Abstract

In the Boothia Arch region Paleozoic sedimentation had begun by Middle Cambrian time with a marine transgression, and continued uninterrupted into Lower Devonian time. The Middle Cambrian to Middle Silurian part of this sedimentary record can be seen in two formations on the flanks of the Boothia Arch. The basal Lang River Formation, newly named, contains various lithotypes, and in the lower part of the formation, sandstone and sandy dolostone. On Prince of Wales Island this formation contains sandstone-dolostone and dolostone-fissile dolostone cyclothems. The overlying Allen Bay Formation contains a variety of dolostone types but detrital material is generally absent.

Tidal-flat sedimentation predominated during the deposition of both formations, although various laminated dolostones, stromatolite beds, intra-formational breccias and conglomerates, oolites and a few beds with marine invertebrate fossils are evidence of fluctuations between environments of supratidal to shallow subtidal deposition. The differences within and between the two formations can be related to variations in the supply of terrigenous sediment, to differing local depositional and topographic factors and to changes in basin stability. The rock types and their inferred depositional environments appear to be typical of early Paleozoic sedimentation throughout much of the Arctic Lowlands.