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GEOREF RECORD

Late Devonian climatic change and resultant glacigenic facies of western Maryland

David K. Brezinski and C. Blaine Cecil
Late Devonian climatic change and resultant glacigenic facies of western Maryland (in Tripping from the fall line; field excursions for the GSA annual meeting, Baltimore 2015, David K. Brezinski (editor), Jeffrey P. Halka (editor) and Richard A. Ortt (editor))
Field Guide (Geological Society of America) (2015) 40: 85-108

Abstract

The latest Devonian (Famennian) is characterized by an extensive Southern Hemisphere glaciation. Deposits resulting from this glaciation are present in several formations in the mid-Atlantic region, including the Hampshire, Catskill, Rockwell, and Spechty Kopf. The Hampshire (= Catskill) Formation exhibits a noticeable stratigraphic change upsection from the middle to the top. The middle part consists of thick intervals of red, channel-phase sandstones with thin overbank siltstone and mudstone. These mudstones contain poorly developed, calcareous paleosols. The top of the Hampshire Formation consists of greenish-gray sandstones containing abundant coaly plant fragments, coalified logs, and pyrite, interbedded with thick paleo-Vertisols. The upsection increase in preserved terrestrial organic matter suggests the onset of environmental conditions that became increasingly wet. The Late Devonian escalation in climate wetness culminated in the development of a stratigraphically and spatially restricted succession of diamictite-mudstone-sandstone interpreted as having formed in glacial and proglacial environments. These glacial environments are recorded in the lower Rockwell Formation of western Maryland and contemporaneously deposited intervals of the Spechty Kopf Formation of northeastern Pennsylvania. Sheared and massive diamictite facies are interpreted as lodgement and meltout deposits, respectively; whereas, bedded diamictites are interpreted as resedimented deposits. The diamictite facies is locally overlain by a mudstone facies with variable characteristics. Both the massive and deformed mudstone lithofacies are interpreted as a clast-poor, subaqueous glaciolacustrine deposit. Laminated mudstones are interpreted as forming in quiet glaciolacustrine environments. The pebbly sandstone facies is interpreted as proglacial braided outwash deposits that both preceded glacial advance and followed glacial retreat.


ISSN: 2333-0937
EISSN: 2333-0945
Serial Title: Field Guide (Geological Society of America)
Serial Volume: 40
Title: Late Devonian climatic change and resultant glacigenic facies of western Maryland
Title: Tripping from the fall line; field excursions for the GSA annual meeting, Baltimore 2015
Author(s): Brezinski, David K.Cecil, C. Blaine
Author(s): Brezinski, David K.editor
Author(s): Halka, Jeffrey P.editor
Author(s): Ortt, Richard A., Jr.editor
Affiliation: Maryland Geological Survey, Baltimore, MD, United States
Affiliation: Maryland Geological Survey, Baltimore, MD, United States
Pages: 85-108
Published: 2015
Text Language: English
Publisher: Geological Society of America, Boulder, CO, United States
References: 148
Accession Number: 2016-007658
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. cols., 1 table, geol. sketch maps
N39°19'60" - N39°40'00", W79°19'60" - W78°00'00"
Secondary Affiliation: U. S. Geological Survey, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 201604
Program Name: USGSOPNon-USGS publications with USGS authors
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