Upper Cambrian and Lower Ordovician conodont biostratigraphy and revised lithostratigraphy, Boothia Peninsula, Nunavut

摘要

The strata exposed along Lord Lindsay River on southern Boothia Peninsula were previously named the Netsilik Formation, and then recognized as the Turner Cliffs Formation; the interpretation of the age and correlation was based on limited data. New detailed field investigation at 23 localities along the section resulted in the discovery of over 640 identifiable conodont specimens, with 35 species representing 16 genera, among which a new species, Rossodus? boothiaensis sp. nov., is recognized. Five North American standard conodont zone/subzone-equivalent faunas are documented from the section, namely the Hirsutodontus hirsutus Subzone-equivalent, Cordylodus angulatus, Rossodus manitouensis, Acodus deltatus/Oneotodus costatus and Oepikodus communis Zone-equivalent faunas. These faunas enable a new understanding of the age and stratigraphic position of the Netsilik and Turner Cliffs formations on southern Boothia Peninsula. The Netsilik Formation can be correlated with the lower member (except for the lowest part) and upper member of the Turner Cliffs Formation; the previously unmeasured upper part of the section can be associated with the lower Ship Point Formation. Based on the new conodont data, these three units are dated as early Age 10, late Cambrian to middle Tremadocian, Early Ordovician; late Tremadocian, Early Ordovician; and early Floian, Early Ordovician, respectively. This study fills a gap in upper Cambrian and Lower Ordovician biostratigraphy on Boothia Peninsula, and links the regional biostratigraphy to that of Laurentia.