32 Structural Geology and Tectonics

Thursday, 19 May 2016
1:00 PM - 3:00 PM
Crest Room

CHENEY AND PALOUSE FALLS FRACTURE ZONE, EASTERN WASHINGTON WITH ANALOGIES TO FRACTURED BASALT CORES

Paper number: 32-5
Program: Technical Sessions
Time: 2:20 PM – 2:40 PM

Authors

Abstract

D-box calculations of two dimensional fracture patters in Columbia River Basalt from the Cheney and Palouse Falls fracture zones were compared to measurements of basalt cores fractured in uniaxial compression tests. One goal is to determine the most likely stress conditions during formation, as there are competing hypothesis to the origins of the natural fractures. Aerial-photo analysis of the three limbs of the Cheney Fracture Zone and the Palouse Falls area find orientations with wide range of orientations and lengths, but are more commonly found trending at approximately 300 degrees azimuth, or N60W. Angles between intersecting fractures are present Fractures commonly intersect at 30 degrees, or less, in map view. Initial D-box values correlate for the Cheney and Palouse Falls fracture zones as well as fractured basalt cores. Understanding more about the fractures is socially important because they may act as hydraulic conduits for infiltration to aquifers as well as mixing between basalt aquifers. Preferential erosion of the fractured rock occurred during Pleistocene glacial outburst floods, which resulted in unique lake forms and river channels, as well as removing kinematic indicators from many of the fracture zones (i.e. potential fault surfaces or lineations).

Geological Society of America Abstracts with Programs. Vol. 48, No. 6

doi: 10.1130/abs/2016RM-276049

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