Distribution of Lower Paleozoic Strata in the Vicinity of the Meadow Lake Escarpment, West-Central Saskatchewan F.M. Haid/ Haid!, F.M. (1989): Distribution of Lower Paleozoic strata in the vicinity of the Meadow Lake Escarpment, west-central Sas­ katchewan; in Summary of Investigations 1989, Saskatchewan Geological Survey; Saskatchewan Energy and Mines, Miscel­ laneous Report 89-4. This study was undertaken to provide data necessary to (Figure 1). Stratigraphic correlations of Ordovician and delineate the northern limits of Ordovician and Silurian Silurian carbonates were established using geophysical strata on maps generated for the New Geologic Atlas of logs and drill cuttings. Data from the Cambrian and Or­ Western Canada Sedimentary Basin, and to further on­ dovician elastic sequence are from Paterson (1971) and going research by the author on the Silurian sequence from an ongoing regional study by D.F. Paterson, who in Saskatchewan (Haid!, 1987, 1988). The paper sum­ kindly made available these new data. marizes results from 73 wells in an area encompassing Townships 47 to 64, Range 24W2 to the Alberta border ~ SUBCROP OF INTERLAKE FORMATION SUBCROP OF STONY MOUNTAIN FORMATION ~ [>. <)! SUBCROP OF STONEWALL FORMATION L......:...J SUBCROP OF RED RIVER FORMATION - (HERALD /YEOMAN FORMATIONS) Figure 1 - Suocrop map of Lower Paleozoic caroonatt,s in the study ama. The erosional edge of the Red River Formation defines the Meadow Lake Escarpment, a northwest-facing slope formed by differential erosion of Red River caroonates and Dead· wood/Earlie elastics. The location of cross section A·A' (Figure 2) is shown by a heavy black line. Saskatchewan Geological Survey 125 1. Geologic Setting Meadow lake Escarpment, along the northeast-south­ west curvilinear trend of the erosional edge of the Red Lower Paleozoic strata in Saskatchewan were deposited River Formation (van Hees, 1958). Later transgression on the Interior Platform component of the Western of the sea southwards across the Escarpment resulted Canada Sedimentary Basin (Aitken, in press; Osadetz in deposition of the argillaceous dolomites, dolomitic and Haidl, in press). These deposits encompass the two shales. and minor anhydrites of the Ashern Formation lowermost major unconformity-bounded sequences of (van Hees, 1958; Buller 1958; uppermost beds, Meadow Sloss (1963), the Sauk Sequence and Tippecanoe Se­ Lake Fm., Fuzesy, 1980). At the close of Ashern deposi­ quence. In west-central Saskatchewan, Sauk Sequence tion, the Meadow Lake Escarpment was buried by strata are composed entirely of elastics (Deadwood and Devonian sediments (Figure 2). Earlie Formations) of Middle Cambrian to Early Or­ dovician age. A major unconformity separates these In the northeast corner of the study area (wells in Twp. elastics from the basal elastic unit of the Tippecanoe Se­ 61 and 64, Age. 24W2; Twp. 63, Age. 1W3, Table 1), quence, the Winnipeg Formation (Middle Ordovician), truncation of Devonian and Lower Paleozoic strata oc­ which is present only in the eastern portion of the study curred during the pre-Cretaceous erosion period. In this area (Table 1). The remainder of the Tippecanoe Se­ area, Lower Cretaceous sandstones of the Mannville quence is composed of carbonates of Late Ordovician Group overlie Ordovician carbonates. to Early Silurian age. This carbonate sequence was deposited in the ancestral Williston Basin with northern depositional limits that probably extended well beyond 2. Stratigraphy the study area, but uplift on the northern margin during the pre-Devonian erosion period resulted in substantial a) Deadwood and Earlie Formations truncation of Lower Paleozoic strata (van Hees, 1958, 1964). At the erosional margin of resistant Ordovician Historically, the siltstones, shales, and sandstones which carbonates (Figure 2), more rapid erosion of less resis­ comprise the basal sedimentary sequence in western tant Deadwood/Earlie claS1ics formed a relatively steep Saskatchewan have been assigned to the Deadwood northwest-facing slope, the Meadow Lake Escarpment Formation (Fyson, 1961; Fuzesy, 1980). Recent work by (van Hees, 1958). North of this escarpment, pre­ Paterson (1988; this volume) suggests that