Skip to Main Content
GEOREF RECORD

Passive transgression; remarkable preservation and spatial distribution of uppermost Devonian (Famennian) marginal and nearshore marine facies and fauna of western Laurentia

Paul M. Myrow, Devon Cole, David T. Johnston, David A. Fike and Anne Hakim
Passive transgression; remarkable preservation and spatial distribution of uppermost Devonian (Famennian) marginal and nearshore marine facies and fauna of western Laurentia
Palaios (June 2015) 30 (6): 490-502

Abstract

The stratigraphic record of shallow-water shoreline paleoenvironments is characterized by significant facies heterogeneity and laterally discontinuous stratal geometries. In contrast, we investigate a uniquely extensive and microstratigraphically spatially uniform interval of upper Famennian (Upper Devonian) marginal marine strata in the Rocky Mountains. This transgressive deposit (< 5 m thick) rests on a depositional sequence boundary, and is composed of a thin, discontinuous basal transgressive sandstone bed, two thin fossiliferous shale beds, and several meters of oncolite-bearing carbonate wackestone. The lower shale is a consistently thin ( approximately 0.1 m) bed with a fossil fauna of spinicaudatans (clam shrimp or conchostracans), which are extant, bivalved, chitinous, benthic crustaceans that live in fresh to brackish water, in ephemeral ponds, estuaries, and other shoreline settings. Isotopic data for the oncolitic unit record deposition in an epicontinental seaway with restricted circulation and locally brackish conditions. Sulfur isotope data may also reflect short-term changes in redox conditions, consistent with our interpretation of temporary hypoxia during deposition of the spinicaudatan bed, based on its faunal assemblages. The remarkably large areal extent ( approximately 1600 km north to south, and approximately 1000 km east to west) of this uniformly thin interval with marginal marine fauna is one of the most unusual paleoecological events of the latest Devonian in Laurentia. It is considered an artifact of exceptional depositional processes including passive transgression (i.e., little or no wave or tidal ravinement) along with rapid opportunistic takeover of habitats during transgression. The radiation, possibly associated with temporary hypoxia, was aided by the spinicaudatan reproductive strategy of numerous offspring, high growth rate, and rapid reproduction.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 30
Serial Issue: 6
Title: Passive transgression; remarkable preservation and spatial distribution of uppermost Devonian (Famennian) marginal and nearshore marine facies and fauna of western Laurentia
Affiliation: Colorado College, Department of Geology, Colorado Springs, CO, United States
Pages: 490-502
Published: 201506
Other Date: 20150702
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 89
Accession Number: 2015-098643
Categories: StratigraphyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. cols., sketch map
N45°53'60" - N46°51'00", W111°46'00" - W110°58'00"
N39°10'00" - N39°13'60", W113°42'00" - W113°40'00"
N41°38'60" - N41°38'60", W111°43'00" - W111°43'00"
Secondary Affiliation: Harvard University, USA, United StatesWashington University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 201542
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal