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GEOREF RECORD

Stratigraphic architecture of a net-transgressive marginal- to shallow-marine succession; upper Almond Formation, Rock Springs Uplift, Wyoming, U.S.A.

Rachel L. Kieft, Gary J. Hampson, Christopher A. L. Jackson and Eirik Larsen
Stratigraphic architecture of a net-transgressive marginal- to shallow-marine succession; upper Almond Formation, Rock Springs Uplift, Wyoming, U.S.A.
Journal of Sedimentary Research (July 2011) 81 (7): 513-533

Abstract

The upper part of the Almond Formation records the overall retreat of a wave-dominated shoreline and associated lagoons or bays. Exposures of these strata on the eastern flank of the Rock Springs Uplift, Wyoming, U.S.A., enable analysis of their stratigraphic architectures along sections oriented oblique to depositional strike. The upper Almond Formation comprises at least nine vertically stacked regressive-transgressive cycles. The regressive component of each cycle consists of thick (up to 22 m), laterally continuous wave-dominated shoreface and overlying coastal-plain deposits that occur in paleoseaward locations and have abrupt (<400 m) paleolandward pinchouts. The transgressive component of each cycle consists of one or more bay-fill successions that occur in paleolandward locations and gradually thin in a paleoseaward direction. Transgressive bay-fill deposits in each cycle are thick (up to 18 m) and associated with preservation of surfaces that record, in progressively paleoseaward locations: initiation of a lagoon or bay (transgressive surface), erosional retreat of tidal-inlet channels (tidal ravinement surface) and the shoreface (wave ravinement surface), and marine flooding (marine flooding surface). This architecture records regression of a strandplain or wave-dominated delta, and subsequent transgression of a barrier island and spit with associated lagoon or bay. The occurrence of such thick and fully preserved bay-fill successions indicates that accretionary transgressive shoreline trajectories were developed. Strongly-aggradational-to-weakly-retrogradational stacking of successive regressive-transgressive cycles results in a layered stratigraphic architecture, with laterally continuous shoreface sandstone layers interbedded with bay-fill shale layers. Shoreface sandstones layers pinch out up-dip abruptly (<400 m) into bay-fill shales and have limited vertical connectivity. Sandstones within bay-fill and coastal-plain deposits occur as small, laterally discontinuous bodies of variable geometry and connectivity. However, these sandstones may provide additional connectivity where they erode through bay-fill shales between two shoreface sandstone layers.


ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 81
Serial Issue: 7
Title: Stratigraphic architecture of a net-transgressive marginal- to shallow-marine succession; upper Almond Formation, Rock Springs Uplift, Wyoming, U.S.A.
Affiliation: Imperial College London, South Kensington Campus, Department of Earth Science and Engineering, London, United Kingdom
Pages: 513-533
Published: 201107
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 87
Accession Number: 2011-061516
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 4 plates, 1 table, sketch maps
N41°18'54" - N41°18'54", W108°54'06" - W108°54'06"
Secondary Affiliation: Statoil ASA, NOR, Norway
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: 201134
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