Photos from July 2010 Utah Sevier ranges field trip


In July 2010, Willy Guenthner spent a few weeks doing fieldwork and collecting samples in a series of ranges in Utah (Stansburys, Oquirrhs, Wasatch, Sheeprocks, Canyon Range), to reconstruct timing and magnitude of exhumation and kinematics of thrusting in the Sevier fold-n-thrust belt. He was joined by trusty field assistants Kendra Murray, Jerry Kendall, and (for a coupla days) me. Here are a few photos.


The Stansbury Mtns, from the east side. Nice dissected alluvial terrace, baby.

Almost Miller Time.

How's yer aspen? Sorry.

On the ridge looking northeast, through a window of Cambrian quartzites (Prospect Mtn. Fm.) off to the Grateful Salt Lake in the distance. There is a shitload of Cambrian quartzite in this range. Why is there so much late Neoproterozoic and Cambrian quartzite in the pile west of Salt Lake City? Apparently, beneath this are diamictites of the purported Neoproterozoic Snowball Earth episodes.

Our intrepid leader and regional stratigraphic, kinematic, and thermochronologic expert, Dr.(soon-to-be) William Rexford Guenthner.

On top of the Cambrian stuff, and completely overturned in an overturned anticline on the east side, are a bunch of limestones. Here's a big honkin' horn coral in one of them, in one of "the narrows" going up S. Willow Canyon.

Throughout this pile of Cambrian quartzite is regionally pervasive but locally localized (hmm) hematite mineralization. Some makes beautifal Liesegang bands, some coarse hematite xtals on joints, and some in the matrix of hematite breccia (all three in this picture). I collected a bunch to support my "boutique" He dating habit.

Another intriguing thing about the Stansburys is that there is occasional volcanic rock in float, distributed over a huge area, including at the highest elevations. Yet the nearest mapped, in place volcanics (the usual Oligocene flare-up stuff) is way down the range on the east side. Is all this a remnant of in-place volcanics that used to be on top of the quartzites? In an adjacent range that was faulted away in B&R time? It's also interesting to note that the Fe-oxide staining is common in the volcanics, which means it has to be younger than Oligocene...I guess.