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Subduction Factory: Its Role in the Evolution of the Solid Earth Y
Subduction Factory: Its Role in the Evolution of the Solid Earth Y.Tatsumi (IFREE, JAMSTEC) ・Outline of subduction factory ・General characteristics of magmatism and basalt genesis ・Andesite genesis and continental crust formation ・Fate of waste materials and mantle evolution
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The Subduction Factory
Raw materials Oceanic material Mantle material Products Magma/Volcanoes Volatiles Continental crust Residues Chemically modified slab Delaminated lower crust
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General Characteristics of Arc Magmatism
・Dual volcanic chains ・Inverse correlation between arc width and subduction angle ・High-T mantle wedge and hot fingers ・Selective enrichment of LIL elements
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Volcano Distribution in NE Japan Arc
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Distance from Volcanic Front vs. Number of Volcanoes
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General Characteristics of Arc Magmatism
・Inverse correlation between arc width and subduction angle ・Dual volcanic chains ・High-T mantle wedge and hot fingers ・Selective enrichment of LIL elements
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Subduction Angle vs. Arc Width
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Constant Depth to Slab Surface
タイトルお願いします。
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Hydrous Phases Stability: Basalt
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Migration of Fluids タイトルお願いします
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Hydrous Phases Stability: Peridotite
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Formation of Hydrous Curtains
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General Characteristics of Arc Magmatism
・Dual volcanic chains ・Inverse correlation between arc width and subduction angle ・High-T mantle wedge and hot fingers ・Selective enrichment of LIL elements
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Generation of Arc Basalt Magmas
Tatsumi et al. (1983)
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Seismic Tomography Image beneath NE Japan
Zhao et al. (1992) タイトルお願いします
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Numerical Simulation Experiments
Furukawa (1993) タイトルお願いします
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Heterogeneous Volcano Distribution in NE Japan Arc
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Heterogeneous Distribution of High-T Mantle Wedge
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Heterogeneous Distribution of High-T Mantle Wedge
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Hot Fingers in the Mantle Wedge
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General Characteristics of Arc Magmatism
・Dual volcanic chains ・Inverse correlation between arc width and subduction angle ・High-T mantle wedge and hot fingers ・Selective enrichment of LIL elements
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Trace Element Characteristics
Subduction zone basalt 配置、順序等はてきとうですのでご指示お願いします。
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Element Transport during Dehydration
Starting Materials Plate-forming hydrous materials such as sediments/amphibolites Being set in a perforated platinum capsule High-P/T Dehydration Experiments Decomposition of starting materials Releasing H2O that dissolves elements Leaving anhydrous residue Chemistry: starting materials vs. residue 配置、順序等はてきとうですのでご指示お願いします。
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Element Transport via. Dehydration
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Inferred Arc Magma Compositions
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Origin of Andesites and Continental Crusts
・Calc-alkalic vs. tholeitic andeistes ・Bulk continental crust: andesitic, not basaltic compositions
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Arc Magmas vs. Continental Crust
TH CA 黄色の部分が最前面なら問題ないのですが、背面におくるため画像の処理をしていますのでちょっと図が粗くなってしまいます。
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Characteristics of Calc-Alkalic Andesites
Rather straight differentiation trend Disequilibrium phenocryst assemblages (e.g., ol+qz) Presence of reversely-zoned phenocryst Bimodal distribution of phenocryst-core compositions Origin of End-member Magmas Basalt magma:mantle-derived Felsic magma:external or internal origin? A Plausible Mechanism: --mixing of basaltic and felsic magmas
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Crustal Origin for Felsic Magmas
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Andesitic Continental Crust Formation
Ancient MORB Ridge Alteration Element Transport Slub Fluid Ancient Altered MORB Ancient Magma Source Ancient Original Mantle Wedge (Primitive Mantle) ancient Primary Basalt Initial Arc Crust Remolten Felsic Magma Continental crust Mixing Primary Basalt Magma Source Original Mantle Wedge (N-MORB Source) Element Transport Slub Fluid Altered MORB Fresh MORB Ridge Alteration
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Inferred Andesites produced by Magma mixing
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Delamination Process Required
Initial Arc Crust Dacite Restite Anatexis/Mixing Basalt Mixing Delamination Andesite Restite Basaltic Comp.
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Fate of Waste Materials
・Oceanic crust (dehydrated and fresh) ・Sediments ・Delaminated anti-continental crust
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Isotopic characteristics of Oceanic Magmas
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Chemical Modification of Altered Oceanic Crust
Element Transport via. Dehydration
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Isotopic Evolution of Sinking Crusts
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Chemical Modification of Subducting Sediments
Element Transport via. Dehydration
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Isotopic Evolution of Sinking Sediments
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Isotopic Evolution of Delaminated Arc Crust
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Material Recycling in the Earth Interior
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The Subduction Factory
Raw materials Oceanic material Mantle material Products Volcanoes Volatiles Continental crust Residues Chemically modified slab Delaminated lower crust
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I F R E E Institute for Frontier Research on Earth Evolution
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