EAGER: Investigating the Thermal Maturity of Organic Matter in Fault Zones with Laboratory Experiments

Lead PI: Heather Savage, Pratigya Polissar

Unit Affiliation: Seismology, Geology and Tectonophysics, Lamont-Doherty Earth Observatory (LDEO)

March 2012 - April 2014
Project Type: Research

DESCRIPTION: One of the most elusive questions in the study of fault mechanics is how much shear stress faults sustain, which is a necessary parameter for a full description of the rupture process. Because frictional slip generates heat, measuring the temperature increase of fault zones above background temperatures can elucidates the strength of the fault. Here we describe a new paleothermometer that can establish time-temperature histories for faults hosted in sedimentary rocks by examining the thermal maturity of organic molecules within the fault. This technique is widely applied in petroleum geochemistry to determine burial heating.

The investigators will establish a new paleothermometer for fault zones by repurposing an existing paleothermometer used to establish long duration heating associated with burial. Quantifying the frictional heating in a fault zone will allow them to constrain fault and earthquake parameters like shear stress along a fault during failure and slip of the largest event. In order to extend the time-temperature range of this paleothermometer and establish thermal maturity indices at the short time scales and high temperatures that fault rocks experience during earthquakes, the investigators will design and conduct rapid heating experiments on organic-rich sedimentary rocks at various combinations of time and temperature relevant to seismic heating and determine the kinetic parameters of these reactions at short time scales.

Measurement of the coseismic friction is critical for determining the conditions under which an earthquake can expand into a major, societally significant event. This work will devise a new way to directly measure friction from slip on faults.