Skip to Main Content

Enigmatic structures in an Upper Pennsylvanian (Kasimovian) marine limestone

R. M. Joeckel
Enigmatic structures in an Upper Pennsylvanian (Kasimovian) marine limestone
Palaios (December 2008) 23 (12): 833-847


Enigmatic structures in the shape of inverted rounded cones are very common in a discrete horizon of the upper Stoner Limestone Member (Stanton Limestone Formation, Lansing Group, Upper Pennsylvanian) in southeastern Nebraska. These structures are 100-300 mm in diameter, but rare, very large examples attain 1300 mm in diameter. On bedding planes, individual structures are conspicuously expressed as groups of concentric rings, some of which appear as low ridges (rugae). At least some of these rings correspond to concentric cone sheets (hollow cones) extending downward into the rock mass; these cone sheets are sometimes separated clearly from each other by discontinuous mud linings or drapes. The largest structures usually have smaller ones nested within them. The Stoner Limestone structures differ from described types of nonbiological and biological conelike structures, yet they must have formed in soft sediment prior to burial. Although they have a superficial similarity to such plug-shaped trace fossils as Conichnus and Conostichus, the purported dwelling traces left by cnidarians, several salient points with respect to shape, structure, and occurrence distinguish the Stoner Limestone structures from such traces. A trace-fossil hypothesis for the origin of the structures remains plausible--possible feeding structures--albeit problematic. Study of the Stoner Limestone concentric-conelike structures indicates that careful reexamination of trace fossils and sedimentary structures in Midconinent Pennsylvanian limestones is in order, as well as a reconsideration of how unique physical and diagenetic properties of carbonate sediments in general might affect the preservation of such features.

ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 23
Serial Issue: 12
Title: Enigmatic structures in an Upper Pennsylvanian (Kasimovian) marine limestone
Author(s): Joeckel, R. M.
Affiliation: University of Nebraska-Lincoln, Conservation and Survey Division, Lincoln, NE, United States
Pages: 833-847
Published: 200812
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 82
Accession Number: 2009-015029
Categories: Sedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: illus. incl. strat. col., sketch map
N40°46'60" - N41°15'00", W96°28'60" - W95°46'60"
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: 200909
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal