Dissertation/Thesis Abstract

Paleoecology of the Lower Devonian Esopus and Carlisle Center Formations (Tristates Group) of New York State
by Senglaub, Michael D., M.S., Bowling Green State University, 2004, 130; 10817772
Abstract (Summary)

The Lower Devonian Esopus and Carlisle Center Formations of New York State are famous for their abundant Zoophycos and lack of other fossils. The goals of this study were to determine the paleoenvironment during the deposition of the Esopus and Carlisle Center Formations, to document any fossils present, and describe any interactions between the trace-makers and other animals.

Numerous fossils are actually present in the Esopus and Carlisle Center Formations, including sponges, conulariids, articulate and inarticulate brachiopods, dacryoconarids, ostracodes, conodonts, and fish bones. Associated with some Zoophycos are Chondrites-like burrows. Chondrites trace-makers may have used Zoophycos traces as a food source.

Assuming a larger, better-fed, trace-making animal will make larger feeding structures, Zoophycos size may be used as a paleoenvironmental indicator. Measurements were made of 312 Zoophycos web radii and 231 meniscus heights from several localities, and compared to data from the Green Pond Outlier collected by Marintsch and Finks in 1978. Zoophycos from the Carlisle Center Formation are consistently larger than those from the Green Pond Outlier, likely because the Green Pond Outlier represents shallower water than the Carlisle Center Formation.

Small (∼10cm wide) unbioturbated lenses are described from the Carlisle Center Formation. These lenses have Zoophycos around them but not within them, and contain a concentration of carbonate fossils. The lenses appear to be gutter casts, filled with material transported by storm currents. Calcium phosphate skeletal elements otherwise predominate within the Carlisle Center Formation. It is likely that there is a preservational bias for calcium phosphate and against calcium carbonate, possibly due to the extensive bioturbation in this interval. Since the bioturbators did not enter the gutter casts, the shelly fossils within them were preserved.

From the presence of glauconite, Zoophycos, and gutter casts (but no tempestite deposits), a water depth of 60 to 100m can be inferred for the Carlisle Center Formation. The Esopus Formation represents somewhat deeper water. The presence of glauconite and Zoophycos also indicate that the Carlisle Center Formation had a low sedimentation rate, and was slightly dysoxic. The Carlisle Center Formation does contain fossils, although many are likely transported or pelagic in origin.

Indexing (document details)
Advisor: Yacobucci, Margaret
School: Bowling Green State University
Department: Geology
School Location: United States -- Ohio
Source: MAI 57/05M(E), Masters Abstracts International
Subjects: Paleoecology
Keywords: Carlisle center formation, Devonian, Esopus formation, Ichnology, Paleoenvironmental reconstruction, Zoophycos
Publication Number: 10817772
ISBN: 978-0-355-84329-3
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