23 D15. Paleontology (Posters)

Friday, 20 March 2020
1:30 PM - 5:30 PM
Grand Ballroom A–D

PRELIMINARY RESOLUTION OF THE ANOMALOUS OCCURRENCE OF THE BRACHIOPODS MARTINIA GALATAEA AND M. THETIS IN THE MISSISSIPPIAN BIG COVE FORMATION, PORT AU PORT PENINSULA, NEWFOUNDLAND, CANADA

Paper number: 23-8
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

In 1929, W.A. Bell established five informal faunal zones for the Windsor Group (Mississippian, Visean) of Nova Scotia, and later applied to the laterally equivalent Codroy Group of Western Newfoundland. In at least four localities on the northeast coast of the Port au Port Peninsula of Newfoundland (Lead Cove, Mistaken Cove, and Aguathuna Quarries east and west) the Big Cove Formation is exposed in apparent sinkholes in Middle Ordovician limestones. At these localities, the rhynchonelliform brachiopods Martinia galataea and M. thetis, which are characteristic of the youngest faunal zone, occur below rocks containing fossils of a slightly older faunal zone. Resolution of the anomaly is based on several observations: 1) the narrow geographic area of karst features with limestones of the Big Cove Formation filling those features; 2) the presence of these brachiopods and other faunal elements in the crevices and cavities in the Ordovician limestone; and 3) the haphazard orientations of the faunal elements with none preserved in life position. Furthermore, comparison of old and new photos at Aguathuna Quarry east indicates that the karst features in the Ordovician limestone are more extensive and more three dimensionally complex than previously recognized, and that the entire deposit of youngest faunal zone fossils filled in crevices and cavities below the rocks with the older fauna after the deposition of the younger fauna. Seismic activity probably opened the blocked crevices and cavities of the complex system and storms probably swept the younger fauna into those crevices and cavities. Further study is planned to fully resolve the anomaly.

Geological Society of America Abstracts with Programs. Vol. 52, No. 2

doi: 10.1130/abs/2020SE-343216

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