火成岩样品的δ56Fe（或δ57Fe）与SiO2具有正相关关系，但岩浆演化过程中Fe同位素分馏机制并不明确。过碱性流纹岩具有较高的FeOT、Na2O、K2O、卤族元素、高场强元素及Sr同位素比值等，较高的Fe含量与其富含霓石、霓辉石、钠闪石和钠铁闪石等富Fe的碱性矿物相一致，这些矿物是研究高硅火山岩Fe同位素分馏的重要“载体”。本项目以澳大利亚Glass House地区一套渐新世“双峰式”火山岩和东昆仑造山带三叠纪火山岩为研究对象，通过岩石学、全岩-矿物主微量元素和Sr-Nd-Pb-Hf-Fe同位素分析，用已知成因、研究程度高的Glass House钠闪碱流岩的形成、演化过程来检验Fe同位素是否分馏，并建立其分馏机制；分析东昆仑造山带过碱性流纹岩中特征元素、同位素富集和亏损的地球化学行为，深入理解岩石成因，揭示其Fe同位素组成特征并探讨高硅火山岩中Fe同位素分馏机制。

The δ56Fe values of igneous rocks increase with increasing SiO2 contents. However, no single petrogenetic mechanism that can give rise to previously reported high δ56Fe in high-silica igneous rocks. The peralkaline rhyolite has higher FeOT, Na2O, K2O, halogen, high field strength elements, Th contents and 87Sr/86Sr ratios. The higher Fe content is consistent with the enrichment of Na- and Fe-rich alkaline minerals, such as aegirite, riebeckite and arfvedsonite. These alkaline minerals are important “carriers” for studying significant iron isotopic fractionation in high-silica volcanic rocks. We choose a set of Oligocene “bimodal” volcanic rocks in Australia and Triassic intermediate-acid volcanic rocks in the East Kunlun Orogenic Belt as our research subjects. Detailed petrologic and geochemical studies will be performed, including analyses on major elements and trace elements for both bulk rock and minerals, bulk-rock Sr-Nd-Pb-Hf-Fe isotope and Fe isotope of representative minerals. We use the formation and evolutionary process of Glass House peralkaline rhyolites to test whether Fe isotopes are fractionated or not and to establish its fractionation mechanism. We aim to reveal the geochemical behaviors of characteristic elements and isotopes for further understandings on the petrogenesis of peralkaline rhyolites. We will also reveal the Fe isotopic composition of peralkaline igneous rocks and discuss the mechanism of Fe isotopic fractionation in high-silica volcanic rocks.