Aaron T. Dondale

Thirty-six drill holes from the Morien Syncline, Cape Breton Island have been analyzed to study the thickness and facies variation of the lower Sydney Mines Formation (Westphalian D). Drill holes are of the Cape Breton Development Corporation 'A' series, put down from 1905-1928. This project marks the first time the information contained in these holes has been compiled and used to infer changes in sedimentary strata over the syncline in its entirety. Two sections along the Morien coastline provide additional information on facies and paleoflow.

Coal seams and strata within the Morien Syncline are divided into three stratal packages each tens of metres thick: the Backpit Stratal Package from the top of the Backpit Seam to the top of the Phalen Seam; the Phalen Stratal Package from the top of the Phalen Seam to the top of the Emery Seam; and the Emery Stratal Package from the top of the Emery Seam to the Gardiner Seam. The packages correspond to basinwide cyclothems that probably reflect relative sea-level change in equatorial latitutdes linked to Gondwanan glaciation.

Stratal thickness and facies variation, along with paleoflow data from coastal sections, strongly suggest that the syncline was a paleotopographic low during deposition of the lower Sydney Mines Formation. This is indicated on isopach maps by northward thinning from the syncline axis for most seams and stratal packages. Local thickening southward at some levels suggests that the location of the paleodepocenter may have been centered south of the present syncline axis during some periods. Sandstone and red shale isolith maps show relatively high proportions of these facies south of the syncline axis; this suggests the presence of a more elevated area with well drained conditions on the southern flank of the syncline. Support for the existence of a local depocentre is provided by paleoflow patterns, which run mainly parallel to and transverse to the syncline axis.

A strong northerly paleoflow mode suggests that some infill was supplied from basement (pre-mid-Devonian) sources south of the study area. Deformation during the Permian(?) later accentuated the synform and generated steep dips on the northern limb.

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Pages: 155
Supervisor: Martin Gibling