SEQUENCE STRATIGRAPHIC CORRELATION OF MIDDLE DEVONIAN STRATA OF THE MID-CONTINENT: ILLINOIS, MICHIGAN, AND APPALACHIAN BASINS

Recent work focusing on the elucidation of the stratigraphic relationships within the Middle Devonian strata of the Appalachian and Michigan basins has lead to the delination of a series of nested depositional sequences representing multiple scales of sea level oscillations during the Eifelian and Givetian stages. Within the confines of both macro- and microfaunal biostratigraphic frameworks, each of the large- (3rd order) and small-scale (4th order) depositional sequences of this interval could be correlated between the two basins, in some cases to the bed level, indicating an extra-basinal control on deposition interpreted as eustatic sea level oscillation. The next step was to extend the sequence stratigraphic correlations into coeval strata of the Illinois Basin. Multiple sections of the Lingle Formation were visited in Union and Alexander Counties of southwestern Illinois in order to obtain as detailed a record as possible for this interval. As with the Appalachian and Michigan basins, a series of depositional sequences were indentifiable at multiple scales, with each of the large-scale depositional sequences of the Michigan and Appalachian basins positively identified. At a large scale, the Howardton Member and basal Microcyclas Zone correlate to the Oatka Creek sequence of the Appalachian Basin, the Tripp Limestone and Meisenheimer Shale members correlate to the Skaneateles Sequence, and the Walnut Grove Member correlates to the Ludlowville and Moscow sequences. 4th order sequences were readilly identifiable within the Tripp Limestone-Meisenheimer Shale members, displaying a very similar pattern to those of the Skaneateles Sequence in both the Appalachian and Michigan Basins.