Douglas R. MacDonald

B. Sc. Honours Thesis

Sedimentology of Fluvial Red Beds at Waddens Cove, Cape Breton County, Nova Scotia.

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A red bed unit in the Late Pennsylvanian Morien Group at Waddens Cove, Cape Breton County, Nova Scotia, occurs stratigraphically between the fine upper Morien Group and the coarse lower Morien Group. A succession of sandstone and mudstone facies makes up the measured section at Waddens Cove and are indicative of a meandering-fluvial depositional environment and the characteristic sub-environments of that setting. A sandstone facies assemblage represents in-channel deposits which tend to occur within distinct paleochannels. An alternating facies assemblage of sandstones and mudstones represents overbank deposits which occur on the perimeter of paleochannels.

The internal shape and geometry of some sandstone bodies indicates that normal lateral migration of meander bends was inhibited by resistant bank material, hard layers of early-cemented, rooted siltstone. The sandstone bodies contain up to six storeys which indicate vertical aggradation between the stable banks, and each storey contains epsilon cross-stratification which represents later accretion of point bars within the channel. The lateral wings of the channel complex show that during the final stage the river flowed in a broad, shallow channel cut into less-resistant material. Large-scale slump blocks of bank material occur at the base of the largest paleochannel at Waddens Cove. One possible explanation for the occurrence of the red bed unit within the generally grey Morien Group sediments is that tributaries from different source areas fed into one major fluvial system.

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Pages: 71
Supervisors: Martin Gibling