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Project

Relating Dauphiné twins in quartz with the threedimensional stress state in the Earth's crust.

In a world, in which the deep subsurface is in great demand not only for the extraction of its natural resources (e.g. shale gas), but more and more as a site for critical infrastructures (e.g. nuclear waste repository) and storage (e.g. Carbon Capture & Storage), it is more than ever imperative to better understand the mechanical behavior of the Earth’s crust, eventually to properly assess the hazards associated with the use of the deep subsurface (e.g. induced seismicity). Characterizing stresses in the Earth’s crust, both in the present and the geological past, is crucial in this endeavor. Our toolbox to reconstruct these stresses is, however, rather limited, in particular looking into the geological past and at depth. Mechanical Dauphiné twins in quartz are a particular, stress-related intracrystalline microstructure. Unfortunately it is not detectable by standard optical microscopy. Only recently, since the introduction of new methodologies using electron backscatter diffraction on a scanning electron microscope, Dauphiné twins can be properly visualized in quartz. Using the maximum potential of recently developed research methodologies (EBSD-OIM, X-ray synchrotron Laue microdiffraction), this research project will further explore the relationship between Dauphiné twins in quartz and steady-state, three-dimensional stress states, driving long-term tectonic deformation. The project will primarily focus on mechanical Dauphiné twinning in naturally deformed, lowgrade metamorphic vein quartz. Since quartz is one of the most abundant rock-forming minerals in the Earth’s crust, the introduction of a novel paleostress gauge, using Dauphiné twins in quartz as an ubiquitous stress recorder, will definitively open new perspectives in stress studies.

Date:1 Jan 2014 →  31 Dec 2017
Keywords:Relating Dauphiné, Earth's crust
Disciplines:Applied mathematics in specific fields, Geophysics, Physical geography and environmental geoscience, Other earth sciences, Aquatic sciences, challenges and pollution, Geomatic engineering