South Reindeer Lake Quaternary Project: Glaciofluvial Corridors and Reconnaissance-scale Kimberlite Indicator Mineral Sampling (NTS 64D/10, with Parts of 64D/07, /08, /09 and /11) Michelle A. Hanson 1 Information from this publication may be used if credit is given. It is recommended that reference to this publication be made in the following form: Hanson, M.A. (2017): South Reindeer Lake Quaternary project: glaciofluvial corridors and reconnaissance-scale kimberlite indicator mineral sampling (NTS 64D/10, with parts of 64D/07, /08, /09 and /11); in Summary of Investigations 2017, Volume 2, Saskatchewan Geological Survey, Saskatchewan Ministry of the Economy, Miscellaneous Report 2017-4.2, Paper A-10, 25p. This paper is associated with the map separates entitled: Hanson, M.A. (2017): Surficial geology of the Milton Island area, Reindeer Lake (NTS 64D/10, with parts of 64D/07 and /11); 1:100 000-scale preliminary map with Summary of Investigations 2017, Volume 2, Saskatchewan Geological Survey, Saskatchewan Ministry of the Economy, Miscellaneous Report 2017-4.2-(3). Hanson, M.A. and Dixon, D. (in press): Surficial geology of the Bleasdell Lake area (western NTS 64D/09, with part of 64D/08); 1:100 000-scale preliminary map. Abstract As part of the South Reindeer Lake Quaternary project, samples for kimberlite indicator mineral (KIM) analysis were collected from glaciofluvial sediment in the Milton Island area of Reindeer Lake. This paper describes the distribution and characteristics of glaciofluvial corridors in this area and the locations of KIM and pebble samples collected during the 2017 field season. A regional glacial meltwater drainage network existed in the study area during the last deglaciation. Six glaciofluvial corridors were identified, trending southwestward. These corridors are 0.3 to 2 km wide, separated by 10 to 15 km, forming a weakly dendritic pattern, and are characterized by eskers, glaciofluvial plains, kames and kettles, meltwater-scoured bedrock, winnowed and eroded till, and cobble-boulder fields. The lateral boundaries of the corridors are commonly sharp and areas between corridors are largely covered in subglacially deposited till. Nineteen samples of glaciofluvial sediment were collected for KIM analysis. Samples were collected from esker crests, a kame, a glaciofluvial plain, from beaches formed from these deposits, and from glaciofluvial outwash fans. Medium- to coarse-sized sand was targeted, as were facies containing concentrations of heavy minerals, where present. At the time of publication, results from the analysis of the KIM samples were not available, but these results will be added to the Saskatchewan KIM database and the Saskatchewan Mining and Petroleum GeoAtlas once received. Ten samples of pebbles were collected from glaciofluvial sediment, with the intent to determine sediment provenance and dispersal distance of glaciofluvial deposits. Whereas almost all of the pebbles are consistent with the local bedrock geology, many are also consistent with bedrock geology up to 100 km to the northeast, making it difficult to determine glaciofluvial sediment provenance and dispersal distance at this stage of the investigation. Typically, however, dispersal trains within eskers extend up to a maximum of 25 km, and planned analysis of pebble rock types in till as well as fine-fraction geochemical analysis of till in the study area might help determine glacial dispersal distances within the region and aid in the production of a glacial dispersal model for the area. Keywords: kimberlite indicator minerals, KIM, Quaternary, Reindeer Lake, glaciofluvial corridor, drift prospecting, Late Wisconsinan, Reindeer Zone 1. Introduction As part of the South Reindeer Lake Quaternary project, samples for kimberlite indicator mineral (KIM) analysis were collected from glaciofluvial sediment in the Milton Island area of Reindeer Lake (Figure 1). 1 Saskatchewan Ministry of the Economy, Saskatchewan Geological Survey, 1000-2103 11th Avenue, Regina, SK S4P 3Z8 Although the Saskatchewan Ministry of the Economy has exercised all reasonable care in the compilation, interpretation and production of this product, it is not possible to ensure total accuracy, and all persons who rely on the information contained herein do so at their own risk. The Saskatchewan Ministry of the Economy and the Government of Saskatchewan do not accept liability for any errors, omissions or inaccuracies that may be included in, or derived from, this product. Saskatchewan Geological Survey 1 Summary of Investigations 2017, Volume 2 Figure 1 – Lithostructural domainal map of northern Saskatchewan showing the 2017 project area; polygons highlighted in green are inliers of the buried Archean Sask craton. Saskatchewan Geospatial Imagery