There has been much recent interest in the origin of intermediate lava and several hypotheses are: 1) direct melting of the mantle under water-saturated conditions, 2) partial melting of altered crust, 3) fractional c...There has been much recent interest in the origin of intermediate lava and several hypotheses are: 1) direct melting of the mantle under water-saturated conditions, 2) partial melting of altered crust, 3) fractional crystallization of parent magma, and 4) magma mixing of mafic magmas with dacitic/rhyolitic magmas. Volcanic rocks series ranging from basaltic andesite to dacite(SiO_2 ranges from 53.8 to 63.0 wt.%) from the eastern Manus Basin were detected for major and trace element compositions to understand their origin. Low H_2O contents, positive correlations of La-SiO_2 and Yb-SiO_2, oxygen isotope data and the indistinct change of trace element concentrations in oscillatory zoning of plagioclase phenocrysts rule out the models in which silicic lava results from direct melting of hydrous mantle, partial melting of altered oceanic crust or gabbros, and magma mixing, respectively. Besides, the geochemical data of whole rock and melt inclusions indicate that fractional crystallization plays a dominant role in generating the intermediate lava with subduction features.展开更多
基金supported by the National Key Basic Research Program of China (No. 2013CB429700)the National Natural Science Foundation of China (Nos. 4132 5021, 41306053, 40476044)+8 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (No XDA11030302)the Special Fund for the Taishan Scholar Program of Shandong Province (No. ts201511061)the AoShan Talents Program Supported by Qingdao Nationa Laboratory for Marine Science and Technology (No. 2015 ASTP-0S17)the Innovative Talent Promotion Program (No. 2012RA2191)the Science and Technology Devel opment Program of Shandong Province (No. 2013GRC 31502)the Scientific and Technological Innovation Project Financially Supported by Qingdao National Labora tory for Marine Science and Technology (No. 2015ASKJ 03)the National High Level Talent Special Support Programthe CAS/SAFEA International Partnership Program for Creative Research Teamsthe Qingdao Collaborative Innovation Center of Marine Science and Technology
文摘There has been much recent interest in the origin of intermediate lava and several hypotheses are: 1) direct melting of the mantle under water-saturated conditions, 2) partial melting of altered crust, 3) fractional crystallization of parent magma, and 4) magma mixing of mafic magmas with dacitic/rhyolitic magmas. Volcanic rocks series ranging from basaltic andesite to dacite(SiO_2 ranges from 53.8 to 63.0 wt.%) from the eastern Manus Basin were detected for major and trace element compositions to understand their origin. Low H_2O contents, positive correlations of La-SiO_2 and Yb-SiO_2, oxygen isotope data and the indistinct change of trace element concentrations in oscillatory zoning of plagioclase phenocrysts rule out the models in which silicic lava results from direct melting of hydrous mantle, partial melting of altered oceanic crust or gabbros, and magma mixing, respectively. Besides, the geochemical data of whole rock and melt inclusions indicate that fractional crystallization plays a dominant role in generating the intermediate lava with subduction features.
