Geological setting and paleobotany of the Joffre Bridge Roadcut fossil locality (Late Paleocene), Red Deer Valley, Alberta

The Joffre Bridge Roadcut locality (Paskapoo Formation) in south-central Al berta yields plant, mammal, fish, and insect fossils. A Late Paleocene (Tif fanian) age is indicated by mammalian fossils, supported by magnetostratigr aphy and palynostratigraphy. This paper summarizes the flora (28 taxa have been identified to date) and describes the sedimentology to provide a paleo environmental context. Outcrops at the site are limited, but seven stratigr aphic units are recognized and are interpreted to represent five environmen ts of deposition: flood plain, fluvial channel, abandoned channel, swamp, a nd crevasse splay. The flood-plain mudstones lack identifiable plant materi al due to bioturbation and pedogenesis. They are capped by a thin, clay-ric h paleosol with scattered vertebrate bones. An upward-fining sequence, inte rpreted as fluvial channel and channel abandonment sediments, rests directl y on the paleosol and includes remains of riparian trees. Carbonaceous muds tone, interpreted as a swamp facies, includes remains of only five taxa (ta xodiaceous conifers and riparian trees). Light-coloured mudstones on top of the swamp facies include a more diverse assemblage (aquatic and understory plants, taxodiaceous conifers, and riparian trees). Those beds are interpr eted as the distal margin of an encroaching crevasse splay. Overlying sedim ents coarsen upward and are unfossiliferous, except for one occurrence of a rticulated fish skeletons from a mass-death event. The most productive beds for plant fossils are the top of the channel-abandonment sequence, the swa mp horizon, and the base of the crevasse splay. Those beds have also yielde d some insect, fish, and mammal remains.