Kicked into action: Constraining the width of afterslip in an exhumed strike-slip shear zone

The Quetico shear zone is an ancient, large, dextral, strike-slip shear zone which has accommodated hundreds of kilometers of displacement. The shear zone has been exhumed from greenschist facies conditions (depths of ~15km) and represents an ancient analogue for active deformation along the San Andreas fault. We plan to use the Quetico shear zone as a natural laboratory to better understand rock deformation in active plate margins (such as the San Andreas fault) and determine the state of stress in active shear zones which we cannot directly access due to their great depths. Detailed geologic mapping and sampling by Hanna Tiitto has already been accomplished on this exhumed shear zone, and this collaboration will enable the student to collect high resolution electron backscattered diffraction (EBSD) data on her natural rock samples. These data will be used to analyze the subgrain sizes from various phases, and to use the measured subgrain size to calculate the stresses the rocks were subjected to when they deformed. These data will provide valuable constraints on stress partitioning within active plate boundary faults, with the hope of being able to exploit these observations to better predict earthquakes in active plate boundary fault/shear zones.

Faculty Supervisor:

Pete Hollings

Student:

Partner:

University of Southern California

Discipline:

Earth science

Sector:

Education

University:

Lakehead University

Program: