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: [...]

Transect debrief 4: transgression, passive margin

…So where were we? Ahh, yes: an orogeny, and then some rifting. What happened next to Virginia and West Virginia? Let’s consult the column… After the rifting event opened up the Iapetus Ocean, seafloor spreading took place and tacked fresh oceanic crust onto the margin of the ancestral North American continent. As North America (“Laurentia”) [...]

Transect debrief 1: starting in the basement

It is time to debrief the post-NE/SE-GSA field trip that I went on, affectionately dubbed the “Transect Trip” for the past 27 iPhone-uploaded “live”-geoblogged posts. First off, I’d have to say that I enjoyed the live-field-blogging experiment overall, though I’ve got some critiques of the process and products. I think it’s amazing that I can [...]

Transect Trip 27: fluvial overbank deposits

Over on the far right by Chuck Bailey (yellow shirt) you can see the crescent-shaped profile of a river channel (gray color). To the left of that, you can see levee deposits, and beyond that (to the left) crevasse splay deposits and the floodplain (dark red mudstones). This is in the Hampshire Formation, part of [...]

Transect Trip 26: Bouma sequence

Here we are in the Brallier Formation, a Devonian turbidite sequence. Prominent in the middle of this photo is the Bouma “C” horizon with the cross- bedding.

Transect Trip 25: sheared microbrachiopods

This one is also from the Millboro Formation: itty bitty brachs (not too much oxygen in those depths for building up big body sizes) that have been sheared during Alleghanian deformation.

Transect Trip 24: soft sediment deformation

This photo is from the Millboro Formation: mostly deep water black shale, but with the occasional heavy turbidite coursing in and settling its bulk down on the squishy mud beneath. Some folks on our trip suggested these might be seismites: soft sediment deformation resulting from earthquake-induced vibration.

Transect Trip 23: hackle fringe

Nice set of twist hackles on the fringe of this joint face:

Transect Trip 22: S-fold breached by thrust fault

Oriskany sandstone, folded into an S-fold, then snapped down the middle!

Transect Trip 21: hanging wall anticline

Hoo-hoo! An anticline in the hanging wall of a thrust fault in the Valley & Ridge. This is the redbeds of the latest-Ordovician Juniata Formation. Lynn Fichter for scale.