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The University of Southampton
Ocean and Earth Science, National Oceanography Centre SouthamptonOur research

Volcanic Processes

Introduction

Volcanoes are the points at the surface where material is exchanged between the inner Earth and the world we live in. On local scales they are a hazard to inhabitants, but consequences of their eruptions in the form of ash and gases can have an impact on significant portions of our atmosphere and biosphere. Emissions from individual volcanic events and from sustained periods of eruptive activity can release large quantities of CO2 which can add to the human impact on the atmosphere. Material deposited around volcanic terrains preserves a sequence of past and present activity. Examining the lavas and pyroclastic deposits in this record provides crucial information on changes in the frequency and composition of eruptions. This “volcanic logbook” can extend back on timescales of thousands of years to tens of millions of years. Scrutinising this logbook provides an insight into the processes occurring in the magma plumbing system beneath the volcano and ultimately to the original source of the magma in the Earth’s mantle. Fluids, driven by heat, circulate in the crust around volcanic systems, re-distributing elements and compounds. Concentration of material by deposition from these fluids generates mineral deposits that provide important economic resources of metals such as copper, zinc, uranium, lithium and gold. Natural reactions between volcanic rock and fluids also produces carbonate minerals which can act as a “sink” or trap for CO2. Potentially, an application of this process could be as a repository for atmospheric CO2 injected back into volcanic rocks.

Research

In the Southampton geochemistry group we are examining volcanic systems around the world to gain a better understanding of volcanic processes by combining field-based evaluation with state of the art analytical techniques. Investigations span a diverse range of magmatic systems, from active stratovolcanoes, through mid-ocean ridges to supervolcanic regimes. Within these systems we are tracking the chemical changes generated by magma inputs and outputs, hydrothermal fluid circulation and evolution of the material in the magma reservoir. Processes generating these changes are monitored using physical, elemental and isotopic measurement of volcanic materials utilising the analytical facilities within the geochemistry group.

Expertise

Geochemistry at Southampton stems from 35 years of analytical development in elemental and isotopic analysis. Facilities and equipment are kept at the forefront of technical developments by our research and by close collaboration with instrument manufacturers. Isotope ratio measurement by mass spectrometry has developed as a fundamental tool to examine volcanic processes. In particular, we utilise high-resolution isotope measurement of Pb, Nd, Hf and Sr. A bi-product of this analytical expertise is the investigation of radionuclides present in environmental and anthropogenic materials. High precision determinations of uranium and plutonium isotopes are fundamental as tracers in nuclear forensic investigations. Analytical expertise in geochemistry extends to micro-analysis of elements and isotopes using techniques such as laser ablation coupled with ICP and MC-ICP-MS. For example, in volcanic systems these tracers are used to track changes in deep processes by examining variations in crystal composition produced during growth in the magma reservoir.

PhD's and Other Opportunities

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