Open Collections

Conodont paleontology of the Permian Sabine Bay, Assistance and Trold Fiord Formations, Northern Ellesmere Island, Canadian Arctic Archipelago

University of British Columbia

A succession of late Early through Medial Permian conodont faunas is documented for the first time from the calcareous, fine grained, quartzose sandstones of the Assistance and Trold Fiord Formations on northern Elles-mere Island, Northwest Territories. Of the taxa identified and described, one species and three subspecies are proposed as new. The taxa include, in chronological order: Neogondolella idahoensis subsp. indet., Neostrep-tognathodus prayi, Neogondolella idahoensis n.subsp. A, Anchignathodus minutus, Neogondolella serrata(?), N. n.sp. B, N. postserrata(?), N. bitteri n.subsp. C, and N. rosenkrantzi n.subsp. D. Numerous ramiform elements are also associated with Neogondolella idahoensis n.subsp. A. These elements may comprise part of a multielement Neogondolella apparatus or they may represent separate form species. In observation of their questionable status, a somewhat unsatisfactory dual taxonomy is proposed for these elements, and includes the following taxa: N. idahoensis n.subsp. A - Xanio-gnathus tortilis, N. idahoensis n.subsp. A - Ellisonia excavata, N. idahoensis n.subsp. A - Ellisonia tribulosa, and N. idahoensis n.subsp. A - Pri-oniodella decrescens. Statistical work on the abundant platform elements of N. idahoensis n.subsp. A provides evidence for minor 'evolutionary trends of increasing size and increasing number of denticles upsection. Comparison of these con-odonts with N. serrata.and N. postserrata from the Great Basin of SW USA suggests that the phylogenetic development of Permian Neogondolella followed an,, evolutionary path.more appropriate to punctuated equilibria than to phyletic gradualism. The conodont taxa indicate that the Assistance Formation is Upper Leonardian to Uppermost Roadian in age whereas the Trold Fiord Formation includes most of the Wordian.stage. These two formations have been separated into five subdivisions on the basis of both lithology. and the presence or absence of various biota 1 A sixth, subdivision is described for the Sabine Bay Formation which underlies the Assistance and where conodonts are apparently absent. Lithologic and biotic evidence (including trace fossils and mega- and microbiota) point to shallow, offshore marine conditions well within the photic zone and characterized by low energy and slow depositional rates, for most of the conodont bearing strata. A much thicker correlative section to the south represents, in large part, a delta front sequence. The Sabine Bay Formation, on the other hand, is composed of shoreface sandstones, possibly in a barrier island setting. The results of this research indicate that conodonts may be very promising for correlation of Permian strata in the Canadian Arctic Archipelago and for worldwide comparison. More work within the Sverdrup Basin, including both marginal and basinal sections , is necessary to provide a good biozonation of these marine Permian strata. The use of the abundant brachiopods in combination with the conodonts is probably the best way to resolve this zonation. The taxonomic.descriptions and subdivisions proposed herein should provide a foundation for future work.

Text

2010-03-24

For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.

http://hdl.handle.net/2429/22458

Geological Sciences

University of British Columbia

Graduate