Date of Award
1991
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
The Westphalian A (Pennsylvanian) Boss Point Formation consists of sandstone and mudrock units which developed within an active pull-apart basin (the Cumberland subbasin) in Maritime Canada. The bulk of the formation comprises trough cross-bedded sandstones interpreted as braided river deposits. The rivers flowed from largely felsic igneous provenance areas in the west, toward the region of the present-day Bay of Fundy. Paleocurrents indicate a dominant northeast-directed drainage system, which deviated toward the southeast in the vicinity of Cape Maringouin, about a paleogeographic high related to the penecontemporaneous Harvey-Hopewell Fault.;Intercalated with the sand-dominated fluvial rocks, are fine-grained sandstones, ostracod-bearing limestones and coaly shales deposited in a variety of fluvio-lacustrine settings, including distributary channel, crevasse-splay, deltaic and open lacustrine environments. Rootlet horizons, pedogenic features and rills associated with many of the interbedded sandstones indicate that lake depths were probably shallow, and that lake levels fluctuated frequently.;Paleosols occur widely and formed in areas that were starved of sediment for appreciable periods of time. Paleosol geochemistry indicates a high Al content in all pedogenic materials, consistent with extensive in situ weathering. The abundance of calcrete nodules, suggests a semi-arid climate during the time of sedimentation. Calcrete morphologies include ferroan calcite, crystic plasmic ped material, siltstone aggregates, fragmentary nodules and Mn-rich spherulitic siderites. The paleosols are considered to represent ancient aridisols and vertisols.;At least 8 repetitions of sandstones and mudrocks are recognised through the formation, these defining megacycles as much as 170 m thick. Although faulting may account for the megacycles, it is considered more likely that eustasy was the principal cause for their development. Sandstones were largely deposited during periods of relative eustatic fall, whereas the mudrocks formed during transgressive or high stand periods. Observed stratal relationships are counter to existing published models for fluvial deposition in response to relative sea level change, and modifications are presented based on the Boss Point Formation. The existence of glaciations during the Permo-Carboniferous is well established, suggesting a glacio-eustatic control of the observed stratal geometries, the major glaciation occurring during the Early Pennsylvanian, synchronous with Boss Point Formation sedimentation.
Recommended Citation
Browne, Gregory Hawtrey, "The Sedimentology Of The Boss Point Formation (pennsylvanian), Eastern New Brunswick And Northern Nova Scotia (volumes I And Ii)" (1991). Digitized Theses. 1943.
https://ir.lib.uwo.ca/digitizedtheses/1943