You are browsing the archive for archean.
24 October 2016
Erik Klemetti posted today at Eruptions about komatiite, which is apropos, considering I just finished imaging some samples of that ultramafic volcanic rock. Have a look at three samples from Barberton Greenstone Belt here, each from the 3.27 Ga Weltevreden Formation: Link GigaPan by Callan Bentley Link GigaPan by Callan Bentley Link GigaPan by Callan Bentley And, while we’re at it, here’s one from the Red Lake Greenstone Belt (~3.0 …
2 September 2016
A quick Friday fold – Ulundi Formation, basal Fig Tree Group of the Barberton Greenstone Belt, exposed in a creekbed etched into the trace of the Sheba Fault. This is one of the outcrops I visited one week ago today as part of the pre-IGC field trip to the Barberton. The rocks are iron-rich cherts and pelites that have enjoyed some serious strain, presumably due to movement along the Sheba …
1 September 2016
The news yesterday of 3.7 Ga stromatolites in Greenland prompts a closer look at 3.22 Ga microbially-induced sedimentary structures in the Barberton Greenstone Belt’s Moodies group sandstones.
16 August 2016
First in a series profiling the three unconformities to be found in the North-West Highlands of Scotland. Today: the sub-Stoer unconformity as exposed at Clachtoll. Explore a Proterozoic buried topography topped with coarse, angular breccia.
29 July 2016
A quick Friday fold here from the North-West Highlands of Scotland: These are Lewisian gneisses exposed on a headland northwest of the little outpost of Tarbet (where the Handa Island ferry departs from). I was out there in search of shear zones, but I found plenty of nice folds, too. There are two main folds in the image – a synform in the foreground (yellow), and an antiform in the …
11 July 2016
I’m in the North-West Highlands of Scotland, enjoying spectacular geology and less-than-spectacular weather. I’ve been fairly productive on the GigaPan front, regardless, nipping outdoors when the weather permits to shoot outcrops and landscapes. One set I’m particularly pleased with is this suite of four images. They show the Archean-aged Lewisian gneiss, the oldest rock unit in the North-West Highlands, as exposed on a beachside outcrop east of Durness, Sutherland. The …
2 May 2016
More 3D models: digital facsimiles of real rock samples. Check them out and explore! Clinker from the Powder River Basin, Wyoming: Ripple marks from the Rose Hill Formation, West Virginia: Meta-komatiite from the Red Lake Greenstone Belt, northern Ontario, Canada:
29 March 2016
Here are a few new images I’ve been working on with my home-based Magnify2 imaging system from GIGAmacro. Archean basement complex gneiss from the Gallatin Range of Montana: Link (If this looks familiar, that’s because one of the samples I imaged with the Photoscan 3D modeling technique and published on Sketchfab the week before last.) Banded iron formation from Minnesota with ooids and stromatolites: Link Intrusion breccia: Link Blue Ridge …
24 March 2016
Pahoehoe “ropes” on a basalt, sample site unknown: Archean gneiss from the Gallatin Range of Montana: Tafoni in Malmesbury Group turbidites, South Africa:
25 September 2015
I don’t think I’ve featured this sample here before… It’s a lovely gneiss from near the trailhead for the Spanish Peaks, near Ted Turner’s Ranch in the Gallatin/Madison Range in southern Montana, not too far from Big Sky. Have fun checking it out in this macro GigaPan: link Happy Friday to all.