Adam Fraser
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B. Sc. (Honours) Thesis
(PDF - 6.7 Mb)
In the Meguma Supergroup, a series of sandy and shaly intervals formed in a range of depositional environments from deltaic to deepwater. The Lower Ordovician Bluestone Formation in Point Pleasant Park on the Halifax Peninsula is part of the Halifax Group. Prior studies examined the regional geology, micropaleontology, and metamorphism but paid little attention to sedimentology of these outcrops, in part due to the metamorphic overprint that can obscure primary physical sedimentary structures. The goal of this project is to interpret the depositional environment of these sediments and understand their distribution and architecture. Data were collected at outcrops along the Northwest Arm, Black Rock Beach, the Battery, and Sailors' Memorial Road to investigate the geometry and architecture of the studied sections. Data collection includes measuring and logging sections, paleocurrent measurements from such features as tool marks and current ripples, petrographic analysis, scintillometer measurements to create synthetic gamma logs, LiDAR to develop 3D geological models in Polyworks and Petrel, The strata comprise mainly quartz, mica, zircon and tourmaline, and shows five lithofacies. These lithofacies make up a cyclic lithofacies association which is separated by sharp or scoured contacts. Scintillometer analysis showed no apparent relationship to lithology, likely due to the moderate metamorphism throughout the Meguma Supergroup. Interpretation suggested that the lithofacies association is characteristic of the Bouma sequence Ta-e and represents low density turbidites. Current ripples on bedding planes indicate the paleocurrent was towards the northwest. The beds fine and become thinner towards the top of the outcrop and lithofacies like meta sandy-siltstone ripples, and structureless silty slate to slate become more dominant, due to the reduction of sediment supply. Lithofacies and sedimentary structures seen in the outcrop, suggest these sediments were deposited from hypocynal turbidites on the distal overbank and levees of channels.
Pages: 98
Supervisor: Grant Wach