ABSTRACT

On eastern Axel Heiberg Island erosional outliers of the Miocene-(?) early Pliocene Beaufort Formation overlie with angular unconformity, or are faulted against, Mesozoic and early Tertiary strata. East of Princess Margaret Arch the Beaufort Formation is divisible into three lithofacies: a conglomerate lithofacies interpreted as alluvial-fan deposits, a sandstone-conglomerate lithofacies interpreted as distal alluvial-fan deposits and a sandstone-mudstone-siltstone lithofacies interpreted as alluvial-plain deposits. The floodplain was vegetated by a coniferous forest which was characterized by Picea banksii, Larix, Metasequoia and Alnus. Paleocurrent analysis, facies relationships and petrology of the conglomerates and sandstones indicate the provenance of the Beaufort Formation was Mesozoic strata to the west.

Deposition of the Beaufort Formation on eastern Axel Heiberg Island clearly postdates folding of mid-Eocene and older strata and thus provides a minimum age for orogenesis in this part of the Arctic. The occurrence of faulted massive conglomerates of the Beaufort Formation provides evidence for Miocene-(?) early Pliocene or earlier uplift of ancestral Princess Margaret Arch and a still-later phase of extension.