29 November 2010
Part 6 of the Tavşanlı Zone field trip had us looking at some blueschists and eclogites. Today we conclude the terrific field trip with a brief look at a couple more stops.
We paused along the way in one area to check out the marble and schist layers outcropping in mappable swaths across the hillside, plainly visible beneath the sparse, dry grass:
(The marble is the light colored layers. The schist is dark.)
Our final stop was a pilgrimage to see some rocks that had their blueschist-facies metamorphism (88-80 Ma) overprinted by a later (62-59 Ma) episode of “Barrovian” metamorphism, the standard progression typical of mountain belts. In fact, Donna Whitney’s work in this area has revealed that some rocks were pretty much right at the kyanite-andalusite-sillimanite triple point. Here, specifically, is the rock that exhibited the Al2SiO5 triple point minerals:
I’ll bet you can guess that what caught my eye here wasn’t the mineralogy but that folded band of mylonite. Turkish 1-lira coin (about the same size as a U.S. quarter) for scale.
More of the sheared-out rock:
A folded quartz vein:
…And that’s it! Sorry it took so long to get this last little chunk of the field trip online! Many thanks to our knowledgeable field trip leaders, Aral Okay and Donna Whitney. Thanks also to Northern Virginia Community College for investing in my professional development by covering the cost of the field trip. I learned a lot and collected some great teaching specimens on this trip.