Tuesday, May 14, 2013

Slickenside Ridge #3

Coming up Slickenside Ridge past the last little slickenside, we came upon this whopper.

It's hard to tell from this photo, but fractured, brecciated, and slickensided dike rock on the far side of the fault plane is juxtaposed against more dike rock, which is what I'm standing on to take the photo. The fault is dipping more or less to the east, and the slickenlines are almost straight downdip (slightly oblique).
A closter view of the lower part of the slickenside.
An even closer view of the lower part of the slickensided surface.
Using the the direction of some of the steps in the slickensides in these photos, I deduce that the motion is normal, with the east or outcrop side down with respect to the west side. This direction would be expected in a Basin-and-Range setting, but the observed steps don't face uniformly upward, so I can't be sure of my interpretation without further work (offset of beds across the fault would be ideal).

We also noticed a nearby cross-cutting fault of minor displacement running about east-west, offsetting this fault and the faulted dike-dike contact by a few feet. Apparent offset across this cross fault was south side to the east (the fault was poorly exposed and dip direction wasn't obvious).
View of "Dike Hill" across Water Canyon.
We made it up to the notable first juniper tree, and stopped to look across the canyon at the dikes, which were blogged about here, here, and here.
We viewed the hill again a little higher up, from this little shadow created by an outcrop of  quartzite.

We then hiked up to our final outcrop and this view of Winnemucca Mountain (on the left beyond the town of Winnemucca) and the Santa Rosa Range (the bluish mountains on the far right).

Our hike wasn't over, though...


Anonymous said...

Beautiful.. Love Water Canyon. Miss Nevada very much!!

-- Sunil

Silver Fox said...

Thanks, Sunil. It's a great place to hike, do geology, live, vacation...hope you can make it back sometime.