Devonian stratigraphy, west-central Ellesmere Island, Arctic Archipelago

A Devonian succession in west-central Ellesmere Island, about 5.2 km (3.2 miles) thick, consists mainly of elastic sediments with lesser amounts of carbonates and small amounts of evaporites. The strata are assigned to the previously established Cape Phillips, Imina, Eids, Vehdom Fiord, Blue Fiord, and Hecla Bay Formations, and to the newly erected Red Canyon River and Strathcona Fiord Formations. The Early Devonian record embraces adjacent parts of the Hazen Trough, a deep-· water basin characterized by starved-basin and flysch sedimentation, and of the Franklinian miogeocline. A southeastward, cratonward advance of the Hazen Trough, which had commenced in Early Silurian time , continued into the earliest Devonian (early Lochkovian); subsequently, shore and shelf prograded in westward and southwestward directions . "Reefs" developed at shelf margin in late Early Devonian (late Pragian and Zlichovian) time. Initial movements of the cratonic Bache Peninsula Arch in mid-Early Devonian (latest Pragian-early Zlichovian) time produced an unconformity in the central and eastern parts of the study area. Erosion was followed by alluvial sedimentation, in turn succeeded by elastic, carbonate and evaporitic deposition in lagoonal settings. Strata of latest Early and earliest Middle Devonian (Dalejan and early Eifelian) age demonstrate the transformation of the miogeoclinal carbonate shelf into a fluvia l molasse basin. Fluvial deposition, first (Eifelian and early Givetian) by southwestward- flowing meandering rivers and then by braided streams, continued until about e arly late Devonian (early Frasnian) time. Clastic deposits of earliest Devonian age were derived mainly from northerly sources (Pearya and possibly northernmost parts of the Caledonian orogen), those of midEarly Devonian age from the cratonic Bache Peninsula Arch, and those of Middle to Late Devonian age from a variety of northerly to southeasterly sources. The source terrains consisted mostly of metamorphic-plutonic rocks of sialic composition, but uplifted parts of the Hazen Trough were the source for chert conglomerate. The metamorphic sources of the lowermost Devonian strata were of greenschist facies and the source of younger strata was of amphibolite or higher grade.