Tremadocian carbonates of the lower St. George Group, Port au Port Peninsula, western Newfoundland: Lithostratigraphic setting of diagenetic, isotopic, and geochemistry studies

Detailed stratigraphic measurements and sampling of rocks of the lower St. George Group on the western shore of Isthmus Bay, Port au Port Peninsula, are the foundation for diagenetic, isotopic, and geochemistry studies of Tremadocian shallow-shelf carbonates in western Newfoundland. This article summarizes the lithostratigraphy that hosts the 3rd-order onlap–offlap sequence that marks the first phase of Ordovician carbonate-shelf buildup on the Tremadocian passive margin of Laurentia (in Newfoundland). The succession, which consists of the Watts Bight Formation and lower and middle parts of the Boat Harbour Formation, is bounded at the top by a regional disconformity, the Boat Harbour Disconformity. The base of the succession rests transitionally on peritidal carbonate rocks of the Berry Head Formation of the Port au Port Group. Dolomitization of significant parts of the sequence is described within the context of the regional lithostratigraphy