stratigraphy and oil shale potential - Geology Ontario

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The large volume of drilling carried out as part of the
Oil Shale Assessment Project, and other O.G.S. projects in
southern Ontario, has included the acquisition of twelve
complete cores and downhole geophysical logs through the
Paleozoic sequence (Fig. 5). This has provided an important
supplement to the O.G.S. program of modern surface geological
mapping of southern Ontario begun in the early 1970's. Thus,
as reported by Telford et al. (1984), the O.G.S. is now
attempting to rationalize the conflicting surface and
subsurface terminology in Ontario as a contribution to
standardizing the Paleozoic stratigraphic nomenclature of the
Great Lakes region. The work is far from complete. However,
the stratigraphic terminology used below and elsewhere in this
report reflects the most current usage by O.G.S. (Table 2).
Upper Cambrian/Lower Ordovician. The timing and
character of the earliest Paleozoic marine transgression into
the southern Ontario region are not well understood. Except
for sporadic outcrops of clastic rocks on the eastern and
western flanks of the Frontenac Arch (Fig. 1), Upper Cambrian
or Lower Ordovician strata are restricted to the subsurface.
In southwestern Ontario, these basal units pinch out on the
flanks of the Algonquin Arch and are overlapped unconformably
by Middle Ordovician carbonate units (see below).
From their zero edge on the southeastern side of the
Algonquin Arch, the Cambro-Ordovician units increase in
thickness to about 155 m beneath the Ontario portion of Lake