| Title | Linking clinoform trajectory analysis and sequence stratigraphy: improved stratigraphic understanding of the Labrador margin, offshore eastern Canada |
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| Author | Dafoe, L T ;
Dickie, K; Williams, G L |
| Source | GAC-MAC-IAH-CNC-CSPG, Halifax 2022; 2022 p. 79  Open
Access |
| Links | Online - En ligne (Complete volume - volume complet,
PDF, 7.43 MB
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| Image |  |
| Year | 2022 |
| Alt Series | Natural Resources Canada, Contribution Series 20210585 |
| Publisher | Geological Association of Canada |
| Meeting | GAC-MAC-IAH-CNC-CSPG, Halifax 2022; Halifax, NS; CA; May 15-18, 2022 |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Eastern offshore region; Newfoundland and Labrador |
| NTS | 3; 13; 14; 15 |
| Area | Labrador |
| Lat/Long WENS | -63.0000 -54.0000 63.0000 53.0000 |
| Subjects | stratigraphy; sedimentology; Science and Technology; Nature and Environment; systematic stratigraphy; morphology; paleoenvironment; lithostratigraphy; depositional history; tectonic history; Hopedale
Basin; Saglek Basin; Labrador Margin; Markland Formation; Freydis Member; Cartwright Formation; Gudrid Member; Kenamu Formation; Leif Member; Mokami Formation; Saglek Member; Phanerozoic; Cenozoic; Tertiary; Mesozoic; Cretaceous |
| Program | GEM2: Geo-mapping for Energy and Minerals Baffin Region |
| Released | 2022 05 15 |
| Abstract | The concept of a clinoform has been around for decades, but has received renewed attention in its application to stratigraphic studies. These morphological features develop in different depositional
settings, including shorelines, subaqueous deltas, and shelf-edges, with a clinothem corresponding to the body of rock bounded by successive clinoforms. The passive margin of Labrador began forming during rifting in the Cretaceous, with subsequent
seafloor spreading starting in the Maastrichtian and ceasing in the earliest Oligocene. The resultant stratigraphic record includes a number of Late Cretaceous through Pleistocene clinothem units that we have identified and mapped. Focusing on the
Hopedale Basin, where sufficient well and seismic data exist, we combined paleoenvironmental interpretations, biostratigraphic constraints, and seismic data to produce paleogeographic maps and seismic profiles that delineate seven shoreline, five
subaqueous delta, one shelf-edge, and three shelf-edge delta clinothems. Changes in paleoenvironments and clinoform trajectories (relative lateral and vertical movements) were used to define eight second-order sequences, which allowed for refinements
to the Labrador margin lithostratigraphic column and to an improved understanding of tectonic, eustatic, and climatic influences throughout the region's depositional history. Upper Cretaceous shoreline clinothems of the Freydis Member (Markland
Formation) developed during late rift and characterize lowstand and highstand intervals. Subsidence occurred at this time, but a global sea level low in the Cenomanian-Turonian was also likely a major factor during regression. The Gudrid Member
(Cartwright Formation) represents a forced regressive and lowstand interval during the Paleocene to Early Eocene, tied to seafloor spreading, a Selandian eustatic low, and sediment supply driven by the Paleocene-Eocene Thermal Maximum. Kenamu
Formation shales represent a major transgression of the margin in the Early Eocene, with a small shoreline clinothem developed during stillstand. Subsequent Middle Eocene regression formed the Leif Member shoreline clinothem and associated subaqueous
delta and shelf-edge clinoforms, with the Middle Eocene Climatic Optimum possibly contributing to enhanced sediment influx. Subtle subaqueous delta clinothems developed in the Late Eocene and Early Oligocene within the Mokami Formation during
highstand conditions. The Saglek Member of this formation includes three shelf-edge delta clinoform units developed during falling stage and lowstand conditions, and were influenced by the Oi2 glaciation and global sea level fall in the Oligocene,
the Miocene Climate Optimum, and Pliocene-Pleistocene Northern Hemisphere glaciation. This study demonstrates the utility of integrating clinoform trajectory and sequence stratigraphy analyses at second-order scale on a margin that underwent several
major regressive and transgressive events. |
| Summary | (Plain Language Summary, not published)
The offshore Labrador margin formed during plate tectonic extension that started in the Cretaceous, which thinned the continental crust, formed
depocentres for sedimentary rocks to accumulate, and eventually led to formation of the Labrador Sea. The nature of the stratigraphy or layers of rock that built up over time is revised in this study using the mapping of clinoforms, features such as
those formed where a river meets the oceanic realm and results in a delta. The basinward and landward movement of these clinoforms records major regressions and transgressions of the margin over time and can be linked to a sequence stratigraphic
framework. This allows for a new understanding of the rock layers offshore Labrador - a framework that will be valuable in future studies and exploration for energy and mineral resources along the margin. |
| GEOSCAN ID | 329503 |
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