Surficial Geology of the north Lesser Slave Lake area (NTS 83O/North), Alberta
Surficial geological mapping and Quaternary stratigraphic studies in the north Lesser Slave Lake area were continued as part of a multi-year Alberta Geological Survey (AGS) initiative. The surficial studies conducted in this map area (83O/NE, NW) provide crucial information on the surface stratigraphy and deposit characteristics that have implications for exploration of diamonds using drift prospecting and aggregate exploration. The Lesser Slave region of Alberta has been subjected to numerous geological studies (Wynnyk et al., 1963; Vogwill, 1978, 1979; Andriashek, 1986; Scafe and Sham, 1986; Scafe et al., 1986; Edwards and Scafe, 1996); however, efforts mainly focused on the soil surveys, hydrology and the Oligocene gravel deposits that occur in the Swan Hills, south of Lesser Slave Lake. Recent compilation of regional geology provides additional information, although limited at a detailed scale (Tarnocai et al., 2002; Wolfe, 2002; Edwards et al., 2004). Fieldwork was conducted during July and August 2002 and provided continuity with recent mapping programs in the Pelican area (NTS 83P) to the east (Campbell et al., 2002) and Peerless Lake area (NTS 84B) to the north (Fenton et al., 2003a; Paulen et al., 2003a). Particular attention was paid to surface stratigraphy, ice flow indicators and the highly variable nature of the surface sediments. Reconnaissance-level till sampling for diamond indicator minerals and geochemistry were completed and will be released in a future report. Extensive progress was made in unravelling the glacial and post-glacial history of the region.
Physiography of the region is dominated by Lesser Slave Lake, one of Alberta’s largest lakes – 108 km in length and covering 1160 km2. It is a remnant of Glacial Lake Peace, a large glacial lake formed at the foot of the retreating Laurentide Ice Sheet about 11,500 years ago (St-Onge, 1972; Mathews, 1980). Huge volumes of ice widened and flattened the Lesser Slave Lake Valley. North of Lesser Slave Lake, the Heart River Uplands, is a moderate relief highland gently sloping northeastward down to the Utikuma and Wabasca lowlands (Pettapiece, 1986). East of Lesser Slave Lake, Marten Mountain rises sharply and marks the western extent of the Pelican Mountains.
Ice flow history was reconstructed exclusively from streamlined landforms and pebble fabrics. Results indicate multiple phases of ice flow occurred in this region. Ice initially was deflected westward around the Pelican Mountains during the onset of glaciation (Campbell et al., 2001). During glacial maximum, south-southwestward flowing ice overtopped the Pelican Mountains. During the latter stages of glaciation, an ice lobe from the Peace River Valley flowed in a southeasterly direction toward the Utikuma Lowlands (Paulen and McClenaghan, in press). Glacial lakes formed during deglaciation in the Utikuma and Lesser Slave Lake basins. Extensive deposits of hummocky and kettled glaciolacustrine sediments occur southwest of Utikuma Lake, formed from glacial lake sediment deposition on top of stagnating ice. This supraglacial lake drained into the Utikuma Lake basin, which in turn, drained around the eastern edge of the Heart River Uplands and into the Lesser Slave Lake basin. This created several large meltwater channel systems and resulted in extensive sand and gravel deposits along their margins. A large glaciofluvial esker and kame complex was deposited west of Gift Lake. These deposits provide the region with a valuable source of granular aggregate.
Evidence of multiple glacial events in north-central Alberta was discovered along the Willow River, south of Highway 754. At this site, a sandy non-calcareous till underlies several metres of strongly oxidized sand and gravel. Calcareous till deposited during the late Wisconsin glaciation overlies the sand and gravel. This site augments rare exposures and boreholes that document an earlier glaciation (early Wisconsin?) in northern Alberta (Fenton et al., 2003b). On Marten Mountain and ridges above 945 metres above sea level to the east, quartz cobble gravel is commonly found underlying a thin veneer of till. These sediments are similar to the deposits that cap major uplands in Alberta, such as the Swan Hills, Clear Hills and Cypress Hills. Several bedrock outcrops were discovered in the Heart River Uplands and Pelican Mountains. Two coal seams were observed occurring in Wapiti Formation sandstone on the north flank of the Pelican Mountains. The occurrence of these outcrops was previously unknown and imply the necessity to refine the bedrock geology of the region.
