Abstract

The Monte Antola Flysch consists of alternating calcareous turbidites and subordinate non-carbonate "background" sediment. Graded units as much as 28 m thick (but averaging less than 1 m) were deposited by "single events," and one-half to three-fourths of this material is finer than medium silt. Most of the calcareous sediment is shown to be a reworked and sorted pelagic ooze containing abundant coccoliths, planktonic Foraminifera, sponge spicules, and echinoderm fragments. Chert occurs as cement and replacement; calcite is the major cement and replaces sponge spicules.

Evidence for turbidity current emplacement includes repeated graded bedding, microscopic shape sorting, sole markings, Bouma intervals, reworking of Foraminifera, and burrowing from the upper surfaces of beds. All criteria indicate a very distal environment of deposition, and these units clearly show that much of the fine-grained material associated with flysch deposits may be introduced by turbidity currents and not as hemipelagic material.

Reworking of contemporaneous deep-water carbonate oozes into a distal environment of deposition, with sediment ponding yielding theobserved thicknesses, and coupled with the absence of carbonate material in the background sediment, are indicative of abyssal-plain sedimentation, probably at depths below the CaCO3 compensation level (4500 to 5000 m in modern oceans).

The presence of an oceanic basin in the northern Appennines during the Late Cretaceous has considerable significance for hypotheses on the evolution of the Mediterranean region.

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