Геохимическая характеристика источника пород вулкана Дзотол на Юго-Востоке Монголии: финальная генерация расплавов позднего кайнозоя в зоне транстенсии на границе литосферы–астеносферы

Abstract

The purpose of this study is to establish relationship between a source for final eruptions on the Dzotol volcano and those for the whole preceded Late Cenozoic volcanism in the Dariganga field. Major oxides, trace elements, and Pb isotopic ratios in rocks of the volcanic field are indicative for generation of magmatic melts in a homogeneous mantle region. In final eruptions of the Dzotol volcano, rocks show, on the one hand, intermediate geochemical signatures relative to those of other Dariganga volcanic rocks, and, on the other hand, lower Pb isotope ratios. We infer that Dariganga volcanic rocks were derived due to deep degassing of the about 4.47 Ga protomantle and were dispersed at the asthenospheric–lithospheric boundary affected by transtension. The source for the final Dzotol rocks corresponded in depth to the central part of the magma-generating region and displayed the Pb-isotopic protomantle component, previously designated in rare Quaternary Dariganga rocks.