نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه زمین شناسی، دانشکده علوم پایه، دانشگاه لرستان، خرم آباد، ایران
2 گروه علوم زمین شناسی و زمین شناسی مهندسی، دانشگاه کوئینز، کینگستون، کانادا
3 گروه پترولوژی و کانی شناسی، دانشکده علوم، دانشگاه ریودژانیرو،ریودژانیرو، برزیل
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
The Pargeh pluton is located in the northeast of Qazvin. The rocks of this pluton mainly include monzogabbro and olivine gabbro, which mineralogically contain olivine, clinopyroxene, plagioclase, biotite and alkali feldspar. Geochemically, they have features of potassic alkaline magmas with enrichment in large ion lithophile elements (LILE: Ba, U, Pb, Sr) and depletion in high field strength elements (HFSE: Nb, Ti, Zr), which are similar to subduction zone magmatism and mantle-derived magmas. Chondrite-normalized REE plots show enrichment in light REE (LREE) (4.43< (La/Yb) N <8.58)) and slight negative anomalies (Eu/Eu* = 0.82-0.99). The studied gabbroic rocks have resulted from fractional crystallization of a parental magma which formed by partial melting of depleted lithospheric mantle with spinel-peridotite composition. The primary ratios of 87Sr/86Sr and 143Nd/144Nd (0.70493-0.70525 and 0.51272-0.51269) are compatible with the parental magma formation in the mantle wedge. The values of ɛNd(i) (1.47 to 1.92) are in the range of mantle-derived melts. We suggest that Pargeh gabbroic rocks are part of the Alborz magmatic belt, which according to the geochemical data, their tectonic setting is consistent with a post-collisional, back-arc extensional environment.
کلیدواژهها [English]