Planform Recognition and Implications of a Cretaceous-age Continental-scale River Avulsion Node in the Western Interior Basin, Alberta, Canada

2019 ◽  
Vol 89 (7) ◽  
pp. 610-628 ◽  
Author(s):  
Harrison K. Martin ◽  
Stephen M. Hubbard ◽  
Cynthia A. Hagstrom ◽  
Sean C. Horner ◽  
Paul R. Durkin
Keyword(s):  
Oil Sands ◽  
Sedimentary Basins ◽  
Oxbow Lake ◽  
Athabasca Oil Sands ◽  
Deep Time ◽  
Athabasca Oil Sands Region ◽  
Continental Scale ◽  
Mcmurray Formation ◽  
Channel Belt ◽  
Western Interior Basin

Abstract The recognition of an avulsion in the stratigraphic record of an ancient river can provide key insight into its paleoenvironmental setting. In this study, the first planform recognition and delineation of a continental-scale river avulsion node in the deep-time record is used to provide novel insights into the paleogeographic setting for Aptian strata of the Western Interior Basin. Deposits of the Cretaceous McMurray Formation (A2 channel belt) in the Athabasca Oil Sands Region of Alberta, Canada, compose a world-class archive of fluvial–deltaic deposition, captured with a uniquely dense wireline-well-log and drill-core dataset. Despite extensive research on this expansive deposit, however, the depositional setting and paleoenvironmental conditions of the formation have been the subject of long-standing and unresolved debate. In this study, the planform geometry of meander belts characterized by pervasive point-bar and oxbow-lake deposits are examined along a continuous dip-oriented transect > 100 km long, covering > 11,000 km2. The avulsion node documented is linked to three potential causal mechanisms: the presence of the paleobackwater limit, syndepositional salt collapse, or differential erosion and compaction of the substrate associated with an underlying Devonian carbonate escarpment. Although the data compiled do not favor any one of the three proposed mechanisms, each hypothesis potentially provides novel insights into the depositional environment of the McMurray Formation. Notably, the paleobackwater interpretation is consistent with recent seismic geomorphological analysis of the local A2 channel belt that suggested that deposition occurred in the upper reaches of the backwater zone. The results of this work have implications for delineating hydrocarbon-bearing units in the Athabasca Oil Sands, as well as recognizing the record of ancient avulsion nodes in other sedimentary basins.

Salt tectonism and distribution of brackish-water trace fossils in the Cretaceous McMurray Formation, Athabasca Oil Sands, Alberta Foreland Basin

2018 ◽  
Vol 55 (12) ◽  
pp. 1354-1383 ◽  
Author(s):  
Paul L. Broughton
Keyword(s):  
Brackish Water ◽  
Oil Sands ◽  
Foreland Basin ◽  
Trace Fossil ◽  
Food Sources ◽  
Athabasca Oil Sands ◽  
Salt Wedge ◽  
Mcmurray Formation ◽  
Elevated Salinity ◽  
Channel Belt

A proposed salt tectonism-saline seep model provides a novel alternative to the two widely accepted but irreconcilable depositional models for middle McMurray Formation strata of the Lower Cretaceous Athabasca Oil Sands deposit. Established interpretations of a fluvial axial channel belt along the eastern Alberta Foreland Basin contrast with a hundreds-of-kilometres long estuarine marine–fluvial transition zone setting that was characterized by brackish-water trace fossil laden beds. The architecture of a highly sinuous fluvial meander channel belt with bank-full depths of 30–40 m furthermore is not compatible with an estuary having a tens-of-metres thick salt wedge extending hundreds-of-kilometres upstream. This new model proposes that the removal of the underlying 100 m thick Middle Devonian salt section occurred across thousands of square kilometres and resulted in voluminous saline seeps up-section into river channel fills of the middle McMurray Formation. Southward transgression by a Boreal Sea tongue terminated fluvial lower McMurray Formation deposition, and transported brackish-water larvae inland along the tide-impacted backwater length. This zoology was sustained along the fluvial channel belt by the saline seeps that elevated salinity levels in channel muds as the fluvial system dominance reasserted. Brackish-water macroinvertebrates rapidly adapted to new terrestrial food sources in these fluvial channels, precluding the necessity for a salt wedge to have extended inland for hundreds of kilometres. This research presents the first quantitative analysis of the McMurray Formation trace fossil distribution patterns. Quaternary saline surface seep trends are proposed to represent intermittent seepage up-section since the Early Cretaceous.

scholarly journals The Effects of Plume Episodes on PAC Profiles in the Athabasca Oil Sands Region

2021 ◽  
pp. 117014
Author(s):  
Narumol Jariyasopit ◽  
Tom Harner ◽  
Cecilia Shin ◽  
Richard Park
Keyword(s):  
Oil Sands ◽  
Athabasca Oil Sands ◽  
Athabasca Oil Sands Region

scholarly journals Quantification of methane sources in the Athabasca Oil Sands Region of Alberta by aircraft mass balance

2018 ◽  
Vol 18 (10) ◽  
pp. 7361-7378 ◽  
Author(s):  
Sabour Baray ◽  
Andrea Darlington ◽  
Mark Gordon ◽  
Katherine L. Hayden ◽  
Amy Leithead ◽  
...  
Keyword(s):  
Mass Balance ◽  
Oil Sands ◽  
Surface Mining ◽  
Open Pit ◽  
Emission Rates ◽  
Athabasca Oil Sands ◽  
Emissions Inventory ◽  
Athabasca Oil Sands Region ◽  
Major Surface ◽  
Tailings Ponds

Abstract. Aircraft-based measurements of methane (CH4) and other air pollutants in the Athabasca Oil Sands Region (AOSR) were made during a summer intensive field campaign between 13 August and 7 September 2013 in support of the Joint Canada–Alberta Implementation Plan for Oil Sands Monitoring. Chemical signatures were used to identify CH4 sources from tailings ponds (BTEX VOCs), open pit surface mines (NOy and rBC) and elevated plumes from bitumen upgrading facilities (SO2 and NOy). Emission rates of CH4 were determined for the five primary surface mining facilities in the region using two mass-balance methods. Emission rates from source categories within each facility were estimated when plumes from the sources were spatially separable. Tailings ponds accounted for 45 % of total CH4 emissions measured from the major surface mining facilities in the region, while emissions from operations in the open pit mines accounted for ∼ 50 %. The average open pit surface mining emission rates ranged from 1.2 to 2.8 t of CH4 h−1 for different facilities in the AOSR. Amongst the 19 tailings ponds, Mildred Lake Settling Basin, the oldest pond in the region, was found to be responsible for the majority of tailings ponds emissions of CH4 (> 70 %). The sum of measured emission rates of CH4 from the five major facilities, 19.2 ± 1.1 t CH4 h−1, was similar to a single mass-balance determination of CH4 from all major sources in the AOSR determined from a single flight downwind of the facilities, 23.7 ± 3.7 t CH4 h−1. The measured hourly CH4 emission rate from all facilities in the AOSR is 48 ± 8 % higher than that extracted for 2013 from the Canadian Greenhouse Gas Reporting Program, a legislated facility-reported emissions inventory, converted to hourly units. The measured emissions correspond to an emissions rate of 0.17 ± 0.01 Tg CH4 yr−1 if the emissions are assumed as temporally constant, which is an uncertain assumption. The emission rates reported here are relevant for the summer season. In the future, effort should be devoted to measurements in different seasons to further our understanding of the seasonal parameters impacting fugitive emissions of CH4 and to allow for better estimates of annual emissions and year-to-year variability.

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