Hou, G., Yao, W., Yang, M., Yi, X., Wang, C. and Wang, Y. 2006.   Geochemical constraints on the tectonic environment of ~1.8 Ga mafic dyke swarms in the North China Craton. In: (Ed.) Guiting Hou, and Jianghai Li, Precambrian Geology of the North China Craton, Journal of the Virtual Explorer, Electronic Edition, ISSN 1441-8142, volume 24, paper 10, doi:10.3809/jvirtex.2006.00159

Geochemical constraints on the tectonic environment of ~1.8 Ga mafic dyke swarms in the North China Craton

Guiting Hou

The Key Laboratory of Orogenic Belts and Crustal Evolution, Tectonophysic Simulation Group, Beijing, China,

School of Earth and Space Sciences, Peking University, Beijing 100871, China

<gthou@pku.edu.cn>

Weihao Yao

The Key Laboratory of Orogenic Belts and Crustal Evolution, Tectonophysic Simulation Group, Beijing, China,

School of Earth and Space Sciences, Peking University, Beijing 100871, China

Mohan Yang

The Key Laboratory of Orogenic Belts and Crustal Evolution, Tectonophysic Simulation Group, Beijing, China,

School of Earth and Space Sciences, Peking University, Beijing 100871, China

Xuelei Yi

The Key Laboratory of Orogenic Belts and Crustal Evolution, Tectonophysic Simulation Group, Beijing, China,

School of Earth and Space Sciences, Peking University, Beijing 100871, China

Chuancheng Wang

The Key Laboratory of Orogenic Belts and Crustal Evolution, Tectonophysic Simulation Group, Beijing, China,

School of Earth and Space Sciences, Peking University, Beijing 100871, China

Yanxin Wang

The Key Laboratory of Orogenic Belts and Crustal Evolution, Tectonophysic Simulation Group, Beijing, China,

School of Earth and Space Sciences, Peking University, Beijing 100871, China

Abstract

Late Paleoproterozoic mafic dyke swarms are widespread in Shandong Province in the Eastern Block and in Shanxi Province in the Western Block and Central Orogenic Zone of the North China Craton (NCC). Both of the mafic dyke swarms plot mainly in the field of intra-plate basalts and are related to an intra-plate rift environment. The trace element spidergrams and the rare-earth element (REE) graphs of both mafic dyke swarms show similar geochemical features to data from the lavas in the Yanliao and Zhongtiao aulacogens. This suggests that the magma source of the mafic dyke swarms is related to the aulacogens. The trace elements and isotopica data from the mafic dykes and lavas in the aulacogens pior between OIB and Lower Crust. Enriched LREEs result from contamination by the interaction between a mantle plume and the lower crust.

The mantle plume supplied heat to partially melt lower crust and produce enriched magma. The mafic dyke swarms in Shandong and Shanxi Provinces are thus derived from the same magma source and are related to plume activity in the same intra-plate rift environment.

Keywords: Mafic dyke swarms, Late Paleoproterozoic, Mantle plume, Yanliao and Zhongtiao aulacogens, North China Craton

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