Volcanology and Magmatic Petrology

The research scientists investigate magmatic rock from different regions of the world, using a variety of techniques, which include field geology, textural analysis, and geochemistry (both on bulk-rock and minerals, including trace elements, and isotopes). The group is also active in the area of geochronology and physical modelling, and tries to merge all these techniques, which traditionally have rarely been combined in the earth sciences. Although this multidisciplinary approach poses many challenges, it also represents a promising way to address such complex questions.

Olivier Bachmann focuses particularly on the dynamics and differentiation of magma reservoirs in the Earth’s crust, comparing volcanic with plutonic rock. The samples gathered from across the globe contain information from many different tectonic environments and eras. His group makes use of as many tools as possible in order to draw a coherent picture of these processes.

Currently the scientists are concentrating on establishing a clearer link between volcanic and plutonic rock, seeking out geochemical and textural similarities from field samples to demonstrate a connection between the two classes of rock. Beyond this, the team has developed physical models of melt material extraction from large magmatic reservoirs in the Earth’s crust en route toward the surface. These models are being tested at field locations around the world.

An additional focus is the investigation of so-called eruptive dynamics, the processes involved in the eruption of volcanoes, in particular the transition from effusive lava flow to the explosive emission of magma. While undoubtedly a stunning sight, lava flow poses a true risk to the immediate vicinity of the volcanic cone, only. Explosive eruptions, by contrast, affect regions up to thousands of kilometres away and exert a significant impact on both global economies and on climate. Hence, better understanding this effusive-explosive transition will allow a better assessment of the hazards posed by active volcanoes and an optimisation of the measures taken by society to deal with this threat.

In conjunction with earth scientists around the world, Olivier Bachmann and his team are also very involved in related areas such as the geophysical imaging of magmatic plumbing systems for active volcanoes and in gaining a more comprehensive knowledge of volcanic degassing processes during and in between eruptions.

Volcanology

The research focus in the area of Volcanology is eruptive dynamics and the deposits resulting from volcanic eruptions. This work includes extensive excursions in the field, where different volcanic deposits are sampled and their spatial and temporal interrelations recorded. A particular passion is the so-called phreatomagmatic eruption, which involves magma and lava entering into contact with massive amounts of water. In the investigation of the various processes associated with shallow magma ascent, fragmentation and deposition, a number of different techniques, using observations gained from natural field samples to complement laboratory experiments are applied.

Marine Geology

Gretchen Bernasconi-Green, internationally known as Gretchen Früh-Green, a further member of the Magmatic Petrology group, focuses on the exploration of the oceanic lithosphere exposed on seafloors and on land. The aim of her research is to gain a broader understanding of hydrothermic systems on the seafloor and the conditions under which they form and evolve. A significant aspect of this work is participation in international marine research programs, for example, the International Ocean Discovery Program, IODP.

Gretchen Bernasconi-Green was part of the team that discovered the Lost City in the mid-Atlantic, a previously unknown hydrothermic ecosystem and the greatest known field of rock formations on the seafloor. The Lost City is a collection of towers and spires of ghostly white limestone up to 6 meters in height, which differs significantly from Black Smokers, the underwater hot springs that form near submarine volcanoes.