Mineralogical and geochemical patterns of mantle xenoliths from the Jixia region (Fujian Province, southeastern China)

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• 作者：G. S. Zhang ; A. V. Bobrov ; J. S. Long ; W. H. Han
• 关键词：spinel peridotite ; lithospheric mantle ; mantle xenoliths ; clinopyroxene megacrysts ; southeastern China
• 刊名：Geochemistry International
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：54
• 期：10
• 页码：901-913
• 全文大小：2,058 KB
• 刊物主题：Geochemistry;
• 出版者：Springer US
• ISSN：1556-1968
• 卷排序：54

文摘

The paper discusses the results of mineralogical and petrographic studies of spinel lherzolite xenoliths and clinopyroxene megacrysts in basalt from the Jixia region related to the central zone of Cenozoic basaltic magmatism of southeastern China. Spinel lherzolite is predominantly composed of olivine (Fo_89.6–90.4), orthopyroxene (Mg# = 90.6–92.7), clinopyroxene (Mg# = 90.3–91.9), and chrome spinel (Cr# = 6.59–14.0). According to the geochemical characteristics, basalt of the Jixia region is similar to OIB with asthenospheric material as a source. The following equilibrium temperatures and pressures were obtained for spinel peridotite: 890–1269°C and 10.4–14.8 kbar. Mg# of olivine and Cr# of chrome spinel are close to the values in rocks of the enriched mantle. It is evident from analysis of the textural peculiarities of spinel lherzolite that basaltic melt interacted with mantle rocks at the xenolith capture stage. Based on an analysis of the P–T conditions of the formation of spinel peridotite and clinopyroxene megacrysts, we show that mantle xenoliths were captured in the course of basaltic magma intrusion at a significantly lower depth than the area of partial melting. However, capture of mantle xenoliths was preceded by low-degree partial melting at an earlier stage.