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Tidal inlet sequence, Sundance Formation (Upper Jurassic), north‐central Wyoming
Author(s) -
UHLIR DAVID M.,
AKERS ARTHUR,
VONDRA CARL F.
Publication year - 1988
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/j.1365-3091.1988.tb01248.x
Subject(s) - geology , shoal , inlet , paleontology , deposition (geology) , barrier island , submarine pipeline , lamination , conformable matrix , sequence (biology) , diagenesis , shore , tidal flat , oceanography , geomorphology , sediment , chemistry , physics , organic chemistry , layer (electronics) , quantum mechanics , biology , genetics
The sandstones and coquinas of the upper 20 m of the Sundance Formation are interpreted as a tidal inlet, back‐barrier shoal and sandy tidal‐flat sequence deposited at the close of marine Jurassic sedimentation in north‐central Wyoming. The barrier strandline maintained a generally E‐W trend as it prograded to the north. The lateral migration of inter‐barrier tidal inlets along the regressive shoreline of the late Sundance sea caused the coquinas and sandstones of the uppermost Sundance Formation to be deposited as tabular, laterally‐extensive units. Tidal bundles, sigmoidal reactivation surfaces, herringbone cross‐lamination and abundant mud drapes within the sandstones are evidence of considerable tidal influence during the deposition of the uppermost Sundance Formation. Earlier models, which attach an offshore environment of deposition to the sequence, do not explain the tabular geometries of the sandstone and coquina units and their conformable stratigraphic relationship with the overlying non‐marine sediments of the Morrison Formation.