Another Friday fold from the pre-GSA Superior Craton field trip: Happy Friday. I’m setting this to auto-post on the day that my wife and I arrive in Johannesburg to start our honeymoon. I hope everyone’s doing well in my absence.
A pretty cool outcrop I saw on my pre-GSA structural geology field trip to the Superior Craton: Can you see what caught my eye here? It’s a nice series of cross-cutting relationships. A series of sedimentary rocks were sheared out and metamorphosed, transforming into schists with internal boudins, and then they were cross-cut by first … Read more
Sorry to be late with this – I think that’s the first time I’ve forgotten to post a Friday fold. Blame it on the tryptophan.
Callan visits a new outcrop of highly-sheared rocks in the basement complex of Virginia’s Blue Ridge province.
The geology program at the College of William & Mary turned 50 years old this year, and last weekend they held a party to celebrate. Of the 800 or so geology majors the department has produced in 50 years, about 100 came to this event – that’s a pretty great ratio, I think: 1 out … Read more
You may recall that I kind of like boudinage. So it piqued my interest when our field trip leaders (on the pre-GSA Minneapolis trip to examine the structural geology of the sub-province boundaries in the Superior Craton) said our next stop was to visit “pseudoboudins,” segments of granitoid pegmatites that looked like boudins but probably … Read more
After the awesome outcrops and pavements of strained metaconglomerates from the Quetico / Wabigoon subprovince boundaries of the Superior Craton, my pre-GSA field trip visited the most charmingly-named magma chamber I’ve ever seen, the cuddly-sounding Ottertail Pluton. This is an Algoman-type pluton which is discordant to tonalite-composition gneisses in the area. As with the Giants … Read more
The “Friday fold” is an isoclinal dextrally-asymmetric granitoid vein exposed north of Fort Frances, Ontario. Taken on October 7, 2011, the photo features a centimeter-demarcated pencil for scale. It shows thickened hinges, boudinage of the lower right long limb, and incipient boudinage of the upper left long limb.
The first stop on our pre-GSA field trip to the subprovince boundaries of the Superior Craton was a place just north of Virginia, Minnesota, where the Mesabi Iron Ranges are mined (same Proterozoic banded iron formations that were portrayed as the backdrop of the mining activity depicted in the film North Country). The pull-off is … Read more
Northern Colorado’s route 287 connects Fort Collins, Colorado with Laramie, Wyoming. Along its length, it displays roadcuts into Archean-aged basement complex. Two of these outcrops are featured in this post: one metamorphic (mostly), and a second igneous (mostly), with some intriguing polka-dotted plutons.