Detrital chromite concentrations, nearshore Port au Port Bay, Newfoundland
DOI:
https://doi.org/10.4138/1865Abstract
A nearshore sediment sampling program was undertaken in Port au Port Bay, western Newfoundland. The -objectives of the program were to map the distribution of detrital chromite in the seabed sediments and to evaluate the paleoenvironmental evolution of chromite-bearing sedimentary facies. Bottom sediments were found to be enriched in detrital chromite in an area adjacent to and parallel to the east shore of the bay, south of the mouth of the Fox Island River. During glaciation, chromite from the Lewis Hills ophiolite complex was incorporated in glacial materials. Post-glacial reworking of chromite-bearing sediments by fluvial and marine processes is observed in a number of sedimentary facies: fluvial sediments of the Fox Island River, a large outwash plain and marine-limit delta occurring near the mouth of Fox Island River, an erosional lag blanketing the outwash delta, and emergent and submergent beach terraces bordering a small coastal embayment south of Fox Island River, The relatively low wave energy of the Port au Port Bay area appears, however, to have precluded extensive placer development in all sedimentary facies. RÉSUMÉ Un programme d'éhantillonage des sédiments côtiers fut entrepris dans la baie de Port-au-Port, dans l'ouest de Terre-Neuve. Les buts de ce programme étaient de cartographier la distribution de la chromite détritique dans les sédiments de fonds marin et d'évaluer l’évolution paléo-environnementale des faciès sédimentaires porteurs de chromite. Les sédiments de fond se sont révèles être enrichis en chromite détriiique dans une zone adjacente et parallèle à la côte est de la baie, au sud de l’embouchure de la rivière de file Fox. Pendant la glaciation, la chromite du complexe ophiolitique de Lewis Hills fut incorporée dans les matériaux glaciaires. Le remaniement post-glaciaire des sédiments porteurs de chromite par des processus fluviaux et marins est observé dans un certain nombre de faciès sédimentaires: les sédiments fluviaux de la rivière de Tile Fox, unsandur étenductun delta de contact glaciaire situe près de l'embouchure de la rivière de Tile Fox, un gravier résiduel qui recouvre le sandur et des terrasses marines émergentes et submerges bordant une anse située au sud de la rivière de l'ile Fox. L'énergie relativement basse des vagues de la région de Port-au-Port semble toutefois avoir empêché la formation de placers étendus dans tous les faciès sédiment aires. [Traduit par le journal]Downloads
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