Volcanoes pose significant hazards to both communities and
infrastructure (e.g. the 2010 Eyjafjallajökull eruption). Over the last 5
– 10 years, the way we envisage magma storage regions beneath active
volcanoes has advanced significantly. It is now becoming clear that
magmatic systems are vertically extensive (spanning several kilometres)
and, rather than being dominated by melt, comprise predominantly
crystal-rich domains referred to as mush. The emerging mush paradigm has
significant implications for our understanding of volcanic systems and,
specifically, the process that control the transport of melt from magma
reservoirs towards the surface. Placing constraints on the
characteristics of melt transport below active volcanoes is critical for
understanding how magma is extracted from mush-dominated systems prior
to, and during, eruption.
An extremely detailed record of melt transport within mush-dominated
magma storage regions is preserved in cumulate xenoliths, which are
accumulations of crystals brought to the surface by volcanic eruptions.
Xenoliths capture snapshots of the crystal mush below volcanoes,
providing a unique opportunity to reconstruct the behaviour of
mush-dominated magmatic systems. However, direct analyses of these
xenoliths are rare, representing a critical missing link in our
understanding of magmatic processes within volcanic systems. To address
this critical knowledge gap, I will carry out a detailed study of the
petrological and geochemical record of magmatic processes that are
preserved in cumulate xenoliths. This study will enable me to untangle
the processes that control melt transport in mush-dominated magma
storage regions. Importantly, recent numerical models hypothesise that
porous flow within mush-rich systems may represent the primary mechanism
of melt extraction prior to eruption; my research will test this
hypothesis.
My research will utilise state-of-the-art microanalytical techniques,
hosted in Cardiff University’s CELTIC lab, to create high-resolution
major (e.g. MgO, Na2O) and trace element (e.g. Ce, Y) maps of cumulate
xenoliths from plume-related volcanic systems (Tenerife and the
Galápagos). Patterns of chemical zoning preserved in these maps,
alongside petrological observations of crystal morphologies, will then
be used to identify whether porous flow represents an important process
within mush-rich magma storage regions, as hypothesised.
