The St. George Group (Lower Ordovician), western Newfoundland: sedimentology, diagenesis, and cryptalgal structures
Detailed stratigraphic examination was undertaken of the Lower Ordovician Isthmus Bay, Catoche, and Aguathuna Formations, St. George Group, in western Newfoundland, Lithologic descriptions were grouped into seven peritidal lithotopes, with additional descriptions of the effects of erosion and subaer...
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Memorial University of Newfoundland
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ftmemorialuniv:oai:research.library.mun.ca:6939 2023-10-01T03:57:33+02:00 The St. George Group (Lower Ordovician), western Newfoundland: sedimentology, diagenesis, and cryptalgal structures Pratt, Brian Richard 1979 application/pdf https://research.library.mun.ca/6939/ https://research.library.mun.ca/6939/1/BrianRichardPratt.pdf https://research.library.mun.ca/6939/3/BrianRichardPratt.pdf en eng Memorial University of Newfoundland https://research.library.mun.ca/6939/1/BrianRichardPratt.pdf https://research.library.mun.ca/6939/3/BrianRichardPratt.pdf Pratt, Brian Richard <https://research.library.mun.ca/view/creator_az/Pratt=3ABrian_Richard=3A=3A.html> (1979) The St. George Group (Lower Ordovician), western Newfoundland: sedimentology, diagenesis, and cryptalgal structures. Masters thesis, Memorial University of Newfoundland. thesis_license Thesis NonPeerReviewed 1979 ftmemorialuniv 2023-09-03T06:46:07Z Detailed stratigraphic examination was undertaken of the Lower Ordovician Isthmus Bay, Catoche, and Aguathuna Formations, St. George Group, in western Newfoundland, Lithologic descriptions were grouped into seven peritidal lithotopes, with additional descriptions of the effects of erosion and subaerial exposure, such as hardground formation, evaporite precipitation, and karstification. The vertical oscillation of lithotopes generates sequences rather than ideal shallowing upward cycles. These sequences show that the continental shelf in western Newfoundland, in Lower Ordovician time, was a patchwork of low-relief islands and banks whose character differed geographically and changed with time, as the shelf slowly subsided. Slight uplift and subaerial exposure of the shelf occurred at the end of the Lower Ordovician, resulting in irregular erosion. -- Cryptalgal structures of very diverse character are related to environmental and biological parameters that interacted in a complex way. Laminated structures, stromatolites and cryptalgal laminites, formed in inter- and supratidal areas areas characterized by the episodic addition of sediment. Thrombolite mounds were common in the subtidal zone, where sedimentation onto algal mats resulted in unlaminated microstructure. In places, sponges, primitive corals and the 'calcareous' algae Renalcis contributed to their framework. These mounds are ecologic reefs of surprising complexity, supporting a benthic flora and fauna of all major trophic groups occupying most niches. These reefs occur in the transition period from algal-dominated bioherms to metazoan-dominated bioherms of the later Phanerozoic. Cryptalgal microstructures can be separated into a number of recurring types and a classification is proposed that can be amended to include types not recognized in the St. George. 'Calcareous' algae such as Girvanella and Renalcis are interpreted to be diagenetic taxa resulting from the calcification of blue-green algae. -- The calcareous sediments of the St. George underwent ... Thesis Newfoundland Memorial University of Newfoundland: Research Repository |
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Memorial University of Newfoundland: Research Repository |
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English |
description |
Detailed stratigraphic examination was undertaken of the Lower Ordovician Isthmus Bay, Catoche, and Aguathuna Formations, St. George Group, in western Newfoundland, Lithologic descriptions were grouped into seven peritidal lithotopes, with additional descriptions of the effects of erosion and subaerial exposure, such as hardground formation, evaporite precipitation, and karstification. The vertical oscillation of lithotopes generates sequences rather than ideal shallowing upward cycles. These sequences show that the continental shelf in western Newfoundland, in Lower Ordovician time, was a patchwork of low-relief islands and banks whose character differed geographically and changed with time, as the shelf slowly subsided. Slight uplift and subaerial exposure of the shelf occurred at the end of the Lower Ordovician, resulting in irregular erosion. -- Cryptalgal structures of very diverse character are related to environmental and biological parameters that interacted in a complex way. Laminated structures, stromatolites and cryptalgal laminites, formed in inter- and supratidal areas areas characterized by the episodic addition of sediment. Thrombolite mounds were common in the subtidal zone, where sedimentation onto algal mats resulted in unlaminated microstructure. In places, sponges, primitive corals and the 'calcareous' algae Renalcis contributed to their framework. These mounds are ecologic reefs of surprising complexity, supporting a benthic flora and fauna of all major trophic groups occupying most niches. These reefs occur in the transition period from algal-dominated bioherms to metazoan-dominated bioherms of the later Phanerozoic. Cryptalgal microstructures can be separated into a number of recurring types and a classification is proposed that can be amended to include types not recognized in the St. George. 'Calcareous' algae such as Girvanella and Renalcis are interpreted to be diagenetic taxa resulting from the calcification of blue-green algae. -- The calcareous sediments of the St. George underwent ... |
format |
Thesis |
author |
Pratt, Brian Richard |
spellingShingle |
Pratt, Brian Richard The St. George Group (Lower Ordovician), western Newfoundland: sedimentology, diagenesis, and cryptalgal structures |
author_facet |
Pratt, Brian Richard |
author_sort |
Pratt, Brian Richard |
title |
The St. George Group (Lower Ordovician), western Newfoundland: sedimentology, diagenesis, and cryptalgal structures |
title_short |
The St. George Group (Lower Ordovician), western Newfoundland: sedimentology, diagenesis, and cryptalgal structures |
title_full |
The St. George Group (Lower Ordovician), western Newfoundland: sedimentology, diagenesis, and cryptalgal structures |
title_fullStr |
The St. George Group (Lower Ordovician), western Newfoundland: sedimentology, diagenesis, and cryptalgal structures |
title_full_unstemmed |
The St. George Group (Lower Ordovician), western Newfoundland: sedimentology, diagenesis, and cryptalgal structures |
title_sort |
st. george group (lower ordovician), western newfoundland: sedimentology, diagenesis, and cryptalgal structures |
publisher |
Memorial University of Newfoundland |
publishDate |
1979 |
url |
https://research.library.mun.ca/6939/ https://research.library.mun.ca/6939/1/BrianRichardPratt.pdf https://research.library.mun.ca/6939/3/BrianRichardPratt.pdf |
genre |
Newfoundland |
genre_facet |
Newfoundland |
op_relation |
https://research.library.mun.ca/6939/1/BrianRichardPratt.pdf https://research.library.mun.ca/6939/3/BrianRichardPratt.pdf Pratt, Brian Richard <https://research.library.mun.ca/view/creator_az/Pratt=3ABrian_Richard=3A=3A.html> (1979) The St. George Group (Lower Ordovician), western Newfoundland: sedimentology, diagenesis, and cryptalgal structures. Masters thesis, Memorial University of Newfoundland. |
op_rights |
thesis_license |
_version_ |
1778529078909861888 |