Litho-and chemostratigraphy of the lower to middle cambrian Mount Clark, Mount Cap and Saline river formations in Hornaday River Canyon, Carcajou Range, and Norman Range, Northwest Territories

Abstract

The Lower to Middle Cambrian Mount Clark (sandstone-dominated), Mount Cap (sandstone and dolostone), and Saline River (dolostone, gypsite, and siltstone) formations were deposited in an epicratonic basin that spans northwestern mainland Canada from the eastern Mackenzie Mountains to the Arctic coast (>500 km distance). A cross-section through the three Cambrian formations was developed based on stratigraphic sections documented at surface exposures on the northeastern margin of the basin (Hornaday River canyon), in the west-central part of the basin (Norman Range), and in two southwestern locations near the ancient Mackenzie arch (Carcajou Range). Carbon isotopic (δ13Cvpdb) data for the Mount Cap and Saline River formations show correlatable regional trends that are consistent with part of the Cambrian global composite carbon isotope curve (including the global ROECE and DICE negative carbon isotope excursions), but also highlight local excursions that record phenomena characteristic of specific, localised depositional paleoenvironments near the Mackenzie arch. Carbon isotope chemostratigraphy is here demonstrated to be a robust tool that can augment biostratigraphy in future studies that require correlation of lower Paleozoic strata in northwestern Canada.