E the system will be hotter if isotherms a the

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Unformatted text preview: ter) if Isotherms a) the convergence rate is slower a) the b) the subducted slab is young and near the ridge (warmer) c) the arc is young (<50-100 Ma according to Peacock, 1991) yellow curves = mantle flow mantle Figure 16-15. Cross section of a subduction zone showing isotherms (red-after Furukawa, 1993, J. Geophys. Res., 98, 83098319) and mantle flow lines (yellow- after Tatsumi and Eggins, 1995, Subduction Zone Magmatism. Blackwell. Oxford). The principal source components → IA magmas 1. The crustal portion of the subducted slab crustal subducted 1a Altered oceanic crust (hydrated by circulating seawater, and metamorphosed in large part to greenschist facies) and 1b Subducted oceanic and forearc sediments 1c Seawater trapped in pore spaces Figure 16-15. Cross section of a subduction zone showing isotherms (red-after Furukawa, 1993, J. Geophys. Res., 98, 83098319) and mantle flow lines (yellow- after Tatsumi and Eggins, 1995, Subduction Zone Magmatism. Blackwell. Oxford). The principal source components → IA magmas The 2. The mantle wedge between the slab and the arc crust 2. mantle 3. The arc crust arc 4. The lithospheric mantle of the subducting plate lithospheric 5. The asthenosphere beneath the slab asthenosphere Figure 16-15. Cross section of a subduction zone showing isotherms (red-after Furukawa, 1993, J. Geophys. Res., 98, 83098319) and mantle flow lines (yellow- after Tatsumi and Eggins, 1995, Subduction Zone Magmatism. Blackwell. Oxford). q q Left with the subducted crust and mantle wedge Left subducted mantle The trace element and isotopic data suggest that both The both contribute to arc magmatism. How, and to what extent? extent? 3 Dry peridotite solidus too high for melting of anhydrous mantle to occur anywhere in the thermal regime shown thermal 3 LIL/HFS ratios of arc magmas → water plays a LIL/HFS water significant role in arc magmatism significant q The sequence of pressures and temperatures that a rock is The subjected to during an interval such as burial, subduction, metamorphism, uplift, etc. is called a pressure-te...
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This note was uploaded on 04/13/2013 for the course GEO 124 taught by Professor Yusuf during the Spring '13 term at Ankara Üniversitesi.

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