An Update on the Investigation into the Stratigraphy of the Hudson Bay Area and Sedimentology of Local Coal Deposits Jason Berenyi Berenyi, J. (2010): An update on the investigation into the stratigraphy of the Hudson Bay area and sedimentology of local coal deposits; in Summary of Investigations 2010, Volume 2, Saskatchewan Geological Survey, Sask. Ministry of Energy and Resources, Misc. Rep. 2010-4.2, Paper A-11, 9p. Abstract In 2009 and 2010, Goldsource Mines Inc. (Goldsource) continued to utilize its proprietary geophysical interpretation methods to discover and delineate deposits on its Border coal project in the Hudson Bay area. The company has drilled over 140 holes on the property and has discovered 17 coal deposits, some with cumulative coal intersections up to 126.5 m in true thickness. In the summer of 2010, Ministry of Energy and Resources’ staff continued to study the depositional history of the strata hosting these coal discoveries. Over the past two summers, Ministry staff have logged a total of 103 drill holes, focussing attention around the largest discoveries and to areas with the greatest well control. The goal of the 2010 study was to acquire sufficient data to build a preliminary 3-D geological model of one or more of the coal deposits. Detailed core descriptions and geophysical well-log correlations provided the basis for the interpretations. Keywords: Hudson Bay, Chemong, Pasquia, coal, sub-basin, karsting, subsidence, Colorado Group, Mannville, Cantuar, Success, Devonian, Dawson Bay, Red Beds, Ashern, Interlake. 1. Introduction This paper is an update of the work conducted in the Hudson Bay area in 2009 and 2010. For a more complete overview of the project please refer to Berenyi et al. (2009). Between June and August 2010, Saskatchewan Ministry of Energy and Resources’ staff continued with the detailed core logging program initiated in the summer of 2009. Figure 1 illustrates drill-hole locations on the Border project and locations of coal discoveries as of September 2010. The original focus of the program was to identify and correlate the regional stratigraphic units bounding the coal- bearing formation. In 2010, attention was focussed on areas that were delineated by the highest concentration of drill holes, in order to facilitate the development of a 3-D model. Lithologic core logging was conducted with the assistance of down-hole gamma and neutron geophysical logs. The vast majority of coal intersected in the drill holes was sampled by the company for analytical testing prior to logging by Ministry staff. When minor amounts of centimetre-scale coal fragments were present, they were not logged in detail, as they were not known to be representative of the unit as a whole. 2. Update on Local Stratigraphy Each of the stratigraphic formations described by Berenyi et al. (2009) was encountered again in 2010, with much the same frequency. In addition to these units, a few deeper holes drilled in the winter of 2009/2010 intersected lower stratigraphic units of Devonian and Silurian strata (Figure 2). Descriptions of the Ashern Formation and Interlake Group are provided below. a) Interlake Group The Silurian Interlake Group is present in four holes with thicknesses in excess of 90 m. The relatively few occurrences of these units made formational correlations difficult. Based on regional correlations, the uppermost strata of the Interlake Group are interpreted as being part of the Cedar Lake Formation. The units are dominated by pale yellow-grey dolomitic framestones, primarily composed of Favosites corals and stromatoporoids, with lesser rugose corals and crinoids, all being infilled with a microcrystalline dolomite matrix. These rock types correspond Saskatchewan Geological Survey 1 Summary of Investigations 2010, Volume 2 m E m E m E m E m N m Niska 107 Niska 108 m N m Pasquia 96 m N m Pasquia 97 Pasquia 98 Pasquia 05 Pasquia 02 m N m N m Chemong 03 Chemong 100 Chemong 06 Chemong 107 Chemong 20 m N m m N m Split Leaf 39 m N m m N m Drill-hole Locations and Carbonaceous Interval Thickness >0 to 5 m N m m N m >5 to 10 Split Leaf 114 >10 to 25 Road km m N m N m Leaf Lake m E m E m E m E m E Figure 1 - Base map showing the location of Goldsource drill holes. Red box on inset map outlines the study area. Sub-basins modelled in 2010 are circled in red. Saskatchewan Geological Survey 2 Summary of Investigations 2010, Volume 2 very well with descriptions of the Cedar Lake WESTGATE Formation provided by Steam (1956), Jamieson (1979), VIKING / NEWCASTLE ALBIAN JOLI FOU and Jin et al. (1999). Below these units are very fine- SPINNEY HILL COLONY grained dolomitic strata that are finely laminated and PENSE McCLAREN WASECA SPARKY locally interbedded with argillaceous laminae and algal GENERAL PETROLEUMS LOWER CANTUAR REX mats. These units may be correlative to the East Arm LLOYDMINSTER MANNVILLE CUMMINGS CRETACEOUS 111 DINA Formation in Manitoba (Steam, 1956), but too few MESOZOIC APTIAN 122 BARREMIAN intersections were available for a definitive correlation. HAUTERIVIAN VALANGINIAN The Ashern Formation unconformably overlies the BERRIASIAN 142 SUCCESS S2 (INSINGER) TITHONIAN 150 Interlake Group. KIMMERIDGIAN 155 OXFORDIAN UPPER 157 JURASSIC b) Ashern Formation (Elk Point Group) CALLOVIAN 161 The lower Middle Devonian Ashern Formation is the BATHONIAN basal unit of the Elk Point Group (Baillie, 1951), and is 166 JURASSIC MIDDLE unconformably overlain by the Winnipegosis BAJOCIAN JURASSIC 174 Formation. In the project area, the Ashern Formation AALENIAN 178 TOARCIAN was observed in the Niska 108, Pasquia 02, Pasquia 05 LOWER PLIENSBACHIAN SINEMURIAN JURASSIC HETTANGIAN 200 southwest, and the Chemong 06 areas, but was UPPER RHAETIAN TRIASSIC NORIAN TRIASSIC CARNIAN 237 recognized in only five of the 103 holes logged, MIDDLE LADINIAN TRIASSIC ANISIAN 244 averaging approximately 9 m in thickness (Figure 1). It LOWER TRIASSIC SCYTHIAN 253 consists mainly of finely crystalline, non-fossiliferous, PERMIAN dolomitic mudstone with a minor and variable amount 300 of silt. The unit has a distinctive, dominantly pervasive, PENNSYLVANIAN pale orange-brown to deep orange-red colour. No 313 original depositional structures are visible, but the base of the Ashern Formation is commonly brecciated with CHESTERIAN abundant millimetre- to centimetre-scale angular 329 lithoclasts of dolomitic mudstone. MERAMECIAN 334 3. Preliminary Modelling OSAGIAN MISSISSIPPIAN 351 CARBONIFEROUS All images of sub-basins in this report were captured from 3-D models constructed in Paradigm™ GOCAD® KINDERHOOKIAN 360 2009.2. Four deposit areas (sub-basins) were modelled by extending surfaces through well markers at drill-hole FAMENNIAN locations, which were derived from stratigraphic 373 correlations made by the author. All surfaces shown UPPER DEVONIAN represent the modelled base of the designated FRASNIAN formation (with the exception of the surface named PALEOZOIC ‘carbonaceous top’). Poor recovery of the overlying 383 MANITOBA SOURISSOURIS RIVER RIVER GROUP 1ST RED BED formations, and extensive sampling of the coal by DAWSON BAY ND GIVETIAN 2 RED BED Goldsource, meant most carbonaceous contacts were DEVONIAN PRAIRIE MIDDLE ELK DEVONIAN EVAPORITE not present at the time of logging. As a result, 387 POINT GROUP WINNIPEGOSIS EIFELIAN carbonaceous intervals were modelled from data 394 ASHERN DALEJAN provided by Goldsource. ‘Carb top’ and ‘carb bottom’ LOWER EMSIAN 409 DEVONIAN PRAGIAN represent the start and end of any carbonaceous-bearing LOCHKOVIAN 418 UPPER SILURIAN LUDFORDIAN unit including all mineral partings. Since most holes GORSTIAN 424 SILURIAN HOMERIAN LOWER SHEINWOODIAN within these sub-basins were not drilled deep enough to TELYCHIAN INTERLAKE SILURIAN AERONIAN RHUDDANIAN 443 GAMACHIAN STONEWALL intersect underlying Devonian carbonates, the surfaces RICHMONDIAN STONY MOUNTAIN for the Winnipegosis and Dawson Bay formations were 447 UPPER MAYSVILLIAN commonly projected directly below the deepest drill ORDOVICIAN BIG HORN GROUP RED RIVER EDENIAN holes, and as such should be considered as minimum TRENTONIAN WINNIPEG BLACKRIVERIAN 458 depths. The Ashern Formation and Interlake Group MIDDLE CHAZYAN ORDOVICIAN were not included in preliminary modelling due to their ORDOVICIAN LOWER ORDOVICIAN 489 limited occurrences. Orientation and horizontal scale of TREMPEALEAUAN UPPER FRANCONIAN CAMBRIAN DRESBACHIAN 501 DEADWOOD CAMBRIAN the deposits are indicated on each figure. Images of MIDDLE CAMBRIAN sub-basins are tilted toward the reader approximately PRECAMBRIAN + + + + + PRECAMBRIAN 45° from horizontal, and a three-times vertical Figure 2 - Stratigraphic correlation chart listing the units exaggeration has been applied, to better illustrate relief. encountered and their respective ages. Note: Prairie The black mesh lines show locations of control points Evaporite Formation is not present in project area. within the basins and serve to indicate changes in relief. Relief is also illustrated by shading produced by a eastward sun angle at 45° to the horizon. Saskatchewan Geological Survey 3 Summary of Investigations 2010, Volume 2 The Pasquia 02 (PQ2) sub-basin model has the highest concentration of control points, incorporating 17 vertical holes and one deviated hole on the east side of the sub-basin, angled at -55°, and drilled due west underneath the deposit (Figure 3). The tight borehole spacing allows for several inferences to be drawn from the preliminary model. A minimum basin depth can be inferred from a hole, located in the center of the deposit, which was drilled to 200 m below surface and did not intersect the Devonian carbonate contact. For holes that did reach the Devonian carbonate, the Dawson Bay Formation was the first unit encountered, commonly followed by the Winnipegosis Formation. The Souris River Formation was not present in the project area. The PQ2 was the only area where the Success Formation was present in sufficient frequency to correlate throughout most parts of the deposit. The Cantuar Formation projection suggests a small ridge may be running from the northwest to the southeast across the centre of the PQ2 (Figure 3d).