Tectonic, eustatic and climatic controls on marginal-marine sedimentation across a flexural depocentre: paddy member of peace river formation (late albian), western Canada foreland basin

• Main Authors: A. Guy. Plint, Jessica R. Krawetz, Robin A. Buckley, Kathleen M. Vannelli, Ireneusz. Walaszczyk
• Format: Other Non-Article Part of Journal/Newspaper
• Language: unknown
• Published: 2018
• Subjects: albian; alluvial; clastic sedimentation; climate-change; cretaceous; lagoonal; sea-level change; shallow marine; tectonics; western Canada foreland basin; British Columbia; Canada; Peace River
• Online Access: https://figshare.com/articles/journal_contribution/Tectonic_eustatic_and_climatic_controls_on_marginal-marine_sedimentation_across_a_flexural_depocentre_paddy_member_of_peace_river_formation_late_albian_western_Canada_foreland_basin/19823737

In north-central Alberta and adjacent British Columbia, clastic strata of the middle to late Albian Peace River and Shaftesbury formations were deposited in alluvial to shallow-marine environments across the foredeep of the Western Canada Foreland Basin. A high-resolution, log and core-based allostratigraphic framework for the Paddy Member of the Peace River Formation established nine allomembers, PA to PI, bounded by flooding surfaces and apparently equivalent non-marine surfaces. Within the estimated 2 Myr. duration of the Paddy, allomembers allow the evolving palaeogeography and changing relationship between accommodation and sedimentation rates to be analysed on timesteps on the order of 105 years. Paddy strata fill an arcuate depocentre ca 300 km wide, across which the rocks thin eastward from 125 m to ca 5 to 10 m. The northern part of the basin is occupied by muddy, offshore marine deposits that pass abruptly southward into a linear, WSW-ENE-trending body of sandstone deposited in a wave-dominated barrier-strandplain, at least 350 km long. Extending >200 km to the south of the strandplain was a region of shallow brackish to freshwater lagoons and lakes that graded to the SW into alluvial facies. Within the lagoon region, few-m thick, elongate and patchy sandstones represent river-dominated deltas. In allomembers PA to PG, these sandstones are concentrated in the west and south, implying supply from the western Cordillera. In allomembers PH and PI, sandstones are mainly in the east and have a distinctive, quartz-rich composition. They can be correlated eastward into the coeval Pelican Formation, and were sourced probably from the Canadian Shield on the opposite side of the basin. In the western foredeep, alluvial rocks comprise aggradational, unconfined floodplain deposits with ribbon sandstones, dissected, on at least nine separate levels, by palaeovalleys that are confined to the proximal foredeep. Valleys are 10 to 30 m deep, few km wide, and filled with multi-storey channel-bars of pebbly coarse ...