Abstract

The lower Paleozoic facies sequence on New World Island, Newfoundland, can be matched with those of modern deep-sea trenches. New World Island is located immediately to the west of the suture of the early Paleozoic Iapetus Ocean. Its steeply dipping, well-exposed rocks, more than 13 km thick, comprise the following units: (1) the Dunnage Formation (5 km thick), which is interpreted as a mélange produced by tectonic shear along a zone of subduction; graywacke clasts in it may be remnants of an abyssal-plain turbidite succession; (2) the Dark Hole Formation (as much as 500 m thick): graptolitic (Caradoc) laminated mudstones and siltstones, which may correspond to a fine-grained seaward facies of the trench floor; (3) the Milliners Arm Formation (new name) (as much as 5.2 km thick): graywacke turbidites, which may correspond to a coarse-grained axial channel facies with longitudinal sediment dispersal and possibly marginal deep-sea fan development; (4) the Big Muddy Cove Group (new name) (as much as 3.5 km thick), which includes chaotic masses of basalt and Ordovician sediments of the Summerford Group in a mudstone matrix with Llandovery brachiopods; this is interpreted as an olistostrome and may correspond to a (base of) slope facies; and (5) the Goldson Group (as much as 1.4 km thick) with lenses of redeposited clastic material, which may represent small slope basins and some deep shelf deposits with the same Stricklandia subspecies as in the Big Muddy Cove Group. The uppermost part of the Goldston Group contains shallow-water sandstones with Eocoelia curtisi.

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