Geology and some aspects of the paleontology of the Ordovician Long Point formation, Port au Port Peninsula, Newfoundland

Shaikh, Zafar Mohammed (1970) Geology and some aspects of the paleontology of the Ordovician Long Point formation, Port au Port Peninsula, Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

The Ordovician Long Point Formation is present in the northwest part of the Port au Port Peninsula, western Newfoundland, where it also underlies the whole of the dagger-like northeastward extension of the peninsula known as Long Point from which it derives its name. This study is concerned with the geology and some aspects of the paleontology of the Long Point Formation outcrop between Three Rook Point and the village of Black Duck Brook, an area of some thirteen square miles. -- The Long Point Formation consists of fossiliferous limestones, sandstones and shales that have been divided by the writer and Weerasinghe (1970), who studied the geology of the northern part of Long Point, into seven members. Named after their type localities they are, from oldest to youngest, the Tea Cove, Shore Point, Portage, Black Duck, Leroy, Beach Point and Misty Cove Members. The rock types present in each member and the relationship of one member to another are described. -- The beds of the Long Point Formation rest unconformably on the Middle Ordovician rocks of the Humber Arm Group. They strike northeastwards and dip towards the northwest at 40 degrees in the Black Duck Brook area but as they are traced southeastwards towards Lourdes they become vertical and then overturned; since the beds always face to the northwest their structure is homoclinal. Although only minor faults of small displacement affect the formation itself, its boundaries are defined by major faults that separate it from both older and younger strata. -- Fossils collected in the thesis area include brachiopods, bryozoans, cephalopods, crinoid fragments, gastropods, graptolites, ostracodes, tabulate and rugose corals and trilobites. The bryozoan and trilobite faunas are described, the former for the first time, and details are also given of some of the other fossils present. -- The beds of the Long Point Formation were laid down in the shallow coastal waters of a transgressive sea. The abundance of limestones with a varied benthonic fauna and the presence of small columnar reefs built by the tabulate coral Labyrinthites indicate an equatorial marine environment. -- The Long Point Formation is corelated, on the basis of its fossil fauna, with the Ottawa Formation of the Ottawa-St. Lawrence Lowland and its age is regarded as ranging from upper Middle Ordovician to lower Upper Ordovician (upper Wilderness to upper Barneveld Stages).

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