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Marine carbonate mud mounds occur 5km northwest of Bay St. Lawrence, Cape Breton Island, on a 160 210m ridge before the upper margin of the Laurentian Channel. The marine carbonate mounds occur subsurface of the Holocene siliciclastic sediments and are thought to be a recent formation. Samples from these < 1m high mounds are of three textural varieties: (1) knobby popcorn clustered, (2) muddy, (3) and erosional. All varieties are highly porous with numerous small pore holes (< 3mm). Internally, the mounds are a low Mg muddy micrite with no lamination. Concentrically banded acicular and radial sparite occurs in pore spaces. They have comparable characteristics with many cold water and marine carbonate formations, but the absence of an abundant biological component and the uncommon internal structure make these marine carbonate mounds unique. Formation of the marine carbonate mounds may originate from hydrocarbon fluid seepage, seawater geochemistry at the sediment interface, the circulation of various pore waters, or the biological activity of various marine biotas.

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Pages: 69
Supervisor: Peter Wallace