Melt inclusions of peridotites in Weizbou Island, Northern Bay: New evidence of mantle metasomatism in subcontinentle lithospheric mantle.

作者：Fan QiCheng^*; Sui JianLi; Sun Qian; Li Ni; Zhao YongWei; Du XingXing

来源：Acta Petrologica Sinica, 2008, 24(11): 2495-2500.

• Melt inclusion
• Peridotite xenolith
• Mantle metasomatism
• Subcontinental lithospheric mantle
• Weizhou Island
• Northern Bays

Peridotite xeonliths and enclosed melt inclusions (MIs) record information of geodynamic evolution of subcontinental lithospheric mantle. Small xenoliths, mainly spinet lherzolites in size of several pin, were discovered in the late Pleistocene basalts in Weizhou Island, Northern Bay. Mineral geochemistry indicates that the xenoliths are segments of the lithospheric mantle from 40km 50 km depth. Two types of MIs, high-silicon MIs(64% similar to 68%)and low-silicon(49% similar to 57%) MIs, occur in the peridotites, and both types of the MIs Eire eventually rich in SiO(2), Al(2)O(3), H(2)O, CO(2) and other volatile (2% similar to 5%). Our research indicates that the origins of the MIs are different. High-silicon MIs are. derived from the reaction of basaltic magma from upwelling asthenosphere with orthopyroxene, or partial melting of recycled lower crust into the upper mantle. Low-silicon MIs Eire derived from metasomatism, and the reaction can be described as, high-silicon melts + Olivine -> Opx + low-silicon melts. This reaction consumes SiO(2) and olivine, produces orthopyroxene. The facts provide evidences of the occurrence and diversity of metasomatism reactions between fluid (melt) and peridotite in the subcontinental lithosphere, and also provide a new case of diversity of melt inclusions.

• 出版日期2008-11
• 单位中国地震局