I’m a PhD student at ETH Zürich (Switzerland) working in the GNG Team, within the Project “Explore”. My interest was drawn to this project specifically because it aims to solve real-world problems in an academic context.
Under the auspices of my supervisors Thomas Driesner and Olivier Bachmann (also part of the team), I will investigate the connection between magmatic intrusions in the TVZ and supercritical hydrothermal resources in their vicinity. I am using numerical modelling tools to simulate the evolution of fluid flow in time and space. The use of numerical simulations can hopefully complement the insights gained from analytical and geophysical methods, and thus allow to obtain an understanding of the fundamentals of the occurrence of supercritical hydrothermal resources in the Taupo Volcanic Zone and beyond.
I only just started my PhD, so I should probably not come to early conclusions ;-) But in general what I like about working in the academia and especially in geology is the fact that most scientific questions are not simply answerable with a simple ‘yes’ or ‘no’. While this strictness is needed and justified in many situations, geological observations can often be interpreted in different ways. Meanwhile, the wide range of methods available nowadays means that a problem can be studied from many different angles. This can complicate the interpretation, but more so it can also help to understand and solve complex problems. The connection between different approaches fascinates me.
Since I only just embarked on my PhD journey, I guess that would be myMaster’s thesis. I studied the evolution of a formerly active, basalt-hosted, Au enriched hydrothermal system in Iceland.
What was the research finding?
Combining field observations, petrographic interpretations and analytical techniques (LA-ICP-MS on pyrite and calcite, δ18O and clumped isotope thermometry on calcite, fluid inclusion microthermometry), I could reconstruct the evolution of the former hydrothermal system, and could put its activity into the context of the regional volcanological history. It seems that the hydrothermal fluids related to a nearby shallow gabbroic intrusion postulated by previous researchers precipitated gold(native and hosted in pyrite) only in the relatively late stages of the hydrothermal system. Petrographic evidence suggests that boiling induced by regional tectonic faulting and/or hydrothermal eruptions potentially were the cause of Au deposition.
Why is it important?
Other researchers showed that Au accumulates in the fluid reservoirs of active hydrothermal systems (e.g. Reykjanes). Epithermal Au deposits in Iceland are believed to be relatively rare, and yet they exist. Consequently, knowledge about their formation in Iceland is rare, and thus this study aimed to try to(partially) close this gap. Meanwhile, knowledge gained from understanding the conditions for metal deposition in epithermal deposits can possibly be transferred to active hydrothermal systems used for their geothermal resources.
Also, some of the methods used (measurements of rare earth elements in calcite and clumped isotope thermometry with calcite) are not yet part of the traditional set of tools used to study epithermal Au deposits or active hydrothermal systems. To me, using these methods illustrated the edge of our current knowledge and the potential for the future.
Where are you?
This was on the island of Elba (Tuscany, in Italy), near the port of Rio Marina.
What are you doing?
The picture was taken by a fellow student during a field excursion to Elba. To be honest the picture looks more impressive/steep than it actually was. But the colourful skarn minerals (hedenbergite, ilvaite, epidote) complement the beautiful hue of the shallow waters of the Mediterranean very well.
Read more about Thierry's experience here.