Abstract:After prograding for several hundred kilometres during Middle Cenomanian time, the Dunvegan delta complex in north‐west Alberta and adjacent British Columbia experienced stepwise transgression, commencing at about the Middle to Late Cenomanian boundary. Progressive drowning of the delta complex is recorded by Dunvegan allomembers B and A, each comprised of three simple depositional sequences, bounded by composite subaerial unconformity/flooding surfaces. Each sequence represents an array of deltaic depositiona… Show more
“…The delta complex prograded 400 km north‐west to south‐east into the actively subsiding foreland basin of Alberta. It is estimated that the delta had a catchment area of around 100 000 km 2 (Bhattacharya & Walker, 1991; Sageman & Arthur, 1994; Plint, 2000; Bhattacharya & MacEachern, 2009; Hay & Plint, 2020).…”
Palaeodischarge estimation is largely undertaken within fluvial settings. However, there are limited palaeodischarge estimates specifically from delta deposits, despite their significance globally. Estimating water palaeodischarges for deltas using catchment-based approaches developed using data from fluvial settings requires estimating parameters from the rock record (for example, palaeotemperature, palaeoslope and palaeorelief). These may be difficult to determine, leading to under-estimation or over-estimation of palaeodischarge values due to differences in process-form relationships between alluvial rivers and deltas. When a sediment-conveying fluvial channel enters a standing body of water, delta lobes develop through repeating mouth bar deposition due to flow deceleration, forming a deltaic morphology with distributary channel networks that differ morphologically from those developed in unidirectional flowing alluvial rivers. This study provides empirical relationships determined across five climate regions, using 3823 measurements of distributary channel width from 66 river deltas alongside the trunk river bankfull discharge that feeds into the entire delta, using a hydraulic geometry scaling approach. Empirical relationships are developed from the global delta dataset between bankfull discharge and catchment area (Q b -A), and bankfull discharge and median distributary channel width (Q b -W med ). These empirical relationships produce very strong statistical correlations, especially between Q b and W med , across different climate regions (Q b = 0.34 W med 1.48 , R 2 = 0.77). However, both Q b -A and Q b -W med relationships have outliers that may be explained by particular hydrological or geomorphic conditions. These new empirical relationships derived from modern systems are then applied to Cretaceous outcrops (Ferron Sandstone and Dunvegan Formation). The comparatively simple scaling relationships derived here produced palaeodischarge estimates within the same order of magnitude as palaeodischarge values previously obtained using existing, more complex approaches. This study contributes to source-to-sink investigations by enabling palaeodischarge estimates that intrinsically account for climate impacts on channel geometry at the time of deposition, using measurements of channel width or catchment area of a deltaic outcrop.
“…The delta complex prograded 400 km north‐west to south‐east into the actively subsiding foreland basin of Alberta. It is estimated that the delta had a catchment area of around 100 000 km 2 (Bhattacharya & Walker, 1991; Sageman & Arthur, 1994; Plint, 2000; Bhattacharya & MacEachern, 2009; Hay & Plint, 2020).…”
Palaeodischarge estimation is largely undertaken within fluvial settings. However, there are limited palaeodischarge estimates specifically from delta deposits, despite their significance globally. Estimating water palaeodischarges for deltas using catchment-based approaches developed using data from fluvial settings requires estimating parameters from the rock record (for example, palaeotemperature, palaeoslope and palaeorelief). These may be difficult to determine, leading to under-estimation or over-estimation of palaeodischarge values due to differences in process-form relationships between alluvial rivers and deltas. When a sediment-conveying fluvial channel enters a standing body of water, delta lobes develop through repeating mouth bar deposition due to flow deceleration, forming a deltaic morphology with distributary channel networks that differ morphologically from those developed in unidirectional flowing alluvial rivers. This study provides empirical relationships determined across five climate regions, using 3823 measurements of distributary channel width from 66 river deltas alongside the trunk river bankfull discharge that feeds into the entire delta, using a hydraulic geometry scaling approach. Empirical relationships are developed from the global delta dataset between bankfull discharge and catchment area (Q b -A), and bankfull discharge and median distributary channel width (Q b -W med ). These empirical relationships produce very strong statistical correlations, especially between Q b and W med , across different climate regions (Q b = 0.34 W med 1.48 , R 2 = 0.77). However, both Q b -A and Q b -W med relationships have outliers that may be explained by particular hydrological or geomorphic conditions. These new empirical relationships derived from modern systems are then applied to Cretaceous outcrops (Ferron Sandstone and Dunvegan Formation). The comparatively simple scaling relationships derived here produced palaeodischarge estimates within the same order of magnitude as palaeodischarge values previously obtained using existing, more complex approaches. This study contributes to source-to-sink investigations by enabling palaeodischarge estimates that intrinsically account for climate impacts on channel geometry at the time of deposition, using measurements of channel width or catchment area of a deltaic outcrop.
“…Across its broad latitudinal extent, the WIS would have had multiple fluvial systems discharging into the basin, predominantly from the western coast where fluviodeltaic systems transported clay-rich sediment and terrestrial organic matter from the rising Sevier mountains (e.g. Bhattacharya and Tye, 2004;Hay and Plint, 2020;Li et al, 2015;Plint, 2000), but also from the east (Elderbak et al, 2014).…”
“…The delta complex prograded 400 km NW to SE into the actively subsiding foreland basin of Alberta. It is estimated that the delta had a catchment area of around 100000 km 2 (Bhattacharya & Walker, 1991;Sageman & Arthur, 1994;Bhattacharya & MacEachern, 2009;Plint, 2000;Hay & Plint, 2020).…”
Paleodischarge estimation is largely undertaken within fluvial settings, and there are limited paleodischarge estimates specifically from delta deposits, despite their significance globally. Making water paleodischarge estimates for deltas using catchment-based approaches developed using data from fluvial settings requires estimation of parameters from the rock record (e.g. paleotemperature, paleoslope, paleorelief) that may be difficult to determine, and may lead to under- or over-estimation of paleodischarge values due to differences in process-form relationships between alluvial rivers and deltas. When a sediment-conveying fluvial channel starts to debouch into a standing body of water, delta lobes develop through repeating mouth bar deposition due to flow deceleration, forming a deltaic morphology with distributary channel networks that differ morphologically from those developed in unidirectional flowing alluvial rivers. This study provides empirical relationships determined across five climate regions, using 3823 measurements of distributary channel width from 66 river deltas alongside their bankfull discharge, by applying the concept of hydraulic geometry. Empirical relationships are developed from the global delta dataset between bankfull discharge and catchment area (Qb-A) and also bankfull discharge and distributary channel width (Qb-w). These empirical relationships produce very strong statistical correlations, especially between Qb and w, across different climate regions (Qb = 0.34w1.48, R2 = 0.77). However, both Qb-A and Qb-w relationships have outliers that may be explained by particular hydrological or geomorphic conditions. These new empirical relationships derived from modern systems are applied to Cretaceous outcrops (Ferron Sandstone, Dunvegan and McMurray formations). The comparatively simple scaling relationships derived here produced paleodischarge estimates within the same order of magnitude as the paleodischarge values derived from existing, more complex approaches. Our study contributes to source-to-sink investigations by enabling paleodischarge estimates that intrinsically account for climate impacts on channel geometry at the time of deposition, using measurements of channel width or catchment area of a deltaic outcrop.
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