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Primitive magmas in the Emeishan Large Igneous Province, southwestern China and northern Vietnam

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Hanski, E and Kamenetsky, VS and Luo, ZY and Xu, YG and Kuzmin, DV (2010) Primitive magmas in the Emeishan Large Igneous Province, southwestern China and northern Vietnam. Lithos, 119 (1-2). pp. 75-90. ISSN 0024-4937

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Abstract

There are several places in the Emeishan Large Igneous Province (ELIP) where highly magnesian volcanic or intrusive rocks accompany more abundant flood basalts. The high-Mg rocks vary in composition from LREE-depleted, low-Ti komatiites to LREE-enriched, high-Ti picrites. These magmas carried cognate olivine phenocrysts with Fo content higher than 91 mol% indicating that these olivines crystallized and equilibrated with high-Mg melts. The maximum measured Fo content from the Dali area is 93.5 mol% which, depending on the KD value used, indicates a MgO content of 23–25 wt.% for the parental melt. The high estimated MgO wt.% values provide evidence for a hot portion of the Emeishan mantle-plume head with a potential mantle temperature of ca. 1700 °C. Melt inclusions trapped within olivine phenocrysts have compositions similar to those of the host lavas but with a higher variability in the abundance of incompatible trace elements. The inclusions yield a calculated maximum MgO content of ca. 22 wt.% for the melt. The compositional and isotopic variability of the high-Mg magmas in the ELIP is akin to that observed in basaltic rocks, which are divided into low-Ti and high-Ti types, suggesting that most of the basalts were developed in deep crustal magma chambers by fractional crystallization and mixing processes from primitive magmas.

Item Type: Article
Keywords: Picrite Komatiite Olivine Melt inclusion Permian Emeishan China
Journal or Publication Title: Lithos
Page Range: pp. 75-90
ISSN: 0024-4937
Identification Number - DOI: 10.1016/j.lithos.2010.04.008
Additional Information: The definitive version is available at http://www.sciencedirect.com
Date Deposited: 15 Oct 2010 05:04
Last Modified: 18 Nov 2014 04:13
URI: http://eprints.utas.edu.au/id/eprint/10222
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