Shale-Facies Microfossils from the Proterozoic Bylot Supergroup, Baffin Island, Canada
Organic-walled microfossils are reported from the Borden Rift Basin of northern Baffin Island and Bylot Island. The diverse assemblage, obtained by palynological acid maceration, comprises 39 taxa and occurs in fine-grained siliciclastic and carbonate units from all but the two lowermost formations...
| Published in: | Journal of Paleontology |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Cambridge University Press (CUP)
1994
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1017/s0022336000062314 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022336000062314 |
| Summary: | Organic-walled microfossils are reported from the Borden Rift Basin of northern Baffin Island and Bylot Island. The diverse assemblage, obtained by palynological acid maceration, comprises 39 taxa and occurs in fine-grained siliciclastic and carbonate units from all but the two lowermost formations of the Bylot Supergroup; their age is bracketed between 1,270 and 750 Ma. Of 307 samples analyzed from all parts of the basin, 133 yielded identifiable remains. The microbiota comprises the following taxa: Siphonophycus septatum, S. robustum, S. rugosum n. comb., S. kestron, S. capitaneum, Pellicularia tenera, Polythrichoides lineatus, Obruchevella valdaica, Karamia ? sp., opaque filaments, Oscillatoriopsis spp., Palaeolyngbya sp., Arctacellularia tetragonala n. comb., A. ellipsoidea, Chlorogloeaopsis contexta n. comb., C. kanshiensis n. comb., Navifusa bacillaris n. comb., N. majensis, N. actinomorpha n. comb., Leiosphaeridia minutissima, L. tenuissima, L. crassa, L. jacutica, L. ternata, Lophosphaeridium granulatum, Valeria lophostriata, Pterospermopsimorpha insolita, Eomicrocystis elegans, E. malgica, Symplassosphaeridium spp., Synsphaeridium spp., Satka squamifera, Satka spp., Coneosphaera arctica n. sp., Coneosphaera sp., Spumosina rubiginosa , and Fabiformis baffinensis n. sp. The taxon Palaeocalothrix divaricatus , present in some macerates, is possibly a modern fungal contaminant. Abundance and taxonomic diversity varies considerably between formations and environments, with the Arctic Bay Formation exhibiting the greatest productivity and species diversity of the seven formations studied, and the transgressive muddy shelf deposits being the most productive of the 11 environments recognized. This microfossil assemblage of predominantly planktonic species has distinctive taxa in common with Middle to Late Riphean sequences in Siberia (Lakhanda and Miroedikha Groups, ca. 950 to 850 Ma), the lower part of the Thule Group (< 1,270 Ma) in northwest Greenland, the Fury and Hecla Group in western Baffin Island, ... |
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