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FINAL REPORT Pritchard 2014-2015 Faculty Grant for Applied / Basic Track Research

2014-15 FACULTY GRANTS FOR RESEARCH AND CREATIVE WORKS FINAL REPORT

Principal Investigator Name & Title: Chad J. Pritchard, PhD, LG - Assistant Professor Department: Geology Mail: 130 Science Building, Cheney, Washington 99004-2447 Phone: 509.359.7026 Email: [email protected] Project Title:

DECIPHERING THE CHENEY FRACTURE ZONE USING FRACTURE ANALYSIS Amount Requested $ 9,969.66

Figure 1. Trike flight over Williams Lake looking north, the low angle of sun brought out fractures in center of photo. Tom Tabbert driving in front of trike, Dr. Pritchard in back, amazed


1. Purposeandbackgroundinformationontheproject.

The Cheney Fracture Zone (CFZ) is a series of cracks/fractures in surficial basalt rocks in the West Plains, Spokane County, eastern Washington that has been considered an enigma for decades. The location of these fracture zones are presented in Figure 2.

Figure 2. A: Location map of the Cheney Fracture Zone (CFZ) and the Palouse Falls Fracture Zone (PFFZ), which will be focused on in further studies. Pinkish color represents the general area of the Columbia River Basalt Group and the blue represents large areas of uplifted basement rock. Dark lines represent major regional structures including the Olympic-Wallowa lineament (OWL), Hite fault system (HFS), Lewis-Clark fault zone (LFZ), Straight Creek fault (SCF), Trans-Idaho discontinuity (TID). Map modified from Kuehn (1995) and Joseph (1990). B: Google Earth image of the West Plains with the three groups of fractures (or high density fracture zones – HDFZ), all generally oriented from the northwest to the southeast.

Three linear groups of high density (i.e. many closely spaced) fractures in basaltic rock

make up the CFZ. Speculation by Griggs (1973 & 1976) and our preliminary results suggest that these bizarre fractures are caused by faults in the underlying basement rocks, possibly an extension of the Lewis-Clark fault zone (why earthquakes are common in N. Idaho, as in the news on April 23rd and 24th of 2015). If this hypothesis withstands further analyses then the fractures may extend to great depth and act as conduits for surface water to recharge groundwater, or even as pathways for contamination, to potentially affect needed drinking water supplies in the West Plains. In addition, identifying the origin of these faults is important to understand potential earthquake hazards. In 2001 Spokane experienced a swarm of hundreds of earthquakes, which are thought to have been sourced by a buried fault and may potentially lead to more devastating earthquakes (Wicks et al., 2013). Furthermore, our preliminary results may also suggest that the CFZ played a role in directing outburst floods from Glacial Lake Missoula during the last Ice Age, which resulted in unique landforms, such as the s-shape of Badger Lake and many of the lakes in Turnbull National Wildlife Refuge. These Ice Age Floods are unique


events that have drawn many geologists and hobbyists to Cheney and the surrounding area. Therefore, our study is not only important in the discipline of structural geology, but for the West Plains in general.

2. Statusoftheproject(s).

a) Whathasbeenaccomplished?1. Trike flights have been ongoing and will likely continue. On my own accord, I flew

with Tom Tabbert in October of 2014. These flights have given very valuable observations of the fractures and we are still working on some methods to measure fractures from the trike. Regardless, we have taken numerous hours of film of the fractures and will cut portions to add as supplementary material to future publication.

Figure 4. Trike photo looking northeast at Williams and Badger Lake. The north end of Williams has multiple fractures.

Figure 3. Trike photo looking southwest at the tree lined fractures on the west side of Badger Lake.


Figure 6. Trike photo looking east along fractures just north of Bonnie Lake

Figure 5. Trike photo of more subtle fractures and mima mounds near Tyler, WA


2. The high-precision GPS was purchased using funds from this grant. Thank you very

much. We used to locate and map fractures as part of a GEOL 431 laboratory exercise along the Fish Lake Trail in Spring 2015. This was a very rewarding experience for the students and helpful in understanding the fractures.

Figure 7. Working with the Moble Mapper GPS duing a GEOL 431 lab. Photo courtesy of EWU.

Figure 8. Photo of class and Mobile Mapper 120 GPS. Photo courtesy of EWU.


Figure 9. Photo of fracture along Fish Lake Trail with GEOL 431 course in Spring 2015.

3. Student research was funded as part of this project. We made multiple site visits and the students worked to combine previous data and measure the area of fractures. Results of their project were presented at the 2015 National Conference of Undergraduate Research at EWU: Hennings, C; Lund, B; Pritchard, C (2015) Vertical propagation of lateral slip in basement rock

as instigator for the Cheney Fracture Zone, eastern Washington: A fracture analysis, Abstract, NCUR, April 2015, Cheney, WA

I also presented the work at a Northwest Scientific Association meeting with the following reference: Pritchard, C.J., Hennings, C., Lund, B., Ernst, S. (2015) Possible Influences of the Cheney

Fracture Zone and paleodrainages on basalt aquifers of the West Plains, eastern Washington: Abstract – Talk, Northwest Scientific Association 86th Annual Conference, April 2015, Pasco, WA


Figure 10. Photo of students on a geology trip of Bonnie Lake, fracture in the cliff extends through multiple basalt flows.

Thanks to EPIC for logistical support:)

b)Whatneedstobeaccomplishedbeforetheprojectiscompleted?Results from student work need further review and then I will begin writing again. Manuscript preparation has begun and will continue for the next few months.

3. Resultsorexpectedresults.Results from this study agree with our previous findings that the fracture zones are associated with lateral faults in the basement, such as the Lewis and Clark Fault Zone or the Olympic Wallula Lineament, as shown in the following figure.

Figure 11. Rose diagram showing the relative abundance of the fracture orientation along the Badger Lake HDFZ. Orientations are in quadrant (north-south) and azimuth (0 to 360o). Black zones represent R-fractures and blue zones are R'-fractures. Orientations of two large regional structures are presented for comparison (Fig. 1).


4. Ifthereweredeviationsfromtheproposedprojects,listwhatwasdoneandtherationaleorreasonforthechange.We stuck with our plan, the only deviations were associated with student hours. Students selected to work on the project did not spend as much time as we had anticipated due to each of the students taking numerous and challenging classes. Please stay tuned to www.floodexplorer.org to see student stories associated with the Palouse Falls fracture zone. Thank You Very Much, Chad J. Pritchard, LG, PhD June 17, 2015 REFRENCES: Griggs, AB (1973) Geologic map of the Spokane quadrangle, Washington, Idaho, and Montana: United States

Geological Survey, map I-768, scale 1:250,000.

Griggs, AB (1976) The Columbia River Basalt Group in the Spokane quadrangle, Washington, Idaho, and Montana;

with a section on Petrography, by D.A. Swanson: U.S. Geological Survey Bulletin 1413, 1 sheet, 39 p.

Wicks, C; Weaver C; Bodin, P; Sherrod, B (2013) InSAR evidence for an active shallow thrust fault beneath the city

of Spokane Washington, USA: Journal of Geophysical Research, Solid Earth, v. 118, doi:

10.1002/jgrb.50118.

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