Wooster Geologists

EPHRAIM, UTAH — Generations of Wooster geologists were united today over a common interest:  deformation bands of Utah!!

George Davis (Regents Professor Emeritus and Provost Emeritus, University of Arizona) researched the deformation bands of the Colorado Plateau region of Utah and wrote several very detailed manuscripts.  As we work on a structural analysis of the Sixmile Canyon Formation, we have been using two of his publications rather extensively this past week:  “Structural Geology of the Colorado Plateau Region of Southern Utah, with Special Emphasis of Deformation Bands”…and…”Conjugate Riedel Deformation Band Shear Zones”.

I actually thought that it was a unique twist of fate that Tricia and I were pouring over two of George’s publications last night…and putting our knowledge into use today in the field.

Above is a view of the Sixmile Canyon Formation, the focus of Tricia’s study.  It contains wonderful deformation bands and joints, and it just happens to be located next to two characteristic antithetic normal faults that cut the Wasatch Plateau.

Tricia and I stumbled upon these deformation bands early in the morning…

…and these later in the afternoon.  With all of the deformation bands in the area, we felt like “measuring machines”.  Indeed, we could have used help in the field today from fellow Brunton-lovers!!

In addition to looking for conjugate deformation bands that George describes from his work in southern Utah, we were also trying to identify characteristic “ladder structures” that he identified in the Sheets Gulch area.  Tricia is sampling the deformation bands for further thin section analyses to determine if they show any sign of cataclasis.  Ultimately, she would like to classify the deformation bands, using one of the kinematic classification schemes proposed in the literature.

Here’s Tricia gathering what she considers to be a “small” sample from a prominent deformation band.  You can tell how excited she is about her I.S.!!

One characteristic of this part of the Sixmile is the interesting iron “concretions” that are everywhere.  The photo above shows how abundant that they can be within the unit.

Aren’t these awesome??!!  These iron “chimneys” rise right out of the rock.  Tricia and I will be further investigating the abundance of morphologies of these concretions tomorrow, as we try to tackle some interesting paleo-fluid fronts within the Sixmile.  The past two days have been rather safe in the field, because we saw few mountain lion prints at our localities.  But, tomorrow is another day, and we are hiking back up to the areas where we saw extensive mountain lion “trace fossils”.

Guest Blogger:  Tricia Hall

SIXMILE CANYON, UTAH — After a couple of days seeing a good number of mountain lion footprints, Shelley and I have decided that it is best to turn the attention of my I.S. toward using our new Trimble GPS to track mountain lion movements. We have heard from the local residents that the lions are low in the mountains, and have even ran across a potential “lion den”. Along the way, just in case this project does not pan out, I have measured a few deformation band orientations so that I don’t fail I.S. Just kidding! Here’s what we’ve really been up to the past couple of days….

Yesterday, we tackled the faulting and joint sets within the Flagstaff Limestone to the west of the Sixmile Canyon Formation exposure. The Flagstaff unconformably overlies the Sixmile, and the faulting and jointing relationships will be key in interpreting the deformation bands within the Sixmile Canyon Formation. We made good use of the Trimble to map the Formation and the fault (to the best of our ability). The resulting map, even without postprocessing, shows normal faulting within the Flagstaff complete with drag folds.

Above is the jointed Flagstaff Limestone looking to the north. We measured several units of this formation to determine the offset of the faults. In addition to the Trimble, we used the brand new Laser range finder! It was either the range finder or eye heighting up the mountain…I was all for the former.

After a long day yesterday, we made it out to Sixmile Canyon this morning with the intention of measuring the major joint sets in the morning followed by deformation band measurements in the afternoon. The joint sets were harder to find than we thought, but hopefully after we go through today’s data after I’m done blogging we’ll find that we’re okay on joint sets. The afternoon was pretty warm, but there was work to be done. It was finally deformation band time! We began measuring orientations, collecting samples, and yes, we broke out the Schmidt Hammer. Schmidty proved most effective and will be put back to work tomorrow. We’re well on our way to our self-imposed 300 Schmidty hits!

Schmidty was phenomenal on the deformation band shown above.

We’ll check in later, back to Sixmile Canyon tomorrow!