Paleontology and Paleoecology of the Nada Member of the Borden Formation (Lower Mississippian) in Eastern Kentucky

The Nada Member of the Borden Formation (Mississippian) in northeastern Kentucky was the delta platform deposit of the Borden delta. It consists mainly of iliciclastic mudstones with carbonates and siltstone interbeds. The dominant fossil groups that it contains are crinoids, brachiopods, rugose corals, and bryozoans. Biostratigraphic study bears out that the Nada Member is middle Osagean in age, and again, confirms the westward progradation of the Borden delta. The Nada Member represents the very distal part of the subaqueous delta platform, and it was more controlled by marine processes than by terrestrial influences. The Nada Member has beds with abundant phosphates and glauconites. Field and microscopic study of the phosphates and glauconites indicate that a major transgression occurred at the end of the time of Nada deposition. The abandonment phase of the Borden delta in present-day northeastern Kentucky occurred toward the end of the time of Nada deposition.Community paleoecological study was carried out with the application of the concepts of community components, tiering, and guilds. Biotic interactions were represented in the Nada fauna by the platyceratid-crinoid, the platyceratid-tabulate coral, and the tabulate coral-crinoid relationships. The Nada community was compared with the Edwardsville Formation community of southern Indiana because they were deposited in similar delta platform environment, but at different times. The Edwardsville community ismore diverse and has more guilds than the Nada community. The increase in diversity is a result of the increase in the number of guilds. Temporal changes in the communities (community development or community evolution) have attracted much recent attention in paleoecological studies. A complete comparison of the Nada and Edwardsville mudstone communities was carried out in terms of taxonomy and trophic structures. The community development patterns displayed by the two communities do not support coordinated stasis, but instead, are indicative of coincident relative stability.Crinoids are the predominant group of fossils in the Nada Member of the Borden Formation. Systematics of the Nada Member crinoids are reviewed in this paper. One new genus and four new species occur in this fauna. The new genus is Discocrinus. The four new species are Uperocrinus acuminatus, Aorocrinus nodulus, Discocrinus protuberatus, and Atelestocrinus kentuckyensis. The dominant crinoid group in the Nada is monobathrid crinoids, followed by cladids, and disparids. The fact that monobathrid cameratesdominated the Nada fauna in the mudstone facies counters the general pattern, in which crinoid faunas dominated by monobathrid camerates were largely in carbonate facies.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Geological Sciences

Grantor dc:publisher

The Ohio State University

Year dc:date

2000

Author dc:creator

• Li, Aiguo

Contributors dc:contributor

• Ausich, W.

• Geology
• Mineralogy

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=osu1363693147

OAI identifier oai:identifier

oai:etd.ohiolink.edu:osu1363693147