East of Zion

March 16th, 2019

Hurricane, Utah — Today Team Jurassic Utah traveled to Mt. Carmel Junction, east of Zion National Park, to examine the extensive outcrops of the Carmel Formation in the region. The most famous location is in Mt. Carmel Junction itself (MCJ: N 37.22521°, W 112.68095°). It is this crinoid-rich limestone that is reported to be the youngest encrinite in the geological record.

Anna and I measured a two-meter column in this unit to collect samples for thin-section analysis. Four subunits (A-D) start at the bottom of the ruler here.

This is the base of subunit D. It is full of the star-shaped columnals of the crinoid Isocrinus nicoleti. It is one of only three Jurassic crinoid species in North America.

Fieldwork! Love it. Photo by Nick.

Shelley again measured cross-beds to determine current directions here. This was a complicated task because at least three joint sets intersect in these rocks.

Lunch along the Virgin River. Photo by Nick.

After lunch we went just a bit south of Mt. Carmel Junction to examine a Carmel Formation outcrop that looked superficially like it would be identical to the previous unit. We call the place Carmel Cove (CC: N 37.21548°, W 112.68215°). Turns out the limestone here is very different: no crinoids, no ooids, and relatively abundant bivalves. Amazing variability in sections within sight of each other.

 

Trackback URI | Comments RSS

Leave a Reply