Minnehaha Member of Upper Devonian Brallier and Scherr Formations of Central Appalachians: ABSTRACT

Abstract

The Minnehaha member of the Upper Devonian Brallier and Scherr formations has been informally named, and its use as a time band within the marine strata of the Devonian Catskill delta complex of the central Appalachians is suggested. The coarse clastic bundle of the Minnehaha member can be identified in both outcrop and subsurface for approximately 150 mi (235 km) along the Allegheney Front from Bedford County, Pennsylvania, to Greenbrier County, West Virginia. The Minnehaha member is 20.9 to 98.4 ft (6.37 to 30.0 m) thick, consisting of interbedded very thinly to thickly bedded medium-gray siltstones and olive gray shales, with some grayish-red siltstones and shales. The Minnehaha member was deposited by turbidity currents in generally unchanneled suprafan environments during the earliest Cohocton Stage. Three major, time persistent, depositional systems are recognized as having contributed to the Minnehaha member. End_Page 1171------------------------------ They are in order, from northeast to southwest, the Fulton, Mouth of Seneca, and Augusta depositional systems. The relatively brief time interval of Minnehaha deposition by three separate depositional systems strongly suggests a sea-level drop in the Appalachian basin as a causal factor. The overlapping of submarine fan deposits from three depositional systems could enhance the hydrocarbon reservoir potential of the Minnehaha member. The Minnehaha member may be the shoreward correlative of the gas productive Sycamore siltstone of north-central West Virginia. End_of_Article - Last_Page 1172------------