The genesis of Archean supracrustal rocks in the western Shandong Province of North China Craton: Constraints on regional crustal evolution
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- 作者：Wei Wang ; MingGuo Zhai ; M. Santosh
- 刊名：Science China Earth Sciences
- 出版年：2016
- 出版时间：August 2016
- 年：2016
- 卷：59
- 期：8
- 页码：1583-1596
- 全文大小：4,574 KB
- 刊物主题：Earth Sciences, general;
- 出版者：Springer Berlin Heidelberg
- ISSN：1869-1897
- 卷排序：59
文摘
Archean greenstone belts are supracrustal sequences, the lower part of which is usually composed of voluminous ultramafic-mafic volcanics. Intermediate and acid volcanic rocks increase in abundance towards the upper domains. Greenstone belts constitute ~30% of the total volume of Archean cratons, and preserve significant information on the surface environment and magmatism in the early earth, which are useful in unraveling the nature of crustal formation and evolution. The western Shandong Province (WSP) is located at the eastern part of the North China Craton (NCC), where greenstone sequences formed at ~2.7 and ~2.5 Ga were well preserved. The early Neoarchean supracrustal rocks include komatiite-basalt sequence, some meta-sediments of the lower part of the Taishan Group and the Mengjiatun Formation. The volcanism had been correlated to mantle plume, which resulted in vertical crustal accretion. The late Neoarchean supracrustal rocks were composed of metamorphosed felsic volcano-sedimentary sequences and BIFs of the upper part of the Taishan Group and the Jining Group. The geochemical features of the meta-volcanics show calc-alkaline affinities, similar to modern arc-related magmatism, suggesting that the continental crust in the western Shandong Province witnessed horizontal plate movements at ~2.5 Ga. The metasediments and leucosomes in the Qixingtai area display regional upper amphibolite facies metamorphism and anatexis at 2.53–2.50 Ga, coeval with formation of large volumes of crustally-derived granites. These tectono-thermal events suggest that a unified continental crust was formed in the western Shandong Province at the end of Neoarchean.KeywordsSupracrustal rocksGreenstone beltsTaishan GroupWestern Shandong ProvinceNorth China Craton