北京西山南窖地区南东东110°～120°拉伸线理形成时间的年代学制约  

Thermochronological constraints on the formation of ESE110°～120°stretching lineations at Nanjiao area,West Hills of Beijing.

作　　者：王瑜[1] 李锦轶[2] 

机构地区：[1]中国地质大学(北京)地学实验中心,北京100083 [2]中国地质科学院地质研究所,北京100036

出　　处：《岩石学报》2007年第3期617-624,共8页Acta Petrologica Sinica

基　　金：中国教育部优秀人才支持计划项目(2005年度);国家自然科学基金重点项目(40132020)

摘　　要：本文简要报导位于北京西山房山岩体以西约15km左右的南窖闪长岩脉形成的锆石U-Pb年龄,以及区内变形岩层中同变形的白云母和绢云母矿物的^(40)Ar/^(39)Ar年龄。在野外构造研究、室内岩石及显微构造分析基础上,获得细粒闪长岩岩脉锆石U-Pb年龄为136±1Ma,并且该岩脉受到后期构造片理化的改造。区内变形岩层中所发育的南东东110°～120°矿物拉伸线理及相关的"褶叠层"中同变形的白云母、绢云母的^(40)Ar/^(39)Ar坪年龄为133±1～127±1Ma。显然这些变形并非形成于三叠纪或"印支期",而是形成于大规模的向北西方向强烈的挤压变形之后,与相邻区域的岩浆热作用同期或稍晚。这些构造-热年代学证据对于区内构造格局的形成与演化是一个重要的约束。In the west Hills of Beijing, structural stages are very complicated, but one of the most important constraints is the timing of the ESE110°～120°stretching lineations and correlated dioritic dykes. Based on the detailed field study, macro- and micro-structure analysis, this paper reports zircon U-Pb ages of the Nanjiao dioritic dykes, syn-deformation muscovite and sericite ^40Ar/^39Ar plateau ages for the deformed strata surrounding the dykes. Zircon U-Pb age is 136±1Ma, and the dated dioritic dyke has been schistosed during the later deformation. The muscovite and sericite minerals aligned parallel to the ESE110°～120°stretching lineations and yielded ^40Ar/^39Ar plateau ages of 133 - 127Ma. It can be suggested that the formation of the dioritc dyke and stretching lineations was not developed during the Triassic time, instead, they were formed after the extensive NW-oriented contraction, and syn- or slightly post to the local granitic intrusions. Based on the structural features and tectono-thermochronological evidence, the structural stages and tectonic evolution in the west Hills of Beijing and adjacent regions should be re-considered.

关 键 词：北京西山 U-Pb和Ar/Ar热年代学 拉伸线理 闪长岩脉 构造演化 

分 类 号：P597.3[天文地球—地球化学] P542.3[天文地球—地质学]