Collaborative (SGIC) orthophoto shows detailed view of the study area. Saskatchewan Geological Survey 2 Summary of Investigations 2017, Volume 2 The South Reindeer Lake Quaternary project was designed to provide surficial geological data to assist with the assessment of the mineral potential and the application of drift prospecting in the area. Fieldwork for this project was initiated in 2017 and covered the extent of NTS 64D/10 and some adjacent areas in 64D/07, /08, /09 and /11. This project has four main components: 1) Surficial geology mapping at a scale of 1:100 000 and surficial sediment description; 2) Determination of ice-flow directions and chronological reconstruction; 3) Regional-scale till sampling for fine-fraction geochemical analysis, grain size determination and pebble rock type determination; and 4) Reconnaissance-scale KIM sampling. This paper deals mainly with the fourth component, describing the distribution and composition of glaciofluvial sediment and the location of KIM samples collected during the 2017 field season. At the time of publication, results from the analysis of the KIM samples had not been received, but these results will be added to the Saskatchewan KIM database (http://publications.gov.sk.ca/documents/310/96198-Kimberlite%20Indicator%20Minerals.pdf) once available. The rationale for reconnaissance-scale KIM sampling in the area is twofold. First, recent discoveries of KIMs in exposed areas of the Sask craton, such as near Deschambault Lake (Figure 1), have spurred exploration for diamond-bearing kimberlites in the region. The current study area is within the vicinity of several Archean cratons at depth (Corrigan et al., 2005, 2007), the boundaries of which are not well defined, and thus has the potential for diamond-bearing kimberlites. Second, the study area has an abundance of ideal glacial landforms and sediments for reconnaissance-scale KIM sampling. Eskers—long ridges of gravel to sand sediments deposited by meltwater in subglacial channels—are the primary target for KIM sampling. On the Canadian Shield, eskers are very common; in the study area, they are particularly abundant and easily accessible for sampling. 2. Regional Setting a) Bedrock Geology The bedrock geology of the area (Figure 2) is discussed in detail by Maxeiner et al. (2004, 2005, and references therein). The bedrock is part of the Reindeer Zone, which comprises mainly 1.92 to 1.83 Ga subduction-generated arc volcanic and plutonic rocks and marginal basin sedimentary rocks. These rock units are thought to have formed in a Pacific-scale ocean basin, the Manikewan Ocean (Stauffer, 1984), that occupied the region between the Rae- Hearne, Superior, and Sask cratons prior to terminal collision and formation of the 1.8 Ga Trans-Hudson Orogen (Saskatchewan Geological Survey, 2003). These cratons formed the root of the region. The northwestern Reindeer Zone, including the study area, forms a north-northwest–dipping imbricate stack of Paleoproterozoic juvenile arc, sedimentary and plutonic rocks of various ages and tectonic settings that have been metamorphosed to amphibolite facies (Maxeiner et al., 2004). Rocks in the study area are predominantly part of the Lawrence Point (1.92 Ga), Reed Lake (?1.88 to 1.87 Ga), Milton Island (~?1.87 Ga), Duck Lake (~1.87 Ga), and Levesque Point assemblages, and the Sickle/McLennan groups (~1.84 Ga), and include mafic to ultramafic igneous rocks, felsic to intermediate volcanic rocks, pelitic to psammitic turbidites, and derived migmatites (Maxeiner et al., 2004). b) Late Wisconsinan Glacial Chronology Northern Saskatchewan underwent numerous glaciations throughout the Quaternary Period, but it is primarily the record of the last, the Late Wisconsinan, that is well preserved. During the last glaciation, the Laurentide Ice Sheet (LIS) advanced and flowed generally southwestward over Saskatchewan from a dispersal centre in the Keewatin Sector, in Nunavut (Prest et al., 1968; Prest, 1984; Dyke and Prest, 1987; Dyke et al., 2002). Nineteen to 23 thousand calendar years before present (cal. ka BP; ~18.0 14C ka BP2; Mix et al., 2001; Dyke, 2004), at the maximum extent of the LIS, most of Saskatchewan was covered by ice, which would have been greater than 3000 m 2 Because radiocarbon ages are based on the radioactive decay of 14C and the level of atmospheric 14C has not been constant over time, radiocarbon ages need to be calibrated in order to determine an age in calendar years. A radiocarbon age is a fixed age but a calendar age may change based on the calibration curve used. Both ages are reported here for clarity. Calendar years reported are taken directly from referenced publications and have not been recalibrated. Saskatchewan Geological Survey 3 Summary of Investigations 2017,