زمیندمافشارسنجی گدازههای تراکیآندزیتی اوچبالغ، پژوهشی دربارة ولکانیسم سنوزوییک آغازین پهنة ماگمایی طارم-هشتجین.

The present study focuses on the mineral chemistry data of Early–Cenozoic volcanic rocks in the south of the Tarom-Hashtjin magmatic zone. The Uchbolaq lavas in the north of Zanjan are a part of Oligocene eruptions within the Turkish-Iranian plateau. The microprobe analysis of the andesite-trachyandesites’ samples from this area indicates that the rocks under study composed of, labradorite (An55-66), augite (Wo44 En44 Fs12), Mg-hastangsite ((Na+K)A≥0.50 and Alvi<Fe3+), and Mg-biotite (Fe2+/(Fe2++Mg)>0.3). Based on geo-thermometric calculations, the crystallization temperatures for amphiboles vary from 985 to 941 ºC, and for biotites from 770 to 758 ºC. According to geobarometric measurements, the pressure in amphiboles ranges between 5.3 and 6.5 kbar, and for biotites from 0.9 to1.9 kbar. The mineral chemistry datasets consisting of amphiboles' and biotites' data indicate that the investigated rocks are derived from a calk-alkaline magma with approximately high ƒO2, in a volcanic arc related to the subduction zone and the orogenic setting suites. [ABSTRACT FROM AUTHOR]