mmew 2014 field trips
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MMEW 2014 Field trips. Trip 1, June 18 Trip 2, June 19 Minnesota River Valley. Precambrian Terranes of Minnesota. The Minnesota River Valley Gneiss Terrane 3.6-3.1 Ga. THE MINNESOTA RIVER VALLEY. Actually it’s 3,485,000,000 years ±10,000,000 but hey, close enough. - PowerPoint PPT PresentationTRANSCRIPT
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MMEW 2014 Field tripsTrip 1, June 18Trip 2, June 19
Minnesota River Valley
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Precambrian Terranes
of Minnesota
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The Minnesota River Valley Gneiss Terrane3.6-3.1 Ga
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THE MINNESOTARIVER VALLEY
Actually it’s3,485,000,000 years
±10,000,000but hey, close enough
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GRANITIC (= continental)
GNEISS (= high grade metamorphic)
Amphibolite (oceanic crust?)
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Geologic Structure of Southwestern Minnesota
SMOG mapsuperimposed gravity
(color) on aeromagnetics
(grayscale)
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Yellow Medicine Shear Zone
Composed of garnet maficgneiss and amphibolite (ocean crust in suture zone?)
A suture zone between the Morton and Montevideo Blocks?
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You are here.
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From Pat Colgan
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till
glacial stream sediment
glacial lake sediment
modern stream sediment
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Lisiecki and Raymo, 2005
Blue spikes represent glacial periods
780,000 years ago
2.58 million years ago
1.66 million years ago
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Series of old tills on
Yellow Medicine River cut
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…and it’s potential impact on global climate
Talk by former student and TA, Andy Breckenridge
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Scour surfaces flanking main channel
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Low relief till plains and ice lobe troughs
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