stratigraphy and oil shale potential - Geology Ontario

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resources. Previous hydrocarbon discoveries were reviewed by
Winder and Sanford (1972). An O.G.S. deep drillhole near Port
Stanley (Fig. 5), completed in 1983 as part of the Oil Shale
Assessment Project (OGS 82-3; Johnson et al., 1985),
penetrated 36.8 m of Cambro-Ordovician strata within which was
encountered a good show of oil in the depth interval 1125 to
1135 m. This stimulated considerable interest from the
petroleum exploration community.
Middle Ordovician. Following an Early Ordovician
erosional interval, the Middle Ordovician marine transgression
of southwestern Ontario was very extensive and the entire
region was blanketed by a comparatively thick succession of
shallow water, shelf carbonate deposits. The facies
variations inherent in such a depositional system have
produced a complex stratigraphy with lithological changes
occurring both along strike and down-dip into the Appalachian
and Michigan Basins. However, the Middle Ordovician units are
exposed only along a narrow zone, bordering the Precambrian
shield, extending from eastern Lake Ontario to Georgian Bay
and thence along the northern edges of the islands in northern
Lake Huron. Therefore, only the shallower water, basin margin
carbonate deposits can be examined in outcrop. The deeper
water facies, and those closer to sources of terrigenous
sediments from the eastern side of the Appalachian Basin can
be examined only with subsurface data. Consequently, at least
three stratigraphic nomenclature systems (covering the