Sedimentology and depositional environment of the middle Cambrian Manuels River Formation in the type locality at Conception Bay South, Newfoundland, Canada

• Main Author: Austermann, Gregor
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2016
• Subjects: 550; 550 Earth sciences; Newfoundland
• Online Access: https://archiv.ub.uni-heidelberg.de/volltextserver/20645/; https://archiv.ub.uni-heidelberg.de/volltextserver/20645/1/PhD_Austermann_2016_final_PDFA.pdf; https://doi.org/10.11588/heidok.00020645; https://nbn-resolving.org/urn:nbn:de:bsz:16-heidok-206458

A detailed bed-by-bed study of fossiliferous, marine, grey to black shales of the middle Cambrian (Drumian, Cambrian Series 3) Manuels River Formation along its type locality in Newfoundland, Canada, was carried out and provides insight into the sedimentology, depositional environment, palaeogeography and climatology of the area. The formation was deposited on the microcontinent Avalonia, the largest terrane of the peri-Gondwanan realm situated in temperate latitudes. The partly organic-rich (up to 3.36 % TOC) shales of the succession were deposited mainly conformably under dysoxic conditions. Deposition was controlled by two shallowing trends and occurred below, near and above mean storm- wave base. The contact of the top of the rst shallowing-upward trend in the succession is conformably, whereas the second shallowing-upward trend is truncated by an erosional unconformity, forming the top of the formation. An average sedimentation rate of c. 3.8 m/ Ma is estimated. The clay-mineral composition and illite crystallinity suggest a subsidence of approximately 5.7–6.3 km and a burial temperature of c. 280 °C. The low chlorite/kaolinite ratios indicate a mainly warm semi-humid climate setting at 35°–65° S, with sudden changes to a semi-arid setting. The subsidence, sedimentation rate and depositional environment suggest an Early Ordovician Avalonia-Gondwana separation.