Methane-rich fluid inclusions from ophiolitic dunite and post-coilisional mafic-ultramafic intrusion:the mantle dynamics underneath the Palaeo-Asian Ocean through to the post-eollisional period
会议名称：《中国科学院地质与地球物理研究所2006学术年会》
会议日期：2007年
学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学]
关 键 词：CH4-H2O+N2 fluid inclusion dunite mafic-ultramafic intrusion redox melting Palaeo-Asian Ocean
摘 要：The protracted development history of the Palaeo-Asian Ocean starting from～1000 Ma to～320 Ma,and continuation of mantle-derived magmatism right through the post-collisional period as manifested by the widespread mafic-ultramafic intrusion and alkaline-peralkaline granite suggest a vigorous,long-running mantle *** the micro-laser Raman spectrometer,we analyzed olivine- and plagioclase-hosted fluid inclusions from ophiolitic dunite,Kudi of the western Kunlun Range,and post-collisional mafic-ultramafic intrusions of the Xiangshan and the Huangshandong,eastern Chinese Tienshan *** results show that fluids brought from the mantle by these rocks are rich in HO and CH with variable amounts of *** of the redox state,pressure and depth of formation for the melt-CH-HO+N fluid systems from the 3 rock suites of the Xinjiang,and comparison of these parameters with those of the peridotite-fluid parageneses for the sub-cratonic upper mantle give meaningful *** fluids were formed in the asthenosphere,were originally CH-N-rich,primordial mantle fluid,but have been progressively diluted with HO and become oxidized by repeated subduction of oceanic *** propose that repeated redox melting in the mantle due to dilution of CH with HO and oxidation caused formation of the long-lived Palaeo-Asian Ocean,brought about extensive intrusion of mafic-ultramafic complexes and alkaline-peralkaline granites right through the post-collisional period,and,consequently,resulted in significant Phanerozoic continental growth in the Central Asian Orogenic *** of atmospheric O and the Earth’s major oxidation occurred at about 2.4 to 2.2 *** of the Earth’s mantle promoted the mantle melting and magma input to the crust,resulting in major continental growth after 2.5 ***,much-postponed oxidation of the primordial mantle underneath the Central Asian Orogenic Belt led to significant continental growth in the Phanerozoic times.