Geochemical Characteristics and Tectonic Implications of the early Permian Volcanic Rocks from Ongniud Banner, Inner Mongolia

Abstract:

The Early Permian volcanic-sedimentary sequences of Ongniud Banner consist mainly of andesite, rhyolite, perlite, volcanic breccia, tuff, tuffaceous sandstone, siliceous rock. Rock assemblage and sedimentary formations indicate that are of fore-arc basin sedimentary feature between subduction zone and island arc in Early Permian. The volcanic rocks from Elitu Formation have SiO₂=50.23%~74.83%, Mg^#=6.21~49.54, Na₂O+K₂O=5.27%~10.73%, Na₂O/K₂O=0.36~4.17, belonging to high-K cal-alkaline (HKCA)~shoshonite (SHO) series. The volcanic rocks are characterized with (La/Yb)_N=5.52~9.89, moderate - intense negative Eu anomalies, LILE enrichment such as Ba, Ra, K, Th and HFSE depletion such as Ta, Nb, P, Ti, and indicating that magma could be formed in the tectonic setting of the island arc and active continental margin related to the plate subduction. R1-R2 diagram also indicates that volcanic rocks were generated at syn-collision or post-orogenic period, perhaps representing the mid-later subduction stage of the Palaeo-Asian Ocean Plate and North China Plate. Taken together, the authors suggest that the region was located still in the Palaeo-Asian Ocean, rather than the intracontinental taphrogenic trough in Early Permian.

• Periodical: Advanced Materials Research (Volumes 734-737)
• Pages: 344-351
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.734-737.344
• Online since: August 2013
• Authors: Deng Liu, Dai Yong Cao, Yi Wu Wang, Zhong Yuan Liu
• Keywords: Early Permian, Elitu Formation, Geochemistry, Inner Mongolia, Ongniud Banner, Tectonic Setting, Volcanic Rock

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