In:
Geological Journal, Wiley, Vol. 48, No. 5 ( 2013-09), p. 516-530
Abstract:
Cretaceous dyke swarms are widespread in the Guocheng fault belt, Jiaodong Peninsula, eastern North China Craton (NCC). Elemental analyses show that these dykes are classified as high‐K calc‐alkaline to shoshonitic series, and are characterized by high MgO (up to 10.33 wt%; Mg # 〈 69.8), Cr ( 〈 571 ppm) and Ni ( 〈 235 ppm) at low silica contents. They are enriched in LILEs (e.g. Sr, Ba, K and Pb) and LREEs, depleted in HFSEs (e.g. Nb–Ta, Zr–Hf, Ti and P), and possess relatively radiogenic Sr (initial 87 Sr/ 86 Sr = 0.7078 to 0.7116) and Nd [ ε Nd ( t ) = −20.8 to −13.5] and much less radiogenic Pb ( 206 Pb/ 204 Pb = 17.13 to 17.56) isotope signatures. These data, combined with inversely zoned amphibole and pyroxene phenocrysts, suggest a hybrid origin for the Guocheng dykes. The inferred magma evolution is dominated by repeated injection of basic magma from metasomatized subcontinental lithospheric mantle (SCLM) into a lower crustal reservoir of intermediate‐felsic composition. This refertilized lithospheric mantle source, probably together with its overlying enriched lower crust, was formed by subduction‐related fluid metasomatism in the Palaeoproterozoic, which resulted from final cratonization of the NCC at ca . 1.8 Ga during assembly of Columbia supercontinent. Our observations also imply that similar mixed magma system with oxidized and sulphur‐rich signatures may be the key to the formation of hydrothermal polymetal deposits and the potential target for mineral exploration in some undiscovered areas. Copyright © 2012 John Wiley & Sons, Ltd.
Type of Medium:
Online Resource
ISSN:
0072-1050
,
1099-1034
Language:
English
Publisher:
Wiley
Publication Date:
2013
detail.hit.zdb_id:
1479201-1
SSG:
13
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