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Author Topic: How are palaeosols identified in Devonian rocks?  (Read 3791 times)

Offline gemlove

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How are palaeosols identified in Devonian rocks?
« on: 08/10/2009 20:31:11 »
How would you find out if there are paleosols in devonian age rocks?  Is it any different than finding just plain old paleosols in sedimentary rocks or does the fact that water played a huge part make this different? Sedimentology is not my thing!


[MOD EDIT - PLEASE FORMAT YOUR THREAD TITLES AS QUESTIONS, IN LINE WITH FORUM POLICY. THANKS, CHRIS]
« Last Edit: 18/10/2009 22:07:52 by chris »


 

Offline frethack

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Re: How are palaeosols identified in Devonian rocks?
« Reply #1 on: 08/10/2009 23:23:19 »
It would appear that there are.  This is the first hit on a google search.

2009 Portland GSA Annual Meeting (18-21 October 2009)
Paper No. 258-15   
Presentation Time: 9:00 AM-6:00 PM
ESTIMATING MIDDLE DEVONIAN SOIL AGES USING POINT-COUNTING OF PEDOGENIC CLAYS IN PALEOSOLS
WRIGHT, Thomas Colby, MINTZ, Jason S., and DRIESE, Steven G., Department of Geology, Baylor University, One Bear Place #97354, Waco, TX 76798-7354,

Determining the duration of soil formation of paleosols in deep time rock records is largely constrained to qualitative assessment of pedogenic development and likewise qualitative descriptions of relative lengths of pedogenesis. We estimate soil ages (duration of pedogenesis) using point-counts of pedogenic clays and other pedogenic constituents in paleosols identified within the Manorkill Formation (Middle Devonian) of the Catskill succession. The Manorkill Fm., which crops out in the Catskill Mountains of south-central New York state, consists of fluvial aggradational cycles (FAC) that were driven by pulses of sediment delivered to the foreland basin from highlands created by the Acadian orogeny and associated eustatic sea-level fluctuations. Establishing the relative ages of the paleosols in the Manorkill Formation can be useful in defining a sequence-stratigraphic framework for this fluvial-deltaic succession as well as providing valuable paleoclimatic information for a pivotal time in Earth's history. A method based upon relative dating of Holocene soil development (Ufnar, 2007) that uses the percentages of illuviated clay as a function of time will be applied to point-count estimates from thin sections prepared from the Middle Devonian paleosols. The hypothesis to be tested is that duration of pedogenesis for stratigraphic intervals was influenced by cyclic changes in accommodation space creation and that this estimate can help define system-tract equivalents in fluvial successions. Many of the paleosols are analogous to modern USDA Vertisols, which are characterized by high clay content and extensive shrink-swell features; shrink-swell processes inhibit preservation of illuviated clay features due to movement of soil materials that breaks apart illuviated clay accumulations, nevertheless they are present in most sampled paleosols. Preliminary observations indicate a range of illuviated clay contents suggesting minimal to extensive pedogenesis for the paleosols, in some cases in association with precipitation of pedogenic calcite.
 

Offline gemlove

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Re: How are palaeosols identified in Devonian rocks?
« Reply #2 on: 09/10/2009 05:33:57 »
Wow, I had no idea that paleosols could be so helpful... As far as formation, the "pulses" of sediment is what I am guessing as some sort of water run-off or mud slides? Interesting. Thanks!!
 

Offline JimBob

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Re: How are palaeosols identified in Devonian rocks?
« Reply #3 on: 10/10/2009 16:44:59 »
The Arabian peninsula is full of fossilized paleosols. Oil production from both Ordovician and Pennsylvanian (upper Carboniferous) glacial deposits are known. And in Oman there are pre-Cambrian glacial soils preserved as well.
« Last Edit: 10/10/2009 16:52:40 by JimBob »
 

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Re: How are palaeosols identified in Devonian rocks?
« Reply #3 on: 10/10/2009 16:44:59 »

 

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