Petrology of peridotite xenolith-bearing basaltic to andesitic lavas from the Shiribeshi Seamount, off northwestern Hokkaido, the Sea of Japan

作者：Ichiyama Yuji^*; Morishita Tomoaki; Tamura Akihiro; Arai Shoji

来源：Journal of Asian Earth Sciences, 2013, 76: 48-58.

DOI：10.1016/j.jseaes.2013.07.031

• Shiribeshi Seamount
• Rear-arc volcano
• Mantle xenolith
• Magma mixing
• Magma-peridotite xenolith reaction

The Shiribeshi Seamount off northwestern Hokkaido, the Sea of Japan, is a rear-arc volcano in the Northeast Japan arc. This seamount is composed of calc-alkaline and high-K basaltic to andesitic lavas containing magnesian olivine phenocrysts and mantle peridotite xenoliths. Petrographic and geochemical characteristics of the andesite lavas indicate evidence for the reaction with the mantle peridotite xenoliths and magma mixing between mafic and felsic magmas. Geochemical modelling shows that the felsic end-member was possibly derived from melting of an amphibolitic mafic crust. Chemical compositions of the olivine phenocrysts and their chromian spinet inclusions indicate that the Shiribeshi Seamount basalts in this study was derived from a primary magma in equilibrium with relatively fertile mantle peridotites, which possibly represents the mafic end-member of the magma mixing. Trace-element and REE data indicate that the basalts were produced by low degree of partial melting of garnet-bearing lherzolitic source. Preliminary results from the mantle peridotite xenoliths indicate that they were probably originated from the mantle beneath the Sea of Japan rather than beneath the Northeast Japan arc.

• 出版日期2013-10-25