ABSTRACT: Structural Analysis of a Portion of Northwestern Ohio

James A. Noel, Marjorie Heidorn, John Krupa, Ronald Shaffer

The geology and geophysical analysis of northwestern Ohio along the Findlay arch was conducted over an extended period by the authors and is as yet incomplete. This paper is a progress report on the work accomplished so far. The work has consisted of extensive reviews of geophysical and drillers logs, detailed gravity and magnetics surveys of Auglaize, and parts of Allen, Hancock, Hardan, Putnam, and Wood Counties. Data from epicenter locations and map patterns on oil field and geologic maps are included.

The structure contour map that has resulted is a compilation of these data and shows several faults in the area. The Bowling Green fault is shown as the eastern boundary of a horst on the top of the arch. The horst is bounded on the west by the Bowling Green split fault. Both extend southward until data are insufficient to map them farther. To the west of the split and trending southwesterly through the center of Auglaize County is the Auglaize fault, which lies in one of the tributaries of the Theys buried valley system. Still farther westward but of much shorter length is the Shawnee fault, which runs from southwestern Allen County into western Auglaize County. This fault also lies in one of the Theys tributaries and a negative gravity anomaly.

The Trenton oils with the exception of a sample from the western Illinois basin are quite similar. The Clinton of Ohio and the Medina of New York are alike but decidedly different from the Niagaran of Michigan. The Devonian shale oils are different from oils from the carbonates of the Illinois basin. The Mississippian oils of the Appalachian basin are different from those of the Illinois basin. Although the Clinton oils are quite different in physical appearance from many reservoirs in Ohio, the NMR curves are all very similar.

The discriminator characteristics of the various oils of different ages from the different basins may be applied to the interpretation of the time of separation of the three basins.

AAPG Search and Discovery Article #90998 AAPG Eastern Section Meeting, London, Ontario, Canada, September 10-12, 1990