Sedimentology of the Bradore formation, southern Labrador, Newfoundland
The Lower Cambrian Bradore Formation in Southern Labrador consists predominantly of cross stratified subarkoses, with thin beds of conglomerate and siltstone in the basal part. -- The formation is divisible into two members; the lower, named the Blanc Sablon Member, consists of a basal conglomerate...
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| Format: | Thesis |
| Language: | English |
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Memorial University of Newfoundland
1975
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| Online Access: | https://research.library.mun.ca/6880/ https://research.library.mun.ca/6880/1/RAWaring.pdf https://research.library.mun.ca/6880/3/RAWaring.pdf |
| Summary: | The Lower Cambrian Bradore Formation in Southern Labrador consists predominantly of cross stratified subarkoses, with thin beds of conglomerate and siltstone in the basal part. -- The formation is divisible into two members; the lower, named the Blanc Sablon Member, consists of a basal conglomerate and arkosic sandstones and rests unconformably on a Precambrian basement. Intercalated conglomeratic bands are frequent in the lower beds of this member. Thick to medium bedded subarkoses in the upper beds display isolated lenticular and tabular cross bedding and abundant trough cross stratification. The upper, named the L'Anse au Clair Member, consists of thick bedded quartzose sandstones and thin bedded subarkoses containing worm burrows. Here, cross stratification is less common than in the Lower Member and is mostly lenticular. -- Sedimentary textures and structures indicate that the basal conglomerate was formed by a transgression, probably during the early Cambrian. The purity of the sandstone and the form of its grains suggests deposition of material which has been acted upon for prolonged periods of time, in an environment where currents have restricted the accumulation of silt or grains under a certain size. -- Burrowing structures are extremely common and together with the polymodal orientation of trough cross stratification indicates a shallow water, low energy environment for the subarkoses of the Blanc Sablon Member. The facies of the L'Anse au Clair Member represents a tidal flat or beach deposit. |
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