An Atlantic Mesozoic paleoshelf-edge reef has been inferred from seismic profiles and Scotian Shelf petroleum exploration. The hypothetical reef forms a discontinuous offshore linear trend from Florida to Nova Scotia.

Data from recent Mid-Atlantic deep-water exploration drilling reveal the local nature of the paleoshelf-edge rim. Lower Cretaceous limestone was encountered at anticipated depths. Visual examination of drill cores and petrographic analysis of core thin sections show bioclastic grainstone, packstone, wackestone, floatstone, and rudstone, as well as a small amount of possible boundstone.

The bioclasts are mostly rounded, coarse sand and have thick or thin rinds. The abundant varieties of bioclasts include sponge, coral, echinoderm, bryozoan, bivalve, and algae fragments, with foraminifera, ostracods, calpionellids, and tubiphytes. Some intervals contain large (several centimeters), lobate stromatoporoids, which may be reefal framework elements.

I conclude that some intervals represent carbonate debris buildups and others represent reefal bioherms. Bioclastic debris intervals may result from in-place destruction of fragile calcareous reefal biota.

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