Title

The Microstratigraphy of the Meadville Member of Lodi, Northeastern Ohio: A Lithofacies Analysis

Degree Year

2000

Document Type

Thesis

Degree Name

Bachelor of Arts

Department

Geology

Abstract

During the Lower (Osagian) Mississippian Period, Ohio was about 7 degrees south of the equator in a tropical epicontinental sea at the northwestern edge of the Appalachian foreland Basin. Present day Lodi, northeastern Ohio, lay within the midst of a westward deepening syncline whose sediment was derived from the Acadian uplifts to the east. This sediment, composed primarily of illite and quartz, was deposited about 100 m below sea level in a middle to outer deltaic environment. From the base (Meadville Member) to the top (Armstrong Member) of the strata exposed at Lodi, a general increase in grain size occurs. This upward coarsening trend represents an overall regression that occurred some 345 million years ago. Shale packages and concretionary horizons are indicative of times of quiescence. Sil tstone beds, which are prevalent in the lower 2 m of the strata, represent storm induced channelized grain flows. Paleocurrent data taken indicates that these grain flows, which are upward fining mini-cycles, trended between about N45 degrees E and N66 degrees E. Although historically it was thought that these siltstone beds were uncorrelatable over any distance greater than a few meters, correlation between three beds 95 m apart was achieved based on four concretionary marker beds. Sediment grain-size analysis, macrofaunal identification, and the local correlation of siltstone and concretionary beds (which has lead to the recognition of channelized siltstones) have enabled a Iithofacies analysis to be conducted of the Meadville Member at Lodi City Park.

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