Abstract: The Aftermath of Silurian Faulting in Southeast Michigan, and its Effect on Oil and Gas Exploration
John H. Fowler
In Macomb Township of Macomb County, southeast Michigan, is found a sinuous normal fault extending along a N82°W strike, from end to end only 6 mi long, but with more than 260 ft of maximum displacement at the Trenton level. Through about 3 mi of its midsection extent, the main fault is paired with another normal fault with opposite displacement sense, forming a very narrow graben. The timing of development of this divergent wrench feature coincides with Caledonian tectonic activity, a period of intense structural disturbance and regional subsidence throughout the Michigan basin. The fault appears to cut no higher than A1 Carbonate, although relationships are obscured by subsequent dissolution of more than 500 ft of Salina A1, A2, B, D, and F salt along and beyond the trace of the fault. Collapse of interbedded carbonates and shales is evident, although the apparent lack of brecciation indicates salt removal was not rapid. Further, salt removal proceeded throughout the Devonian, producing dramatic compensatory thickening in overlying units. The development of this large feature in prime Niagaran reef territory may have prevented the discovery of reefs by obscuring what is otherwise well-known stratigraphy and seismic signature. The presence of oil production in dolomitized fracture zones in the Trenton/Black River rocks of nearby Ontario may point to similar potential yet remaining along the Macomb faulted trend.
AAPG Search and Discovery Article #90984©1994 AAPG Annual Convention, East Lansing, Michigan, September 18-20, 1994