、Y、Yb、Lu等则相对富集,w(∑REE)62.07×10~(-6)~149.58×10~(-6),平均126.68×10~(-6),δEu值0.26~0.50,地球化学特征表明花岗岩为S型花岗岩,源岩主要为中、上地壳变质杂砂岩;花岗岩微量元素构造环境判别图解主要显示为后碰撞构造环境。基于岩石成因、构造环境判别以及区域构造演化过程,推断五团岩体形成于印支晚期后碰撞环境,是加厚地壳在碰撞应力减弱、深部压力降低等条件下部分熔融的产物。
[Abstract]:The Wutuan rock body is located in the west section of Nanling area, and the main lithology is biotite monzogranite. Zircon U-Pb dating and CL microstructure analysis of biotite monzogranites in Wuduan rock mass were carried out by using LA-ICP-MS microregional in-situ measurement technique. The results show that the weighted mean ages of 2 zircon samples are 211 卤0.95MaMMSWDN0.08) and 227 卤3.2MaMSWDU respectively. Combined with the obtained age data, it is considered that the rock mass was formed in the middle late Triassic and has multiple intrusions, and the rocks are high in silicon, rich in aluminum, and rich in aluminum. 72.55, 72.55 and 72.55, with an average of 71.67 wAl2O2o, 13.6222, 14.5555, with an average of 14.03wK2O2O4.185.285.85. the whole alkali Na2OK2O7.097.89and the average 7.51K / Na2O / Na2O / Na2O ratio 1.444.51a, an average of 2.02; the whole body belongs to iron, and the total Na2OK2O7.097.89and the average 7.51K2O/ Na2O / Na2O / Na2O ratio of 1.444.51, on average 2.02; the total is iron, In the peraluminous granitoids of the high-potassium calc-alkaline-potash series, the baccaluminous granitoids Ba-Nb-Nb-Sr-Pa-Ti show obvious depletion of RbTH (RbThU), and the source rocks are mainly medium and upper crustal metamorphic sandstone (鈭，

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