Fluid Flow Through Fault Zones in Granite Exhumed from Seismogenic Depths
University of Glasgow, Department of Geographical & Earth Sciences, UK; [email protected]
Fault rock physical properties are crucial for understanding earthquake nucleation and propagation, yet little work has been done on how fluids flowing through a fault zone may alter such properties. There are numerous studies on how faults nucleate, propagate and interact and additionally, the importance of mineral reactions within faults and their ability to cause weakening or hardening of the fault rock is becoming more apparent. However, there is still much work to be done on linking fault structures and growth to fluid movements, mineral reactions, and the associated feedback mechanisms between fault growth, permeability creation or destruction, and fluid flow. This project will examine how fracture systems in crystalline rock control fluid flow through fault zones and how such fluid flow impacts on the mineralogy, geochemistry and hence material properties of the resulting fault rocks. These aims require integrating observations of fault zone structure, metamorphic responses to fluid flow and the timing of fault and fluid flow activity.
In this project I will focus on field observations of two areas. The Monte Rosa nappe (N.Italy) is an excellent example for constraining the nature of fluids flowing through relatively small faults in a fairly juvenile tectonic setting, and the Sierra Nevada (California) has recorded deformation and fluid activity on larger faults and over a much longer timescale. By comparing these two sites we can learn how fluid effects fault rock properties and timescales over which the fluids are present.
AAPG Search and Discovery Article #90083 © 2008 AAPG Foundation Grants in Aid