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GEOREF RECORD

Borings in an oomoldic rockground, Pennsylvanian of southeast Utah

David B. Loope
Borings in an oomoldic rockground, Pennsylvanian of southeast Utah
Palaios (June 1994) 9 (3): 299-306

Abstract

The upper surface of an ooid grainstone within the Upper Pennsylvanian Hermosa Formation of southeastern Utah bears abundant borings and is encrusted by syringoporid coral colonies. Aragonite-dominated ooids were cemented on the sea floor by high magnesium calcite and were later leached by meteoric waters to form abundant oomolds. Two lines of evidence show that the bored, encrusted, marine-cemented surface is not a simple synsedimentary hardground: 1) The margins of the micrite-filled borings are mammillate: micrite fills truncated oomolds along the perimeter of the boring. Oomolds (and a leaching episode) therefore predate borings. 2) Rhizoliths within the ooid grainstone (previously interpreted as penetrating from a higher unconformity) are also bored along the encrusted surface, providing corroborative evidence of an exposure event that predated boring and postdated marine cementation. Rather than a sediment-starved episode within a transgressive sequence, this subtle subaerial exposure surface requires an additional cycle of relative sea level change within the marine portion of a Pennsylvanian cyclothem. Borings, long known to provide evidence on the timing of cementation, can also yield important evidence on the timing of dissolution events.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 9
Serial Issue: 3
Title: Borings in an oomoldic rockground, Pennsylvanian of southeast Utah
Author(s): Loope, David B.
Affiliation: University of Nebraska, Department of Geology, Lincoln, NE, United States
Pages: 299-306
Published: 199406
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 28
Accession Number: 1995-010745
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
N37°00'00" - N42°00'00", W114°04'60" - W109°04'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 199504
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