Tavşanlı Zone field trip, part 3

Picking up where we left off last time, we were in some partly-serpentenized peridotite, part of the Burham Ophiolite in Turkey’s Tavşanlı Zone, an ancient tectonic suture. Our next stop on the field trip allowed us to visit some diabase dikes: Here’s a close-up of the right contact of the dike with the host peridotite: [...]

Tavşanlı Zone field trip, part 1

Before the Tectonic Crossroads conference two weeks ago, I had the good fortune to participate in a Istanbul-to-Ankara geology field examining the Tavşanlı Zone, a tectonic suture zone where a portion of the Tethys Ocean basin closed. This paleo-convergent boundary is marked by a suite of interesting rocks, including blueschists, ophiolites, and eclogites. I’d like [...]

Photos from Virginia Geological Field Conference

For the second year in a row, more exotic travel plans meant that I wasn’t able to attend the superb Virginia Geological Field Conference. I see that they have now posted some photos on the group’s Facebook page, so go check them out to see what we both missed last weekend. Here’s a taste: Sheared [...]

Friday fold: Archean gneiss from Montana

Leftovers*

Today I’m in the air, on my way back to Turkey for the Tectonic Crossroads conference being held in Ankara next week. Before the meeting, I’m joining a field trip to examine a subduction zone complex. Over three days, we will drive from Istanbul to Ankara by way of ophiolites and blueschists and other geologic [...]

Another metamorphosed graded bed

Over the summer, when my blogging access was limited to my iPhone, I uploaded a photo (taken with the iPhone) of a metamorphosed graded bed on the summit of Mount Washington, New Hampshire. Here’s another one that I saw, further down on the mountain, on the Auto Road (famous for its iconic bumper sticker): Lens [...]

Metamorphosed graded bed

This is the coolest thing I’ve seen this week: a graded bed metamorphosed via Acadian mountain building: The graded bed starts at the Swiss army knife at left, where you see an abrupt transition between coarse grained metamorphic porphyroblasts (“pseudo-andalusites”) and finer grained quartzite. This was once a mud to sand transition when these were [...]

S-C fabric in meta-ignimbrite

Here’s a sample from my 2004 geology M.S. thesis work in the Sierra Crest Shear Zone of eastern California. The rock is a sheared ignimbrite (ashflow tuff) tuff bearing a porphyritic texture and a nicely-developed “S-C” fabric. With annotations, showing the S- and C-surfaces, and my kinematic interpretation: S-C fabrics develop in transpressional shear zones: [...]

“Those aren’t pillows!”

In the 1987 comedy Planes, Trains, and Automobiles, John Candy and Steve Martin have a funny experience. It involves a cozy hotel room (one bed only) and the two travelers are huddled up for warmth. As he wakes up, John Candy thinks he is warming his hand “between two pillows.” At hearing this, Steve Martin’s [...]

Crystal ghosts

The first time I went to the Billy Goat Trail (Potomac, Maryland) with geology as the goal (as opposed to mere recreation), it was 2002. The trip was led by a professor at the University of Maryland. I was a graduate T.A. then, and didn’t know anything about the local geology. I remember at the [...]