Stratigraphic sections and reconnaissance studies of the geological structure in widely separated areas of Foxe Basin, Melville Peninsula and Baffin Island
Authors: Trettin H P , Bolton T E , Sanford B V 
Published: March 2017

The lower Paleozoic strata in Foxe Basin and adjacent parts of Melville Peninsula and Baffin Island are preserved in an extensive and complex but shallow depression bounded by normal faults. This depression is flanked by uplifted belts of Precambrian rocks - the
Coastal Uplift of Baffin Island on the northeast, and the Melville Arch on the west. Structural relief on the top of the Precambrian surface is in the order of 2,500 feet (800 m) between northeastern Melville Peninsula and the Rowley Island well. The lower Paleozoic succession totals more than 1,900
feet (580 m), in the centre of Foxe Basin and is divided into four major units: Admiralty Group (pre-late Early Ordovician, possible Cambrian); Ship Point Formation (late Early and early Middle Ordovician); map-unit 0ls (late Middle and Late Ordovician); and map-unit OScb [latest Ordovician(?) and
Early Silurian]. Admiralty Group, Ship Point Formation, and map-unit 0ls are separated by disconformities and represent three, increasingly extensive marine trans gressions. An Early Silurian (early Llandoverian) disconformity recognized in other parts of the craton has not yet been established in
the present area. Both the Admiralty Group and Ship Point Formation are divisible into a basal sandy unit of littoral origin (Gallery Formation and member A, Ship Point Formation) and an upper dolomitic and elastic unit of shallow subtidal to intertidal aspect (Turner Cliffs Formation and member B,
Ship Point Formation). Map-unit 0ls
is a monotonous succession of bioturbated, variably dolomitic, cryptocrystalline linestones with a rich and diverse fauna. It was deposited in subtidal environments of an extensive epicontinental sea. On northeastern Melville Peninsula, a reefal facies (map-unit Orf) developed in latest Middle or
Late Ordovician time. Map-unit OScb, restricted to the centre of Foxe Basin, consists of a variety of dolomitic limestones and dolostones suggestive of shallow subtidal to supratidal depositional environments. There is no evidence indicating that the present Foxe Basin, a shallow, post-glacial sea,
was the site of a separate sedimentary basin in early Paleozoic time. Admiralty Group and Ship Point Formation are thickest in northwestern Baffin Island and wedge out toward the southeast, and the upper Middle and Upper Ordovician succession either retains an essentially uniform thickness over wide
areas or thins out slightly toward the cratonic interior. Lithological variations showing that water depth was greater over Foxe Basin than most other parts of the Arctic Platform also are lacking.
There are, however, indications that the Melville Arch was positive relative to northwestern Baffin Island and Foxe Basin in latest Middle or Late Ordovician time, and perhaps also during the Middle Cambrian-early Early Ordovician interval. The present structural depression in Foxe Basin and
adjacent parts of Baffin Island cannot be dated more precisely than post-Early Silurian but is considered to have formed simultaneously with Baffin Bay and the Coastal Uplift of Baffin Island. The faults bordering the Melville Arch, however , could have had earlier movements , for example during the
Early Devonian. Potential reservoir rocks for hydrocarbons are common in Foxe Basin, and potential traps also are present, but promising source beds are scarce or absent.