نویسندگان
1 استاد، گروه زمین شناسی، دانشگاه ارومیه، ارومیه، ایران
2 گروه زمین شناسی، دانشده علوم زمین، دانشگاه شهید چمران اهواز، اهواز، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
The Gonbad Pleistocene mafic volcanic rocks from the Northwest Urmia occur on the old floodplain deposits of the Sanandaj-Sirjan zone. The rocks crop out with prismatic and scoria structures. Petrographic and geochemical studies show that the rocks of this region are mostly comptonitic lamprophyre with characteristics comparable to alkali basalts and trachybasalt, with alkaline nature and occur as a lava flow among the basaltic-trachybasalt flows. The lamprophyres are mainly composed of clinopyroxene and some amphibole. All of the rocksshow porphyritic, glomeroporphyritic, and amygdaloidal textures. The Gonbad mafic volcanic rocks are enriched in the Ba, Th, U, and LREE and depleted in the Ta, Nb, Hf, and Rb that are consistent with continental subduction zone settings. After subduction of the Neo-Tethys beneath the Central Iran, a slab break-off occurred in the remnants of Neotethys oceanic crust, just in the collision zone of Arabian-Eurasian plates. Pressure due to oblique direction convergence of the Arabian and Eurasian plates and activity of right-lateral strike-slip fault, resulted from the slab break-off in the Neotethys remnants, caused thermal uplift, decrease of lithostatic pressure in the mantle and decompression melting in the upper mantle. The mafic mantle released melts ascend through that fault system and contaminated by the continental subduction zone materials before eruption.
کلیدواژهها [English]
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