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Durham University

Department of Earth Sciences


Publication details for Dr Darren R. Gröcke

Plint, A.G., Hooper, E.A., Grifi, M.D., Walaszczyk, I., Landman, N., Gröcke, D.R. & Jarvis, I. (2017). Integrated, high-resolution allostratigraphic, biostratigraphic and carbon-isotope correlation of Coniacian strata (Upper Cretaceous), western Alberta and northern Montana. In Allostratigraphy and biostratigraphy of the Upper Cretaceous (Coniacian-Santonian) Western Canada Foreland Basin. Landman, Neil H., Plint, A. Guy. & Walaszczyk, Ireneus New York: American Museum of Natural History. 414: 9-52.

Author(s) from Durham


Inoceramid bivalves are the dominant invertebrate fauna of the Coniacian and basal Santonian of
the Western Canada Foreland Basin in western Alberta. In the upper lower Coniacian through to basal
Santonian, six successive faunas are recognized, which provide the basis for corresponding, formally
defined inoceramid zones. From bottom upward these are the zones of: Cremnoceramus crassus crassus
/C. deformis deformis, Inoceramus gibbosus, Volviceramus koeneni, Volviceramus involutus, Sphenoceramus
subcardissoides, and Sphenoceramus ex gr. pachti. Particular faunas represent assemblages known
widely from the Euramerican biogeographic region, although they characterize mostly its northern,
boreal area. The inoceramid-based biostratigraphic scheme allows correlation with other parts of the
North American Western Interior and with parts of the Euramerican biogeographic region.
The studied succession provides a good record of the Inoceramus gibbosus Zone, which characterizes
the topmost lower Coniacian. This zone, first recognized from northern Germany, is usually
absent, both in Europe and in North America, due to a stratigraphic gap resulting from a eustatic
lowstand. The base of the middle Coniacian is marked by the abrupt appearance of the taxonomically
variable Volviceramus fauna (V. koeneni (Müller), V. exogyroides (Meek and Hayden)), with associated
Inoceramus undabundus Meek and Hayden and Volviceramus cardinalensis, newly described
herein. Scaphites (Scaphites) ventricosus Meek and Hayden, the ammonite marker of the base of the
middle Coniacian first appears in the late early Coniacian. The base of the upper Coniacian marks
the first appearance of the characteristic northern inoceramid species Sphenoceramus subcardissoides
(Schlüter), the appearance of which coincides with Scaphites (Scaphites) depressus Reeside, the
ammonite marker of this boundary. Close to this boundary Volviceramus stotti also appears, which
is newly described from the Canadian sections. The base of the Santonian corresponds to the abrupt
appearance of Sphenoceramus ex gr. pachti (Arkhangelsky).
The studied sections demonstrate that the appearance of new inoceramid faunas (lowest occurrence
of Cremnoceramus crassus crassus (Petrascheck), of various species of Volviceramus, Sphenoceramus
subcardissoides (Schlüter) and of S. ex gr. pachti) takes place immediately above major
marine flooding surfaces, suggesting a close correspondence between evolutionary and/or migration
events and episodes of relative sea-level rise.