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首页> 外文期刊>Geologia Croatica: a journal of the Institute of Geology Zagreb and Croatian Geological Society >Geochronology, geochemistry, and tectonic significance of the Shirenshan gneiss in the southern margin of the North China Block
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Geochronology, geochemistry, and tectonic significance of the Shirenshan gneiss in the southern margin of the North China Block

机译：华北地块南缘的狮人山片麻岩的年代学，地球化学及其构造意义

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摘要

The Shirenshan Block is a complex geological body located in the southern margin of the North China Block (NCB). From south to north, it can be divided into the Taihua Group migmatite, and the Shirenshan gneiss and magmatic rocks. The petrographic features, tectonic setting, provenance, and geological age of the Shirenshan gneiss using comprehensive field investigations, microstructural analysis, zircon U-Pb radioactive dating, and geochemical analyses were investigated for this study. The petrology, geochemistry, and geochronology of the Shirenshan gneiss suggests that it is mainly a felsic rock and its protolith was a high-K calc-alkaline series A-type granite. The protolith is high in SiOsub2/sub, Alsub2/subOsub3/sub, Ksub2/subO, Nasub2/subO, and low in CaO and MgO. Overall, the Sr-Nd isotope composition of the samples showed no significant difference, indicating that the Taihua Group migmatite and the Shirenshan gneiss have the same source material. The Shirenshan block may be partially melted from the Taihua group and formed during activity of the Luo-Luan Fault. By the method of zircon dating analysis, the protolith age of the Shirenshan block was determined as 1559±16Ma (Early Proterozoic). Then, the crystallization age of the syntectonic migmatite is 439.2±7.6Ma, which was formed by subduction of the Taihua Group. During the early Cretaceous (119.5±1.3Ma), the Shirenshan gneiss may have experienced regional migmatization and formed the zircon rims age of the Yanshanian period. Litho-geochemical features of the Shirenshan block are similar to A1-type granites indicating that they are post-orogenic. Therefore, the metamorphic deformation of the Shirenshan gneiss reflects the tectonics in the southern margin of the NCB.
机译：石人山区块是一个复杂的地质体，位于华北区块（NCB）的南部边缘。从南到北，可分为泰华族蒙脱石，石人山片麻岩和岩浆岩。通过全面的野外调查，微观结构分析，锆石U-Pb放射性测年和地球化学分析，对石人山片麻岩的岩石学特征，构造背景，物源和地质年龄进行了研究。石人山片麻岩的岩石学，地球化学和年代学表明，它主要是长英质岩石，其原生岩是高钾钙碱性系列A型花岗岩。 SiO 2 ，Al 2 O 3 ，K 2 O，Na 2 O，并且CaO和MgO含量低。总体而言，样品中的Sr-Nd同位素组成无明显差异，表明太化组辉锰矿和石人山片麻岩具有相同的来源。石人山块体可能是太华群的一部分融化，并在罗栾断层活动期间形成。通过锆石测年分析，确定了石人山块体的原生石年龄为1559±16Ma（元古代）。然后，由太华集团俯冲形成的组构辉辉岩的结晶年龄为439.2±7.6Ma。在白垩纪早期（119.5±1.3Ma），石人山片麻岩可能经历了区域性迁移，并形成了燕山时期的锆石轮缘年龄。石人山区块的岩石地球化学特征与A1型花岗岩相似，表明它们是造山后的。因此，石人山片麻岩的变质变形反映了NCB南缘的构造。

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