Understanding the Diverse Isotopic Record of Volcanism in Kamchatka

点击翻译按钮获取中文摘要

This project is to undertake a detailed investigation of the oxygen and radiogenic isotope record of volcanic rocks in one of the most active subduction-related volcanic arcs, the Kamchatka Peninsula, Russia. The study will focus on the geochemical effects caused by the interplay of glaciation and volcanism occurring between the Pleistocene to recent on the three largest multi-caldera centers. This study will add a complementary 40Ar/39Ar geochronologic dataset to the abundant 14 C tephrochronological record that will allow unprecedented calibration of the volcanic stratigraphy of Kamchatka throughout the Pleistocene. This information will be combined with radiogenic isotope measurements by the international collaborators to fingerprint sources and constrain the origin and longevity of 18O isotopic depletions. Kamchatka is ideally suited for this investigation because it hosts the largest subarctic meteoric-geothermal and geyser system on Earth. These oxygen isotope depletions characterize caldera-derived silicic rocks and may be due to assimilation/melting of the very shallow hydrothermally-altered crust. The project will test the model derived from preliminary evidence that links these oxygen isotope depletions to caldera collapse and deglaciation The study proposed here will test the hypothesis that there is a glacial feedback on volcanism, a phenomenon that has rarely been investigated. The results of this research will have important applications to several urgent social issues including climate change, volcanic hazards, and environmental stability in the subarctic. Dating of ignimbrites of major caldera-forming eruptions (100 km3) in Kamchatka will better constrain the record of global volcanism during the late Pleistocene in the context of human settlement of Kamchatka and migration to N. America through the Bering land bridge, and identify major caldera-forming centers for correlation with the ice core record in Greenland and with marine ash sequences in the N. Pacific and Beringia. This project will provide a basis for professional development of a new faculty member, aid in the enhancement of the infrastructure of the newly established stable isotope laboratory at the University of Oregon. The project will also foster international collaborations and allow the training of an identified graduate student as a research scientist as well as provide an opportunity for an undergraduate student to gain significant research experience.