MAGIC-Magma-Ice interaction: late Miocene ice thickness and eruption tempo in northern Victoria Land

Coordinatore: Sergio Rocchi, Dipartimento di Scienze della Terra, Università di Pisa

Ente finanziatore: PNRA - Programma Nazionale di Ricerche in Antartide

Budget: 107 500 €.

Partners: IGG-CNR, Pisa - INGV-Pisa - Dipartimento di Fisica e Geologia, Università di Perugia

Durata: luglio 2020 - luglio 2023

The MAGma-ICe interaction project (MAGIC) is designed for the reconstruction of the ice cover evolution by means of glacial volcanology, igneous petrology and isotope geochronology studies, coupled with investigations of the effects of variable ice load on the eruptibility and composition of magma from shallow crustal chambers. Previous investigations on glaciovolcanic lithofacies in northern Victoria Land by members of this team yielded modern paleoclimate-paleoenvironment reconstructions for late Miocene-Pliocene (10-2 Ma), a period in which the Antarctic ice sheet was subjected to warmer conditions than present. In this area, cliffs exposes superb sections of late Miocene shield volcanoes, constructed by multiple eruptions in 2-3 Ma. The warm late Miocene was also characterised by polythermal ice, and is critical for inferring what can be expected in the near future if global warming will persist. Our paleoenvironmental study will also fill in a major gap in the offshore record and is significantly ultra-proximal (ice-contact) with respect to any associated glacial cover, allowing a local, yet widely applicable perspective. MAGIC will also investigate the modulating effects of glacial ice fluctuations on the eruption frequency and magma composition. Dynamic variations in the ice cap extent/thickness modify the state of stress in the crust, which in turn influences the duration and pressure of magma storage in shallow reservoirs. Thus, during glacial periods (high glacial load), magma storage is relatively prolonged, enhancing chemical differentiation. As a consequence, eruption of volatile- and incompatible element-enriched magmas may be favoured upon glacial retreat. MAGIC is designed to investigate, for the first time in Antarctica, the relationships between glacial loading conditions and composition of erupted magmas, also using numerical simulations. This will establish whether feedback exists between glacial conditions and volcanism in this part of the planet.