Chasing Fossils: the Timing and Extent of an Upright Calamites/Lycopod Forest, Pennsylvanian Hermosa Group, SW Colorado

Adams, Cale and Gianniny, Dr. Gary L. (2015) Chasing Fossils: the Timing and Extent of an Upright Calamites/Lycopod Forest, Pennsylvanian Hermosa Group, SW Colorado. [Abstract]

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Abstract

This study investigates a unique Calamites-bearing layer exposed in the Pennsylvanian Hermosa Group, north of Durango, Colorado. In these strata, three previously undocumented localities containing over 65 Calamites and one 4m x 50cm lycopod fossil were identified. These plant fossils are found encased by braided river deposits, composed of trough crossbedded, felspathic-arenites. At the locality providing the best exposure of the three new locations, a 72 meter thick stratigraphic section was measured. Using a combination of biostratigraphic marker-beds and measured sections, the strata were correlated to Sequence Two of the Hermosa Cliffs (Gianniny and Miskell-Gerhardt, 2009). This correlation helps delineate the lateral extent, and the early Desmoinesian age of the Calamites-bearing layer (Eastep and Gianniny, 2013) along a 4.5 kilometer section of the Hermosa Group. These new data update the depositional model for Sequence Two, of Gianniny and Miskell-Gerhardt (2009). In addition to this, these fossils provide evidence for repeated pulses of fluvial deposition and rapid subsidence on this tectonically active eastern margin of the Paradox Basin.

Item Type: Abstract
Created by Student or Faculty: Student
Uncontrolled Keywords: Calamites, Paleobotany, Hermosa Group, Abstract
Subjects: Undergrad Research Symposium > Geosciences
Undergrad Research Symposium
Depositing User: Cale Adams
Date Deposited: 14 Apr 2015 12:32
Last Modified: 15 Apr 2015 08:53
URI: http://fortworks.fortlewis.edu/id/eprint/680


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