The deepwater volcaniclastic Mistaken Point Formation in the northeastern Avalon Peninsula: facies, architecture, and detrital (U-PB) zircon provenance

Khatrine, Grace (2024) The deepwater volcaniclastic Mistaken Point Formation in the northeastern Avalon Peninsula: facies, architecture, and detrital (U-PB) zircon provenance. Masters thesis, Memorial University of Newfoundland.

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Abstract

The Mistaken Point Formation (MPF) is a ~400 m-thick late Neoproterozoic siliciclastic-volcaniclastic unit that crops out in the Avalon Zone of Newfoundland Appalanchians and is recognized as one of the world's leading Ediacaran fossil-bearing deep-water successions. The MPF sits at the top of a thick sequence of volcaniclastic submarine fan strata within the Conception Group. These layers were deposited during the transition from a fore-arc or back-arc basin to a potentially foreland basin. Thus, MPF strata can provide insight into whether the basin transformation may have influenced important aspects of the sedimentary environment during the deposition of the MPF. Detailed stratigraphic, petrographic, and facies analysis were integrated, supporting a submarine fan depositional system with two lobe complexes: MPF1 and MPF2. Stratal stacking patterns indicate a “back stepping” lobe abandonment. Examination of facies reveals the presence of ponded turbidites and stratification resembling HCS, which document the gradual confinement of the basin over time. Paleocurrent measurements demonstrate a slight variation in sediment routing directions from S-SE to S-SW. MPF1 detrital zircon ages define a unimodal peak at ca. 650 Ma consisting mostly of Ediacaran to Cryogenian, subordinate peak of Mesoproterozoic and Paleoproterozoic ages, whereas the overlying MPF2 depicts a polymodal distribution with peaks at ca. 600 and 580 Ma comprising mostly Ediacaran ages, less Cryogenian than MPF1, and Mesoproterozoic ages. This research emphasizes the development of the MPF submarine fan system as it undergoes basin transformations. This transformation plays a crucial role in enhancing our understanding of paleogeographic reconstructions of submarine fans. It also provides valuable insights into the evolution of the basin and tectonic processes of Ediacaran strata in the northeastern Avalon Peninsula.

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