Details

Autor(en) / Beteiligte

• Huang, Xiao-Wen
• Su, Ben-Xun
• Zhou, Mei-Fu
• Gao, Jian-Feng
• Qi, Liang

Titel

Cenozoic basalts in SE China: Chalcophile element geochemistry, sulfide saturation history, and source heterogeneity

Ist Teil von

• Lithos, 2017-06, Vol.282-283, p.215-227

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2017

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Cenozoic basalts in SE China may be derived from a mixture of depleted MORB mantle (DMM) and enriched mantle 2 (EM2) sources, but whether these basalts share a common mantle source or magmatic history remains unknown. To investigate these unresolved issues, this study sampled basalts from Niutoushan and Mingxi (Fujian province), Xilong (Zhejiang province), and Penghu (Taiwan) for geochemical analysis. The basalt samples show OIB-like trace element patterns and have low PGE contents, with 0.02–0.7ppb Ir and Pd, 0.05–1.4ppb Ru, 0.01–0.2ppb Rh, and 0.06–1.1ppb Pt. All samples have high Cu/Pd ratios ranging from ~69,000 to 3,500,000, and low Cu/Zr ratios ranging from 0.1 to 0.8, suggesting sulfur-saturated fractionation. Model calculations indicate that the basalts are depleted in PGE due to the retention of 0.001% to 0.1% sulfide in the mantle and the removal of up to 0.0022% sulfide during magma ascent. The crystallization of olivine and spinel, and partial melting are insufficient to account for the observed PGE variation in these basalts. Thus, the distinct PGE patterns in basalts with different ages may reflect the heterogeneity of the mantle source beneath SE China. The source heterogeneity may be due to compositional heterogeneity, particularly variations in oxygen fugacity and PGE mineral phases, or due to variable fluid/melt metasomatic agents in the sub-continental lithospheric mantle. This heterogeneity is possibly related to the westward subduction of the Paleo-Pacific Plate. •Basalts from SE China are PGE-depleted due to S-saturation fractionation.•Variable sulfides remained in the mantle and sulfide removed during magma ascent.•Fractional crystallization and partial melting are insufficient to explain PGE variations.•Mantle heterogeneity may be due to different oxygen fugacities of the mantle source.•Variable fluid/melt metasomatism in the SCLM may also induce the heterogeneity.