Geochemistry, Metamorphic Evolution and Its Tectonic Implications of Amphibolites in the Southwest Area of the Zanhuang Complex
详细信息
- 责任者：Xiao LingLing (Institute of Geology ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Lu JunSheng
- 刊名：Acta Petrologica Sinica
- 出版年：2012
- 卷期：28(9)
- 关键词：角闪岩 ; amphibolites ; 杂岩 ; complexes ; 岩石地球化学 ; lithogeochemistry ; 河北 ; Hebei Province
- 页码：p.2807-2818
- 图表：6 illus., 2 tables, 45 refs.
- 分类号：0802
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Zanhuang complex is located at the eastern margin of the middle segment of the nearly NS-striking Trans-North China Orogen. Previous studies suggested that the Archaean metamorphic rocks only expose in the middle-southern part of the complex. However, our new research found that (garnet-bearing) amphibolites also exposed in the southwestern part of the complex. Geochemical data indicate that protoliths of these amphibolites were possibly calc-alkaline basaltic rocks and were formed in volcanic arcs, similar to amphibolites in the southeastern part of the complex. The garnets in these rocks record weak chemical zoning, which preserve three different metamorphic mineral assemblages formed during the prograde, peak and retrograde stages. Clockwise P-T paths are thus yielded for the amphibolites, which is characterized by the nearly isothermal decompression (ITD) segments. This suggests that the metamorphism most likely resulted from the collisional process related to the amalgamation of the Eastern and Western blocks to form the coherent Precambrian basement of the North China Craton along the Trans-North China Orogen.