مشخصات پژوهش

صفحه نخست /The Almogholagh pluton, ...
عنوان
The Almogholagh pluton, Sanandaj-Sirjan zone, Iran: geochemistry, U-(Th)-Pb titanite geochronology and implications for its tectonic evolution
نوع پژوهش مقاله چاپ‌شده
کلیدواژه‌ها
Almogholagh pluton, arc magmatism, titanite dating, Sanandaj-Sirjan zone, Sr-Nd isotopes
چکیده
Subduction relatedgranitoids,generated duringnorthward motion of Arabia and subduction of the Neo-Tethysoceanunder the southernmargin of Eurasia,are found in the Sanandaj–Sirjan zone, western Iran. The Almogholagh pluton (~200 km2), located in the northern Sanandaj-Sirjan zone, isthought to have formedalongthis convergent plate boundary at some timebetweenthe lateMesozoicand early Cenozoic.The pluton is intrusive into the Triassic-Jurassic Hamedan phyllites. Herewepresent geochemical, Sr–Nd isotopic and U-(Th)-Pb titanite data for monzonitic rocks of this complex. The rocks are metaluminous and belong to the low-K calc-alkaline magma series. Silica-rich samples exhibit an affinity to A-type granites as testified by their high Zr, Nb, Ce, Y and low Ba and Srconcentrations. Field investigation, petrography and U-(Th)-Pb titanite dating demonstrate that the Almogholagh pluton emplaced syntectonically during regional deformation between late Jurassic and early Cretaceous times. Subsequently,parts of the pluton weremetamorphosed under lower greenschist-facies conditions in brittle-ductile shear zones. Monzonites and monzodiorites of the Almogholagh pluton are characterized by low initial 87Sr/86Sr (0.7045, 0.7058) and positive εNd(t) values (2.7, 2.8). These features are in line with derivation by partial melting mafic rocks in the lower crust. The overall tectonic regime was characterized by melt formation, ascent and emplacement alongan active continental margin of the Sanandaj-Sirjan zone during a period of arc extension.
پژوهشگران