Lithological Description of Cretaceous Strata in Core from Kennecott Crooked River Kimberlite SK-168-93-1 Drill Hole, East-Central Saskatchewan
Total Page:16
File Type:pdf, Size:1020Kb
Lithological Description of Cretaceous Strata in Core from Kennecott Crooked River Kimberlite SK-168-93-1 Drill Hole, East-central Saskatchewan C.F. Gilboy Gilboy, C.F. ( 1997): Lithological description of Cretaceous strata in core from Kennecott Crooked River Kimherlite SK-l 6B-93- l drill hole, cast-central Saskatchewan; in Summary of Investigations 1997, Saskatchewan Geological Survey, Sask. Energy Mines, Misc. Rep. 97-4. 1. Introduction O. .'i to 1.5 rnrn in diameter. are present in some places (they arc possible Chmulrite.1· burrow infills) as arc very rare sand-filled Chondrites and/or sand-lined Terebel/i11a Several exploration companies, actively searching for burrows up to 3 mm wide. Small ovoid to irregularly diamonds in Saskatchewan, have donated cores of shaped pyrite concentrations, generally surrounded by Phanerozoic strata to the provincial government for brown staining, may he replacements of fowl 1na11er. storage in the Subsurface Geological Laboratory in White, tubular to conical siliceous microfossils up to Regina. These cores arc most useful in improving the about 6 mm long and I mm in diameter, most with a shallow median groove, arc moderately common. Black understanding of the geology of Saskatchewan's specks in the mudstone are probably carboni/.ed plant sedimentary section as, firstly, most are from drill holes remains. Rare honey-coloured fish scales and spines are located in areas that have been sparsely drilled by the also prescnl. Between 43.6 and81.7 mare about 12 pale hydrocarbon industry and, secondly, they arc to moderate brown sideritic layers 4 to IO cm thick. At 81.7 mis an internal cast of a small ( I cm wide) partly essentially continuous. open hinged pelecypod with very line concentric striae; no calcareous shell material is pr,:sc rvcd At 114 m is the The Kennecott core described here is of particular highest hentonite layer, whitish-gr,:y, J cm thick, with interest in that it provides a high-quality, almost biotitc crystals up to 0.2 mm across concentrated at the base. Six more hentonite beds, ranging in thickness from complete lithological profile through Colorado Group I mm to 4 crn, are present above the base of the Millwood rocks at a location (01-04-45-1 OW2) some 110 km Member; several arc burrowed, especially close to their southwest from where they crop out at the north end of top. the Pasquia Hills and 50 km south of the Carrot River outcrops (Figure I). The latter are well known for mid late Cenomanian and Turonian vertebrate fossil assemblages which include an almost complete 7 m long skeleton of Teleorhinus sp., a marine crocodile (Cumbaa and Tokaryk, 1993), and the oldest diverse bird fauna known from North America (Tokaryk et al., 1997). In summer l 997, several outcrops of the Belle Fourche, Second White Specks, and Carlile Formation (following the stratigraphic nomenclature in part proposed by Bloch et al., 1993; sec also McNeil and Caldwell, 1981,andGilboy, 1996)onthcCarrotand Etomami rivers and at the north end of the Pasquia Hills were studied in detail by Dale Leckie (Geological Survey of Canada), Claudia Schroder-Adams (Carleton University), Stephen Cumbaa (Canadian Museum of Nature), John Bloch (geological consultant), and others with a view to establishing detailed micropaleontological control of the exposed strata and further expanding knowledge of their fish and bird faunas. Greg Ludvigson, Brian Witzke, and Tim White (Iowa State Geological Survey) are also researching Mannvillc and Colorado Group rocks in western Manitoba and eastern Saskatchewan lo gain deeper insight into the evolution of the central reaches of the Cretaceous Interior Seaway. K:lorr.c trc s 50 0 50 100 1--~ __ ] 2. Core Description Figure 1 -Location of Kennecott Crooked River Kimber/ite Pierre Shale Formation: Millwood Member SK-16B-93-l and SK-69-93-1 drill holes in east central Saskatchewan and of Colorado Group outcrops sampled 39.9 to 116.3 m Uniform, pale grey mudstones, slightly silty in during 1997 for micropaleontological and vertebratefaunal places. Subhorizontal pyritized black tubular markings, studie.~. 