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https://doi.org/10.4154/gc.2019.21

Geochronology, geochemistry, and tectonic significance of the Shirenshan gneiss in the southern margin of the North China Block

Jingya Wang orcid.org/0000-0002-8812-132X ; School of Resources and Environmental Engineering, HeFei University of Technology, Hefei 230009, China
Shenglian Ren orcid.org/0000-0002-8812-132X ; School of Resources and Environmental Engineering, HeFei University of Technology，Hefei 230009，China
Shuwen Dong orcid.org/0000-0002-8812-132X ; School of Geoscience and Engineering, Nanjing University，Nanjing 230026，China
Li Longming orcid.org/0000-0002-8812-132X ; School of Resources and Environmental Engineering, HeFei University of Technology, Hefei 230009, China
Dazhi Jiang orcid.org/0000-0002-8812-132X ; School of Earth Sciences, Western University，London，Ontario N6A 3K7，Canada
Yonghong Shi ; School of Resources and Environmental Engineering, HeFei University of Technology，Hefei 230009，China
Jiahao Li ; School of Resources and Environmental Engineering, HeFei University of Technology，Hefei 230009，China
Chuanzhong Song ; School of Resources and Environmental Engineering, HeFei University of Technology，Hefei 230009，China
Xu Han ; School of Resources and Environmental Engineering, HeFei University of Technology，Hefei 230009，China
Zhenqiang Li ; School of Resources and Environmental Engineering, HeFei University of Technology，Hefei 230009，China
Jue Ouyang ; School of Resources and Environmental Engineering, HeFei University of Technology，Hefei 230009，China

Abstract

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 SiO₂, Al₂O₃, K₂O, Na₂O, 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.

Keywords

Hrčak ID:

232021

URI

https://hrcak.srce.hr/232021

Publication date:

17.12.2019.

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