Origin of dyke swarms by mixing of metasomatized subcontinental lithospheric mantle‐derived and lower crustal magmas in the Guocheng fault belt, Jiaodong Peninsula, North China Craton

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 87Sr/86Sr = 0.7078 to 0.7116) and Nd [εNd(t) = −20.8 to −13.5] and much less radiogenic Pb (206Pb/204Pb = 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.

Geochronological framework of the Damoqujia gold deposit, Jiaodong Peninsula, China: Implications for the timing and geologic setting of gold mineralization

“…Similarly, zircon dating of lamprophyre and gabbro‐diorite in the Damoqujia deposit produced 206 Pb/ 238 U concordia ages of 125 ± 1 (Figure d, MSWD = 2.60, Probability = 0.11) and 120 ± 1 Ma (Figure d, MSWD = 1.60, Probability = 0.20), respectively. Previous studies imply multiple sources for these dykes from convective asthenospheric mantle to ancient enriched lithospheric mantle with magma generation at different depths (L. Li et al, ; S. Liu et al, ; L. Ma, Jiang, Hou, et al, ; L. Ma, Jiang, Hofmann, et al, ; Tan et al, ; J. H. Yang, Chung, Zhai, & Zhou, ).…”

Tectonic Settings of Potassic Igneous Rocks

“…From Müller et al (1992a) et al 2014; Liu et al 2014;Wang et al 2014;Aghazadeh et al 2015). However, there is a general consensus that potassic magmas cannot be derived by partial melting of normal mantle peridotite, but require heterogeneous mantle sources which have been metasomatically enriched in LILE and LREE (Edgar 1987;Foley and Peccerillo 1992;Guo et al 2013;Kuritani et al 2013;Tan et al 2013b;Bucholz et al 2014;Aghazadeh et al 2015;Yang et al 2015).…”

Occurrence Mechanism of Convective Geothermal Systems in Jiaodong Peninsula, China

“…There was no obvious mixing of crustal material during their ascent. They originated from the lithospheric mantle rather than the asthenosphere mantle (Tan et al, 2006).…”