Oregon SEG Student Chapter Field Trip: Summer 2012
Oregon State University and University of Oregon
Epithermal Hg-Au and so Much More!
Mark Ford and Matt Loewen
The Oregon SEG Student Chapter, comprising of both Oregon State University and the University of Oregon, organized a 4-day fieldtrip to examine epithermal Hg-Au deposits in eastern Oregon and northern Nevada and visit the Marigold Mine, a classic example of finely disseminated gold in the Battle Mountain – Eureka Trend of northern Nevada (Figure 1). We had a diverse group as the six participants contained a mix of both graduate and undergraduate students from both schools and included a visiting scientist from Iran. The trip ran from June 18th – 21st, just after finals week and the weekend graduation ceremonies of both schools.
Prior to the trip, we held a 2-hour pre-trip seminar to discuss both the geology of the region and logistics for the trip. We broadcast the seminar live over the internet so that participants from Eugene (University of Oregon) did not need to make the 40 mile drive to Corvallis. Even though it was held at the end of finals week, we had 11 people come to the seminar and had countless more watching on the internet, although truthfully it is likely that only the field trip participants from Eugene watched the show for any length of time. Presenters included Luc Farmer and Steffi Waffron, who both graciously gave their time to present on the Battle Mountain Trend and Buckskin National Mine respectively, even though neither could attend the trip. Mark Ford presented on the geology of the Glass Buttes in the High Lava Plains of Oregon and on gave a brief geologic history of northern Nevada.
Day one started out a bit bleak and rainy but we were able to get out of Corvallis shortly after 8 AM. The rain intensified as we drove up the western margin of the Cascade Mountains, but as is usually the case, the east side of the range was dry and mostly sunny. After a brief stop at the hydrovolcanic Blue Lake maar we then stopped at the famed Sisters Bakery (Sisters, Oregon) for sustenance. After getting our sugar and caffeine fix, we continued on to Glass Buttes. This area of 6.5 – 5.8 Ma rhyolite domes is world renowned for its obsidian but we were more interested in the epithermal, steam-heated opal-alunite alteration and cinnabar mineralization. Mercury was produced in small quantities here from the 1950’s – 1973 and the silica sinter and breccia are well exposed (Figure 2). This is also the site of a geothermal prospect and we discussed the relationship of geothermal potential to past mineralization and local faulting. The evening brought us to Crystal Crane Hot Springs, where we were able to soak the dust off of us (Figure 3) and fall asleep to the serenade of coyotes.
On day two, we drove the site of the Buckskin National Mine, just south of the OR – NV border (Figure 4). On the way up to the over 8000’ summit, we stopped a number of times to look at the local geology and set the scene for the mineralization, which is believed to be concurrent with the initiation of the Yellowstone Hotspot. The mountain is capped by a thick package of silicic sinter which seems to attract the wind! Later, we found our way to the vein deposits that held the gold and silver, mined primarily in the 1920 – 1930’s but there is recent renewed activity in the area. Tuesday night took us to the Mill Creek Recreation Site (BLM), about 15 miles south of Battle Mountain where we relaxed next to a gurgling steam and had a nice campfire (Figure 5).
Day three took us to the Marigold Mine (jointly owned by GoldCorp and Barrick) where we got a great, all-encompassing tour and discussion from chief geologist James Carver. Most of the members in our group had never been to a large, working mine and it was a real eye-opening experience and certainly the pinnacle of the trip (Figure 6). After leaving the mine, we drove to Hart Mountain, stopping at the top of Guano Rim to look at some Tertiary tuffs and the Steens Basalt.
After soaking in the hot springs at Hart Mountain and fighting off the mosquitoes, day four found us slowly picking our way back to western Oregon. We stopped to look at the crescent dunes that form current-day lake shores in the Warner Basin, indicative of a drier time (Figure 7), and examined the “bathtub ring” embossed on the basin walls indicative of previous wetter climates. We stopped to look at the hummocky terrain caused by massive landslides that came off the Winter Rim, another large Basin and Range fault scarp in southern Oregon. We capped the geologic stops by roaming around the Fort Rock tuff ring volcano and discussing hydrovolcanism (Figure 8), bookending our trip with phreatomagmatic volcanism. The way home was clear of clouds providing some awesome views of the snowcapped Cascade volcanoes.
Trip participants included Mark Ford, Chris Gibson, Matt Loewen, Kevin McCartan, Anis Parsapoor and Tim Stimpson (Figure 9). We would like to extend a thank you to the seminar speakers and faculty advisor John Dilles for his support. We would like to extend a special thank you to James Carver and others from the Marigold Mine for their tour which was certainly the highlight of the trip. A special thanks also goes to SEG for providing financial support.
Check the photos in our photo gallery!
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- The Field trip to Quartzville was a success !
- Here is the list of participants: Tyler Roses, Coney Carlson, Pete Taylor, Daniel Eungard, Ashley Cabibbo, Fede Cernuschi, Mark Ford, Matt Loewen, Nathan Pauley, Gary Hattrick, Kurt Winner, Aaron Olson, Anis Parsapoa, Ben Thorpe, Scott Ceciliani, Rocky Barker, Chris Gibson, John Dilles. Check out our photo-gallery and videos pages !