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TitleFirst-cycle sand supply and the evolution of the eastern Canadian continental margin: insights from Pb isotopes in the Mesozoic Scotian Basin
AuthorBlowick, A; Pe-Piper, G; Piper, D J WORCID logo; Zhang, Y; Tyrrell, S
SourceGeological Society of America Bulletin vol. 133, 2020 p. 1301-1319, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20200099
PublisherGeological Society of America
Mediapaper; on-line; digital
File formatpdf; html
ProvinceEastern offshore region; Nova Scotia; Newfoundland and Labrador; New Brunswick; Prince Edward Island; Quebec
NTS1; 2; 3; 10; 11; 12; 13; 20; 21; 22; 23
AreaAtlantic Ocean; Gulf of St. Lawrence
Lat/Long WENS -70.0000 -51.0000 55.0000 42.0000
Subjectssedimentology; tectonics; Science and Technology; Nature and Environment; continental margins; sedimentary basins; depositional history; provenance; sediment transport; paleodrainage; depositional cycles; isotopic studies; radioisotopes; lead isotope ratios; detrital minerals; feldspar; zircon; tectonic history; rifting; crustal uplift; faults; exploration wells; source rocks; bedrock geology; lithology; sedimentary rocks; sandstones; Scotian Basin; Atlantic Continental Margin; Labrador Rift; Appalachian Province; Appalachian Orogen; Canadian Shield; Grenville Orogen; Cabot Fault; Ancestral St. Lawrence River; Ancestral Sable River; Ancestral Banquereau River; Phanerozoic; Mesozoic; Cretaceous; Jurassic
Illustrationsgeoscientific sketch maps; schematic sections; bar graphs; tables; plots; stratigraphic charts; pie charts
Released2020 09 10
AbstractProvenance analysis provides a powerful means to understand, connect, and reconstruct source-to-sink systems and Earth surface processes, if reliable toolkits can be developed, refined, and applied. Deciphering sediment routing to the Scotian Basin, offshore eastern Canada, is marred by sedimentary recycling but is critical to understanding the evolution of the Canadian margin in response to the evolving Labrador rift. In this study, Pb isotopes in detrital K-feldspars were fingerprinted in 13 wells across the Scotian Basin to track first-cycle sand supply. Unlike previous approaches, which utilized less labile proxies such as zircon, detrital K-feldspars are unlikely to survive multiple sedimentary cycles. The Pb-isotopic data reveal a dynamic seesaw effect between hinterland sources across the Jurassic-Cretaceous boundary, reflecting the complex interplay between the northward propagation of uplift along the rising Labrador rift flank and the reactivation of fault systems in the lower drainage basin. Pb isotopes in K-feldspar record progressively increasing long-distance supply from eastern Labrador, as early as the Callovian in the central basin, alongside diminishing but persistent local sourcing from adjacent Appalachian terranes. Comparison with more resilient mineral proxies, notably zircon, appears to confirm recycling in the lower drainage basin and highlights the limitations of using a single mineral proxy in isolation. This case study serves as an example of the growing potential of multiproxy provenance toolkits not only to decipher sediment-routing corridors in paleodrainage systems, but to better define and connect the drivers, mechanisms, and spatial and temporal ranges of Earth surface processes and tectonic events.
Summary(Plain Language Summary, not published)
Isotopes of lead in the common mineral feldspar are used to track the sources of reservoir sandstones in the offshore Scotian Basin. This unexpectedly shows a well developed drainage system from the Canadian Shield as early as 165 million year ago, and subsequently important uplift of the Applachians at 150 milliion years ago. Supply from the Canadian Shield became dominant at about 110 million years ago. The study provides new insights into the tectonic evolution of Atlantic Canada in this time frame when the main petroleum reservoir sandstones were deposited.

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