Petrology
Seyevahid Shahrokhi
Abstract
The Dalayon granitoid is located in the south of Borujerd and, is part of the Sanandaj-Sirjan zone. The lithological composition includes granodiorite, granite, pegmatite-granite, tonalite, quartz diorite, tourmaline-bearing pegmatite, and quartz-tourmaline veins intruded into volcanic and metamorphic ...
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The Dalayon granitoid is located in the south of Borujerd and, is part of the Sanandaj-Sirjan zone. The lithological composition includes granodiorite, granite, pegmatite-granite, tonalite, quartz diorite, tourmaline-bearing pegmatite, and quartz-tourmaline veins intruded into volcanic and metamorphic rocks. The minerals set of granodiorite mass with color leucocratic to mesocratic index mainly minerals quartz, plagioclase, orthose and microcline and secondary minerals biotite, muscovite, zircon, garnet, apatite, rutile, leucoxene, and sphene. The indicator mineral of ferromagnesian in these rocks is biotite, which has a primary nature rich in magnesium and poor in chlorine in composition. The value of Fe/Fe+Mg ratio shows an average 0.44(apfu), that indicates that the studied micas are placed in the range of biotite and between siderophiles and anite poles. The average crystallization temperature of biotites is 681ºC and the average formation pressure is 2.95kb based on the total aluminum of biotites, which indicates formation at a shallow depth. Based on the proportions of MgO- FeO-Al2O3 in biotites, the magma that produced this mineral is of the calc-alkaline type. The existence of relatively high fugacity of oxygen and oxidant environment indicates magma of mantle-crust origin and host rock of magnetite granitoid series and I-type granitic rock for biotites.
