OCGC Seminar - Nanoparticles Unlock Big Secrets: Silica in Earthquake Rupture and Gold Transport

 

Dr. Christie Rowe
Department of Earth and Planetary Sciences, McGill University 

 

Electrum-quartz slickenside from the Brucejack Deposit, northern BC

Thursday, February 4th 
11:30 a.m.  

233 Advanced Research Complex (ARC)
University of Ottawa 

 

Abstract 

The energy balance of earthquakes indicates that during seismic slip, rocks in fault zones lose their strength. They must gain back their strength afterwards, because the cycle repeats. This realization has sent geologists and earthquake scientists looking for evidence of the specific mechanisms in modern and ancient faults to try to understand this phenomenon.

I will show the results of recent friction experiments and field studies of exhumed, ancient faults which suggest that silica-rich rocks produce a unique wear material which is nanoparticulate and amorphous, with hydrated particle surfaces. This wear material is weakest at high (seismic) slip rates, due to two deformation mechanisms which depend on the temperature of the wear material and the contact age. At mid- to upper-crustal conditions, it crystallizes over decades to centuries to produce fine-grained quartz, leaving a rather ordinary looking vein in the rock record.