Abstract

Baffin Bay is a young ocean basin which opened in the Eocene as a second-stage extension of Labrador Sea spreading. Structures and sediments in the Davis Strait area provide evidence that a series of pre-rift uplifts marked the northward extension of the early Labrador spreading axis, which was transformed successively eastward to a Mesozoic sedimentary trough where Baffin Bay oceanic crust finally appeared.

A mantle plume originally centered east of Cape Dyer supplied material which was extruded in the Disko Island and Cape Dyer areas during the Paleocene. Linear basaltic zones parallel to the later continental margins originated from this same cell, and the Davis Strait sill represents the final position of the plume body. It also determined the location of the successful rift axis.

Late Eocene and younger fluvo-deltaic sediments more than 20,000 feet (6,100 meters) thick unconformably overlie the irregular topography resulting from the tectonically complicated spreading sequence. Section beneath this unconformity includes up to 2,000 feet (610 meters) of Lower Tertiary and Upper Cretaceous, 4,500 feet (1,400 meters) of Middle and Lower Cretaceous, and 1,000 feet (300 meters) of Jurassic and possibly Triassic. Remnants of formerly widespread Paleozoic carbonates may approach 1,000-feet (300-meters) in thickness in places.

A model is proposed to explain the apparent misfit of the Greenland continental margin against the Labrador and Baffin Island shelves, from which movement began in the Late Cretaceous. Early Labrador Sea spreading was accommodated by a series of left-lateral faults trending northeasterly across Greenland. Oceanic crust first appeared in Baffin Bay about 46 million years ago as Greenland moved relatively away from Baffin Island, aided by left-lateral displacement along the Nares Strait Fault Zone. Numerous graben and half-graben features formed in response to tensional fields set up by this second-stage spreading, which ceased about 37 million years ago.