Document Type

Thesis

Date of Degree Completion

Summer 2014

Degree Name

Master of Science (MS)

Department

Geological Sciences

Committee Chair

Anne Egger

Second Committee Member

Chris Mattinson

Third Committee Member

Wendy Bohrson

Abstract

New geologic data provides insight into Pliocene strain rates across the southwest Mina deflection. 40 Ar/39 Ar geochronology of geologic units indicate cooling of Miocene ignimbrite at 11.86 ± 0.01 Ma, Pliocene basalt lavas at 3.7241 ± 0.0051 and 3.5262 ± 0.0172 Ma, and basaltic andesite and andesite lavas at 3.4715 ± 0.0107 Ma and 3.1078 ± 0.0088 Ma. Pliocene cinder cones and Quaternary sediments are also exposed in the Huntoon Spring quadrangle. Volcanic units are cut by a dominant set of NNE-, NE-, and ENE- striking sinistral faults and a lesser set of NNW- and NW- striking normal faults. Net NE-oriented sinistral slip across the quadrangle is ~,2,100 ± 200 m, with a minimum strain rate of ~,0.7 ± 0.1 mm/yr. These data indicate that (1) fault kinematics are best explained by a simple shear couple model; (2) north-directed strain from the ECSZ is greater than anticipated; and (3) fault slip is accommodated by diffuse deformation.

Comments

This thesis has been digitized and made available as part of the University’s ongoing preservation and access initiatives. Copyright is retained by the original author. The University has made a good faith effort to review this work for copyright and privacy concerns prior to digitization. If you are the author or a rights holder and have questions, concerns or wish to request removal, please contact ScholarWorks@cwu.edu.

Download

Share

COinS