AYBE- Katı Yer Bilimleri Lisansüstü Programı - Yüksek Lisans
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ÖgeSubduction Roll Back and the Generation of Wet and Decompression Melting(Eurasia Institute of Earth Sciences, 2019-05-03) Şen, Mehmet Barış ; Göğüş, Oğuz Hakan ; 602171007 ; Solid Earth Sciences ; Katı Yer Bilimleri Anabilim DalıSubduction zones are the major element of active tectonics (55.000 km) of planet Eart (Stern, 2002). Subduction zones are regions of the Earth affected by the sinking of relatively cold and dense oceanic lithospheres into the mantle. Geophysical and geological evidences have led to interpretation of oceanic lithosphere subduction beneath the Sunda and Japan subduction region. Active subduction is taking important role to creation of serial volcanic province. These volcanic areas show variable chemical properties such as alkaline and calc-alkaline compositions. Alkaline composition is related with low pressure conditions and common at ridge regions however they are observed at some subduction zones such as Sunda arc. Calc-alkaline magmatism is related with dehydration reactions at subduction slab. Volatiles inside the top of the subducted oceanic lithosphere are releasing at 80 - 200 km depth condition. Volatiles decrease the melting temperature and cause partial melt of mantle wedge (triangular asthenospheric window beneath the volcanic arc). Thickness of the subducting slab is changing with oceanic lithosphere age. Feature of the subduction is dominated by thickness of the slab which is changing with age. Numerous 2D numerical geodynamic experiments (I2ELVIS) in the context of the tectonic evolution of the region are conducted to test the effects of the oceanic lithosphere age on melt generation. Within the scope of the models, the age of the oceanic lithosphere has been tried by increasing the age from 50 million to 120 million years. The plate convergence rate was defined as 4 cm / year and 8 cm/yr. The model boundaries are 1400 km vertical and 4000 km horizontal. as defined. The geology of the layers used in the models is defined as follows; 10 km atmosphere, 2 km. ocean, 20 km. felsic upper continental crust (wet quartzite), 15 km. felsic lower crust (wet kurtzite), 3 km. upper oceanic crust (basalt), 5 km. lower oceanic crust (gabbro) and 2 km. width is used for the zone of weakness hydrated mantle. Model result for subduction are comparable with observations related to the geodynamic evolution of the Sunda. The mantle structure compared by seismic profiles, considering convergent rate of plate motion. Chemical composition distribution of volcanics are correlating with geochemistry studies.