Northern Alberta (north of latitude 55°N, or approximately Lesser Slave Lake) is covered by approximately 14 1:250 000-scale map areas that are either unmapped or inadequately mapped with respect to surficial geology, Quaternary stratigraphy, bedrock topography and drift thickness. AGS is currently conducting a multi-year initiative to complete the surficial mapping coverage of northern Alberta. The purpose of this program is to provide the minerals industry with baseline geological information in support of mineral exploration in northern Alberta. Multi-year objectives are to complete the Quaternary geology investigations of northern Alberta, including surficial geology mapping, and stratigraphic and thematic studies. Additional objectives are to provide data and interpretations for northern Alberta, including maps, reports and information sets in electronic and, when required, hard copy.
This CD contains information from the AGS mapping program that focused on the northern portion of the Lesser Slave Lake map area (NTS 83O/N), included are maps of the surficial geology. Interim results have been released through presentations and posters at the 2003 and 2004 Calgary Mineral Exploration Group's Calgary Mining Forum & Alberta Geological Survey Minerals Section Open House (Paulen et al., 2003b; Paulen et al., 2004) and Canadian Quaternary Association Biennial Meeting (Fenton et al., 2003). Subsequent products will contain information on the surface site samples, geochemical analyses and kimberlite indicator mineral content of the collected samples.
Field notes were collected in 2002 using Palm hardware and Pendragon software. This allowed notes to be transferred to an Access database linked to ArcView.
Initial preliminary maps were compiled using 1:60 000 scale air photographs flown in 1986, supplemented by LandSat 7 satellite data. After field checking, the revised surficial maps were digitized into ArcInfo. Following review and editing, the final map products were prepared.
This compact disc constitutes release of maps 312 and 313 prepared for the Alberta Energy and Utilities Board/Alberta Geological Survey (EUB/AGS) by R.C. Paulen, M.M. Fenton and J.G. Pawlowicz. The intent is to make the maps available in a variety of common digital formats to meet the needs of two groups of users: GIS operators and those requiring an exact version of the published map in a readily printable format. GIS files are available in ArcInfo Export (.e00) and shapefile formats. The printer-ready files are in Adobe's Portable Document Format (.PDF).
A brief description follows of each of the formats and how they may be used.
Adobe® Acrobat PDF documents of the published version of the maps allows viewing on any computer capable of running a suitable version of Adobe® Acrobat Reader®.
A freeware version of Adobe® Acrobat Reader® for Microsoft® Windows® is included on the CD-ROM. Adobe® Acrobat Reader® for other platforms are available from Adobe's Web site at www.adobe.com.
To install the software, double-click the "acrobat.exe" file and follow the instructions for installation.
ArcExport (.e00)
Export files were created from coverages in ArcInfo Version 8.3.
Shapefiles provided were created in ArcView version 3.2a. Metadata for each shapefile are contained in html files.
© Her Majesty the Queen in Right of Alberta, 2004
The EUB/AGS and its employees and contractors make no warranty, guarantee or representation, express or implied, or assume any legal liability regarding the correctness, accuracy, completeness, or reliability of this publication. Any digital data and software supplied with this publication are subject to the license conditions (specified in 'Licence Agreement for Digital Products'). The data are supplied on the understanding that they are for the sole use of the licensee and will not be redistributed in any form, in whole or in part, to third parties. Any references to proprietary software in the documentation, and/or any use of proprietary data formats in this release, do not constitute endorsement by the EUB/AGS of any manufacturer's product.
When using information from this publication in other publications or presentations, acknowledgment must be given to the EUB/AGS. The following sample reference format is recommended:
Paulen, R.C., Pawlowicz, J.G. and Fenton, M.M. (2004): Surficial geology of the Utikuma Area, Alberta (NTS 83O/NW); Alberta Energy and Utilities Board, EUB/AGS Map 312, scale 1:100 000.
For more information on the products produced by the EUB/AGS, please contact:
Information Sales
Alberta Energy and Utilities Board
Alberta Geological Survey
4th Floor, Twin Atria Building
4999-98 Avenue
Edmonton, Alberta
T6B 2X3
Canada
Tel: (780) 422-3767
Fax: (780) 422-1918
E-mail: EUB.AGS-Infosales@gov.ab.ca
Web site: www.ags.gov.ab.ca