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You are browsing the archive for granite Archives - Page 4 of 8 - Mountain Beltway.

13 November 2012

Neoacadian Inner Piedmont trip, part II: more Walker Top

Today, I’ve got a batch of additional photos of the Walker Top Granite to share, variably mylonitized (sheared out under ductile conditions)… Nice garnets in some spots: Delta porphyroclast: Lovely sheared-out rocks…

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8 November 2012

Neoacadian Inner Piedmont trip, part I: the Walker Top

Check out these lovely images (mouth-watering, even) of the protomylonitic and mylonitic Walker Top Granite of North Carolina’s Inner Piedmont. There’s also some views of the field trip participants and scenery.

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4 November 2012

Animated GIF of the Walker Top Granite

Here’s one of the cool rocks I saw on my pre-GSA-Charlotte field trip to the Neoacadian Inner Piedmont field trip: the protomylonitic Walker Top Granite (~366 Ma crystallization), which was deformed as the terrane it was intruded into got shoved up and to the west (and perhaps the southwest!). Here’s an animated GIF I made to show off one particularly striking bit of float: The rock is dominated by big …

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28 October 2012

Geology and wine in northern Virginia, part I: the Blue Ridge

Callan attends the Geological Society of Washington’s fall field trip, examining the relationship between grape-growing and the underlying geology of two provinces in northern Virginia: the Blue Ridge and the Valley & Ridge. With GSW compatriots, Callan visits Hume Vineyards in the Blue Ridge basement complex and North Mountain Winery in the Shenandoah Valley. This is part I.

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3 July 2012

Granite dikes that have been folded and boudinaged

It seems like a good morning to return to Ontario, and to the Archean shear zones exposed at the Quetico/Wabigoon subprovince boundary of the Superior Craton. Readers will hopefully recall that I spent several days absorbing structural goodness from these rocks on a field trip before the Minneapolis GSA meeting last fall. The trip was led by Basil Tikoff, Bob Bauer, Dyanna Czeck, and Peter Hudleston. Our final Canadian stop …

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27 April 2012

Friday fold: Nashoba migmatite

The Friday fold is a contribution from the Massachusetts Geological Survey. It shows a migmatite with lovely structure. An upcoming (free) field trip to this location will be part of the 2012 Structural Geology and Tectonics Forum: an event readers may be interested in attending

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26 April 2012

Slickensides on a fault cutting granite

Another shot from my pre-GSA structural geology field trip to the Superior Craton last fall, up in southern Ontario, Canada. The image shows slickenlines coated with brownish fault gouge and oxide staining, cutting through a high-potassium granite (see fresh surface at upper left). The slickenlines are little gouged grooves where asperities (bumps) on the block of rock opposite this one ground into this rock along the fault surface as the …

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1 March 2012

Sea Point Migmatite

Callan visits the Sea Point migmatite, a contact between intrusive granite and older metasedimentary rocks, along the west coast of South Africa near Cape Town. His guide? None other than AGU Blogosphere blogger Evelyn Mervine of Georneys!

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25 February 2012

One from the UTEP Reading Room

Incipient mylonitization of a granite/granitoid, as displayed in a sample on a shelf of one of the meeting rooms adjacent to the Reading Room of the Geological Sciences building at the University of Texas at El Paso. Same side, slightly different lighting conditions: I’d call this a protomylonite. Some of you might prefer the term “augen orthogneiss.” No systematic asymmetry of the feldspar porphyroclasts is catching my eye on either …

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16 February 2012

Wyler Aerial Tramway and the Franklin Mountains of West Texas

Riding a cable-car up the side of the Franklin Mountains, Callan checks out the local stratigraphy and structure (and igneous intrusions). Join him on an insightful cruise up several thousand feet and through a billion years of geologic time.

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