EAPSI:Improving Understanding of Magma Storage and Transport Prior to the Minoan eruption at Santorini Volcano

Flaherty Taya T, Glenshaw PA

Investigators

Abstract

Understanding the timescales of magma storage and transport beneath volcanoes is vital to hazard evaluation and risk mitigation. Several recent studies have used diffusion chronometry at Santorini volcano (Greece) to identify the timescales associated with final magma chamber assembly prior to the catastrophic ~1628 BC ?Minoan? eruption. An intriguing aspect of these studies is that the timescale estimates appear to vary depending on the mineral that is used. Orthopyroxene (Opx) crystals suggest very short timescales ranging from days up to ~30 yrs, whereas clinopyroxene (Cpx) crystals give much longer timescales of up to several thousands of years. This project will test a hypothesis that the Cpx have a deeper origin (thus a longer history) in the Santorini magmatic system than the Opx. If this is the case, the Cpx timescales are recording a more complete story of the magmatic processes related to the Minoan magma than the Opx, which only retrieve the final assembly of the pre-eruptive magma chamber. This research will be conducted at the Earth Observatory of Singapore (EOS) with the guidance and technical expertise of Dr. Fidel Costa, a leading researcher in the study of magmatic timescales and techniques used in this project. The pyroxenes will be analyzed for a range of trace element abundances via laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) with a 193 nm Photon Machines laser and a Thermo quadrupole mass spectrometer located at the EOS. Using existing data on trace element partitioning between pyroxenes, the Minoan Cpx and Opx will be tested to examine: (1) whether they grew in equilibrium with each other, (2) whether they grew in equilibrium with the glass matrix (suggesting crystallization in a shallow reservoir) and (3) the equilibrium conditions (notably the pressure) of crystallization for each pyroxene. It is expected that Cpx will be in disequilibrium with respect to Opx and the glass, and will have a higher equilibrium pressure than that of Opx. The outcomes of this project will have implications for the model of magmatic storage at Santorini, the study of timescales of large explosive volcanic eruptions in general and for the technique of Fe-Mg diffusion chronometry in pyroxenes as a tool for understanding the timescales of magma chamber development and the behavior of active volcanic systems. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the National Research Foundation of Singapore.