زمین شناسی و سنگ شناسی آتشفشانی و توده نفوذی پلاژیوگرانیتی در ناحیه زاغ دره، کمپلکس افیولیتی اسفندقه- فاریاب، جنوب خاور ایران

The Zaghdareh area in the Esfandagheh-Faryab ophiolitic complex, southern Sanandaj-Sirjan belt, embraces extensive outcrops of mafic-intermediate lava flows and a felsic intrusive body. The volcanic rocks are calc-alkaline to tholeiitic, metaluminous, and distinguished by depletions in light rare earth elements and relatively flat patterns for heavy rare earth elements in chondrite-normalized diagram; the (La/Yb)N ratio is lower than unity for most samples. The chemical attributes for the Zaghdareh volcanic rocks are comparable to those developed in suprasubduction zones. The Zaghdareh intrusive body is distinguished by abundant plagioclase and quartz, and subordinate hornblende, phenocrysts in quartz-feldspar rich matrix. Representative samples from the intrusion plot in the trondhjemite-tonalite fields in the normative An-Ab-Or diagram. The intrusion is calc-alkaline to tholeiitic, peraluminous, and marked by enrichments in Na۲O and CaO and depletions in K۲O, Rb, and most other LILEs, as well as low K۲O/ Na۲O ratios, very low Rb/Sr ratio, and distinct depletions in light rare earth elements, which are typical of the oceanic plagiogranites. Results from this study and a comparison with other ophiolitic suites in Iran suggest that the occurrence of plagiogranites is a recurring feature associated with the development and evolution of ophiolitic suites in suprasubduction zones.

کلیدواژه ها:

زاغ دره ، افیولیت اسفندقه-فاریاب ، پلاژیوگرانیت ، تونالیت-ترونجمیت ، زون سنندج-سیرجان