188 Summary of Investigations 1997 Pierre Shale Formation: Pembina Member cement locally well developed. This very fine-grained muddy sandstone, about 30 cm thick. grades down into biotite-rich muddy siltstoncs which are weakly calcareous l 16.3 to 129.5 rn Moderate to dark grey shales containing in places near their top but arc mostly noncalcareous. abundant fi sh remains, pkntiful biotite flakes up to From about 149 to 150.7 m, intense bioturbation 0.5 mm across. subhedral, dear gypsum crystals several (Chondri1es and Terebellina) is evident, and is moderate millimetres across, and white spotting from non to very slight to 15 l. 9 m. Fish remains arc plentiful. calcareous foramimfera tests. Actween 116.3 and l 24.8 rn Aiotite makes up several percent of the rock. This interval are 2'\ well-developed bcntonite seams and four possible of the member is also notable for the 22 bentonitc scams se:uns in poorly recovered core; they range in thickness it contains, eight of which are between 5 and 10 cm thick; from I mm to 15 cm. Bentonites arc absent until 20 cm only the uppermost one at 148. l m (about l mm thick) is above the base of the member where a l mm thick !aver is so poorly preserved that its existence is questionable: the followed by a possible I cm thick seam resting on top of lowest (5 nun thick) is at 152.4 m. A biotite-rich the underlying member. The shales are non-bioturbatcd bentoni te seam at l 51 .9 rn overlies a 5 mm thick bone from 116.5 to l 20.8 m. below which burrowing activity is bed in very fine-grained muddy sandstones. At l 52.2 m very slight, made up essentially of subhoriwntal simple arc poorly sorted, fine-grained sandstones rich in fish branching, commonly pyritized Chondrites. Below bo_nes and with rounded bentonitic clasts of possible fecal 125.8 rn to the base of the memher at l 29.5 m, fish ongm. remains and foraminitcra appear to become rarer whereas recognizable carbonized plant debris is slightly more l 52.6 to 153.6 m :-o cm thick transition wne: very fine-grained conunon. sandstones interbedded with white speckled calcareous siltstones and shales at the top overlie calcareous white speckled shales. A single 5 mm thick bentonitc layer lies Pierre Shale Formation: Gammon Ferruginous at 153.5 m. Member l 29.5 to l 37 .0 m Moderate to dark grey shales. typically with Second White Specks Formation, Keld Member several percent biotite flakes; intervals almost devoid of fish remains and foraminifcra alternate with intervals l 53.6 to 157.6 m Top of the Keld Member is defined by a containing low to moderate abundances. Upper coniact of marked increase in abundance of inoccramid shell member is marked hy 6.5 cm thick siderite layer with fragments, many of which are large and subparallel to small pebbles nr concretions of siderite in underlying bedding, in dark grey slightly silty shales. Between l 54 l mashed up cure. Between the base of this layer and and 156.5 m arc seven pale grey, thin-bedded, impure l JI .J rn arc eight bemonite beds ranging in thickness limestone layers which range in thickness from about 4 to from 0.2 mm 10 4 cm; no further bentonites are present in 1 R cm. The limestones arc rich in fish remains and this member. Very slightly bioturbated (subhorizontal O. l mm diameter calcisphcres; they also contain pyritizcd Chondrites and, possibly, Planolite.1 burrows) inoceramid shell fragments; intcrbeddcd with dark grey from 129.5 to about I 32 m, below which shales are biotite-rich calcareous white speckled shales which also nonbioturbatcd. contain abundant fish remains but only rare inocerarnid fragments; in places, 5 to 10 mm thick shale beds show grading from speckle-free bases to speckle-rich tops. Niobrara Formation (First White Speckled Shales) Between 154 5 and 156.7 mare three bentonite scams ranging in thickness from 2 to 14 cm. Below the lowest of l 37.0 to 144.6 m Moderate to dark grey, nonbio1urbated these scams arc two inoceramid-rich speckled shale beds, calcareous shales containing sparse 10 moderate 62 and l'.l cm 1hick, separated by a l7 cm thick abundance of biolite !lakes, fish remains. and inoccramid-poor speckled shale hed. The interval is foraminifrra; calcareous white specks first observed at essentially nonbioturbated. 137 .3 m. Only two bcntonitc scams present in this formation, at I J7.5 m (0.5 cm thick) and l 38 m ( 1 cm l 57 .6 to l 6J. l m Dark grey calcareous speckled shales with rare thick. bluish, biotite-ric h). lnoceramid shell fragments fish remains and inoceramid fragments: pyrite present. present, but rare, with occurrences of haculitid and Two bentonite seams are present, the upper at l 59.6 mis ostrcid shells even rarer. 15 mm thick, the lower at l 60.6 mis J mm thick; both arc bluish grey. The interval is essentially nonbioturbated. Carlile Formation (Morden Shale) Belle Fourche Formation 144.6 to 146.0 m At 144.6 rn is an abrupt transition from cakareou s to noncalcarcous dark grey. biot i tc~ rich shales; 16~. l to 168.8 m Contact between calcareous speckled and fish remains abundant: probable foraminifcra tests mostly noncalcareous shales is sharp and apparently rare hut locally common. Bentonite layers are absent. conformable. Shales in this interval are black and arc interbcdded with one grain thick siltstones which are sparse (make up less than l pcrccnl of the interval), are Second White Specks Formation, Assiniboine relatively (compared with the shales) rich in fish remains, Member especially scales, contain carbonized plant remains, and are micaceous, with both white mica and biotite 146.0 10 148.0 rn Abrupt transition back into moderate to dark represented.