辽南三家子地区南辽河群里尔峪组变沉积岩中碎屑锆石U-Pb年代学研究

发布时间：2018-07-10 17:49

本文选题：锆石U-Pb年龄 + 变沉积岩　；参考：《岩石学报》2017年09期

【摘要】：南辽河群里尔峪组主要分布在华北克拉通胶-辽-吉活动带的大石桥-岫岩-凤城-宽甸一带,主要岩性为各类长英质粒状岩石(浅粒岩-变粒岩组合)。通过前人长期深入研究,在区域构造、地球化学、同位素年代学研究、变质作用以及构造演化等方面积累了大量资料,取得了一系列重要进展。但是,有关其变质作用特征、沉积时代、源区特征以及辽河群乃至整个胶-辽-吉活动带的大地构造属性和形成的构造演化过程长期以来存在着裂谷开启-闭合模式、弧-陆碰撞模式和陆-陆碰撞模式的争论。本文在辽南地区1∶5万变质岩区专题填图的基础上,选择三家子地区南辽河群里尔峪组的疙瘩状长英质粒状岩石、黑云斜长片麻岩和含黑云母长英质粒状岩石为重点研究对象。通过锆石阴极发光图像特征和锆石LA-ICP-MS U-Pb年代学测试,综合限定研究区南辽河群里尔峪组变质沉积岩的物质来源和原岩形成时代,进而探讨其形成的构造背景。3件样品中锆石阴极发光图像显示核-边结构,核部具振荡环带,Th/U比值较高(Th/U=0.12~4.95),表明其岩浆来源;U-Pb年代学测试分别得到2140Ma、2170Ma和2150Ma的年龄峰值。综合前期研究成果,锆石U-Pb年代学测试结果在年龄直方图中显示明显的2137Ma的峰值。该组年龄与区域上大量出露的辽吉花岗岩的年龄具有一致性,表明南辽河群里尔峪组的物质来源于辽吉花岗岩,其沉积时限应晚于古元古代。
[Abstract]:The Lianyu formation of the South Liaohe Group is mainly distributed in the Dashiqiao Xiuyan Fengcheng Kuandian area of the North China Craton Jiaoliao Liaoji active belt. The main lithology is felsic granular rock (shallow-granulite-granulite assemblage). Through a long period of in-depth studies by predecessors, a great deal of data have been accumulated in regional tectonics, geochemistry, isotopic chronology, metamorphism and tectonic evolution, and a series of important advances have been made. However, the characteristics of metamorphism, sedimentary epoch, source area, tectonic attributes of Liaohe Group and even the whole Jiao-Liaojia-Ji active belt, and the tectonic evolution process of formation have long existed rift opening and closing mode. Arc-land collision model and land-land collision model are controversial. Based on the topographic mapping of the 1: 50 000 metamorphic rock area in southern Liaoning Province, this paper selects the keloid felsic granulated rocks of the Liliyu formation of the South Liaohe Group in Sanjiazi area. The study of biotite-feldspar granulite and biotite-bearing feldspar granulite is the main research object. Based on the characteristics of zircon cathodoluminescence images and zircon LA-ICP-MS U-Pb geochronology, the material source and the age of origin of the metamorphic sedimentary rocks in the Liliyu formation of the South Liaohe Group in the study area are comprehensively limited. Furthermore, the zircon cathodoluminescence images of the 3 samples formed in the tectonic setting show a nucleus-edge structure with a high Th-P / U ratio of the oscillatory ring zone (Th/ UU 0.12U 4.95), indicating that the dating peaks of 2140 Ma, 2170 Ma and 2150 Ma are obtained from the U-Pb geochronological measurements of their magma origin, respectively. Combined with the previous results, the zircon U-Pb dating results show an obvious peak value of 2137 Ma in the age histogram. The age of this group is consistent with that of the Liaoji granite, which indicates that the material of the Lianyu formation of the South Liaohe Group originates from the Liaoji granite, and its sedimentary time is later than that of the ancient Gu Yuan.
【作者单位】：中国地质科学院地质研究所;
【基金】：国家自然科学基金重点项目(41430210) 中国地质调查局项目(DD20160121) 中国地质科学院基本科研业务费项目(YYWF201703、J1614)联合资助
【分类号】：P588.3;P597.3

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