Paleoenvironments of the Devonian-Carboniferous Blue Beach Member of the Horton Bluff Formation, Nova Scotia, Canada
LE3 .A278 2014
Pufahl, Peir K.
Bachelor of Science
Earth & Environmental Sciences
The Blue Beach Member of the Horton Bluff formation is one of the few fossil sites in the world that contains tetrapod tracks of Tournaisian age. Body fossils and trackways are preserved in a variety of shallow-water lithofacies that provide insight into Romer’s Gap; a discontinuity between the late Devonian fishes and more evolved early Carboniferous amphibians. Detailed sedimentologic description and sampling of a recently acquired drill core of the Blue Beach Member yielded important information regarding the environments these tetrapods colonized. The presence of flaser bedding as well as authigenic glauconite and framboidal pyrite in wavy-laminated mudstone indicates shallow coastal sediments accumulated in brackish or marine environments. The preponderance of tetrapod trackways in supratidal deposits indicate that large amphibians only existed in swampy backshore areas that were saturated with freshwater. The recognition of marine facies in the Blue Beach Member reconciles the longstanding question of whether tetrapods colonized a lacustrine, brackish or coastal marine setting. These findings further illuminate the paleoenvironments of early tetrapods and support the notion that these amphibians were not solely limited to freshwater lacustrine systems.
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