GEOLOGY OF THE BAIE VERTE PENINSULA REVISITED: STRATIGRAPHY AND STRUCTURE OF THE PACQUET HARBOUR GROUP

The eastern Baie Verte Peninsula in Newfoundland is underlain by Ordovician ophiolites and their island arc -arc rift cover that were obducted onto the Laurentian continental margin during the Ordovician Taconic orogeny. These were subsequently deformed and intruded by Silurian syn-volcanic plutons. Intact and dismembered ophiolites host Cu-rich (+/-Au) base metal mineralization, including the past-producing Rambler and Ming mines, and as such are the subject of an ongoing bedrock mapping project. Preliminary structural investigations suggest that the Pacquet Harbour Group comprises a regional F2 syncline that was refolded by an open, northwesterly trending F3 synform. F2 minor folds and stretching lineations with a north to northeasterly regional trend and moderate plunge can be traced around the F3 axis in the Pacquet Harbour Group. The large F2 syncline is open in the south where it exposes a lower sequence of submarine boninites, basalts and five distinctive horizons of felsic to intermediate pyroclastic and flow deposits. Locally abundant felsic volcanic rocks, coarse tuff breccias, widespread hydrothermal alteration, and a high concentration of gabbro dykes suggest proximity to a paleovolcanic vent. The Rambler and Ming massive sulphide mines are associated with the youngest of the felsic horizons and lie in the core of the F2 fold. Overlying these units is a sequence of basalt, boninite, turbiditic wacke, siltstone and volcanogenic conglomerate, and intermediate to felsic pyroclastic rocks. This younger sequence may be correlative with the Snooks Arm Group, cover to the Betts Cove ophiolite. The F3 fold is a late structure and is responsible for the gentle folding of the Betts Cove ophiolite complex to the southeast. The Silurian synvolcanic Cape Brule porphyry appears to occupy the hinge of this regional F3 synform.