Neil E. Tibert
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Deceased: December 20, 2015
B.Sc. (Honours), 1994
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M. Sc. Thesis
(PDF - 62.8 Mb)
The shales, siltstones and dololutites of the Blue Beach Member (Horton Bluff Formation) contain a rich assemblage of ostracodes, agglutinated foraminifera, serpulid worms, palaeoniscid fish, crossopterygi4an fish, tetrapod trackways, and fossil macrophytes. The ostracodes from Blue Beach were previously interpreted as nonmarine. A re-evaluation of the taxa, however, indicates that most had brackish/marine affinities. This paleoecological information combined with the first reported occurrence of glaucony grains suggest a marine influence on the depositional system.
The shallowing upward sedimentary cycles contain five faunal assemblages as follows: 1. the profundal lagoon dominated by the euryhaline marine Copelandella novascotica associated with glauconitic shale and primary pyrite; 2. the restricted nearshore dominated by opportunistic paraparchitaceans (Shemonaella scotoburdigalensis, Shemonaella tatei and Chamishaella sp.), Cavellina lovatica?, and post mortem Carbonita scalpellus all associated with hummocky cross-stratified siltstone and shale; 3. the upper estuary dominated by C. scalpellus and Carbonita rankiniana associated with pedoturbated calcareous mudstones; 4. the distal lagoon dominated by paraparchitaceans, Bairdia pruniseminata, Geisina sp., and Youngiella sp. all associated with silty glauconitic shale; and 5. the infringing marsh dominated by the agglutinated foraminifera Trochammina sp. associated with calcareous mudstones and in situ plants.
Low diversity, large populations, and dominance characterise the microfossil assemblages resembling recent stressed ecosystems where physical and chemical conditions are unstable. Deposition of these marginal marine sediments occurred during a Tournaisian transgressive pulse in the earliest stages of the Maritimes Basin.
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Pages: 251
Supervisor: David Scott