the lower por­ Oevonian erosion also removed up to 300 m of Sauk Se­ tion of the sequence is Middle Cambrian in age and cor­ quence strata (van Hees, 1958, 1964). relates with the Earlie Formation defined in eastern Alber­ ta (Pugh, 1971). The remainder of the sequence corre­ Following the initial transgression of Middle Devonian lates with the Deadwood Formation which is assigned a seas, a complex sequence of evaporites. carbonates, Late Cambrian to Early Ordovician age (Paterson, 1988; and elastics (Meadow lake Fm., Fuzesy, 1980; Meadow Lefever et al., 1987; Pugh, 1971) . Lake Beds, van Hees, 1956; Buller, 1958) were deposited in the Lower Elk Point Basin. Distribution of In east-central Alberta, the Earlie Formation is com­ these strata indicate that the approximate southern posed of "interbedded, glauconitic sittstones and fine­ shoreline of this basin was, at that time, formed by the grained sandstones and shales• (Pugh, 1971, p7) and the Deadwood Formation consists of interbedded A A' - 8·5· 47· 4W3M Kii 154' ' K8 1624' Kl Zl51' 1(8 1929' Kii 1&74 ' h, l ' . ! ' §: >. ' H t_ -~':c-~-- ~ ;c t ~ - > =---=--=-=..-~ - - .;:---·- .. h -,.. ~~ '"'-;, ~ 0l ·---? - ~~ \ ~ J ~~ -i ~-: l. - 0 [_ ~ } ! j \ { .:; .i:. r.-l-..... _ _ f - §i ~~ 5- {_A - • o -\ <"" ~ - - ~~ ~ - "';- - - -? <,,_~ 'j --,---~ ~ I =- ~~- Figure 2 - Cross S6Ction showing progressiw truncation of Lower Paleozoic carbonates from south to north. North of the Meadow Lake Escarpment, which formed at th6 erosional edge of the Rad River Formation, Middle Devonian strata (Meadow Lake Fm., Fuzesy, 1980; Meadow Lake &Ids and Ashem Formation, van HHs, 1958) infill the erosional low on th6 Dead· wood/ Earlie Formations. Location of the cross s6Ction Is shown in Figure 1. Logs used are gamma (G) and neutron (N) or sonic (S). Datum Is the top of the Ashem Formation .. 126 Summary of Investigations 1989 Table 1 - Well data. Wei/ location, kelly bushing elevation, and depth of tops of the Ashem Formation, Meadow Lake &<is, Upper Interlake unit, Lower Interlake unit, Stonewall Formation, Stony Mountain Formation, Red River Formation, Winnipeg Forma· tion, Dead'NOOd/ Earlie Formations, and Precambrian in metres. A dash indicates that a unit is not present; a blank space indi- cates no data are available because well is not deep enough. ASH MLB U.INT l. INT STW STM RR WPG DW PC WEL~ ~Q£!TIQN IC. 8. TOP TOP T~ T~ TOP !OP TOP TOP T~ TOP 02·05·61 · 24112 524.6 235.6 244.4 275.2 311.5 319. 4 537.4 08·15·64· 24112 504.7 158.5 170. 7 204.2 384 . 7 07·26·51·25112 479.5 522.4 529. 1 541 .0 568. 1 582. 2 609.6 654.7 671.8 882. 7 16·07·55-25112 521 .8 432.5 437.4 463 .6 478.5 509.3 549.9 555.3 793.4 03·04·59·25112 507. 2 288 . 6 296.6 309.1 339.5 380.1 386.8 05·22·62·26112 589.5 268.8 273. 1 294.4 330.4 374.3 556.0 04·15·56·27112 558.1 442 .6 451.7 459.3 476 .4 506.3 544.4 552.6 810.2 03·18-63-01113 648.3 3n.2 378.0 433.1 640.4 16·26·47·02113 503.5 730.3 741.6 13·19·51·02113 509.6 591 .9 598.0 600.5 630.3 650.1 675 .7 714.1 718.7 1007.1 08· 15·52·02113 539. 8 585.2 591.6 597.4 622.7 637.6 667.2 705 . 9 709.9 990.0 08·08·64-02113 635.8 474 .6 491.6 sn.6 610.5 08·05-47-04113 510. 2 794.3 806.5 824 .5 849.8 865. 0 896. 1 938.5 940.3 08-03-48-05113 512.7 762.9 no.2 789.7 810.8 827. 2 856.8 14 ·31-53-05113 512.1 549.6 556.9 570.0 585 .2 612.6 646.8 648.3 01·36-63-05113 557.8 459 .3 468.8 548.0 581.9 05 · 10-55-0M 498 .7 508.4 518.8 535.8 563.3 595.9 597.4 12·35·58·0M 505.7 382.2 388.0 415.4 444.4 445 .9 09·21-63-08W3 524.9 492.6 503.8 589.5 620.3 07·05-51-09"3 642 .2 826.6 834.2 846. 7 865 .9 898.6 931.5 933.3 02·01·58·09113 490 . 1 420.6 429.2 453.2 485.9 489.2 842.8 04 ·31 ·55·10W3 596.5 628. 5 637.6 646.8 672.4 702 .6 705 .6 02 -16-60·10W3 485.2 383.1 392.0 414.8 416.4 m .1 16·21-61 - 10\ll 499.0 427.3 438 .0 467.0 13-18-65-11113 491.0 495.3 507.8 594.4 615.1 13 · 25 · 51-12113 591 .6 m .8 788.8 06·14· 58-12113 549.2 534.3 548.0 570 .3 571.8 02· 02-60-12113 505 . 1 468.8 481 .6 486.2 10· 20-61-12113 467.3 511.5 523.6 583.4 14· 34 -47- 13113 729.7 1056.7 1065.6 10·16·56·14113 586.4 671.5 687.6 693.1 719.3 n1.2 06-23-58-14113 548.0 554.1 564.8 596.2 05·25·57·15113 565.1 608.1 620 .3 01-16-60-15113 482.5 605.6 620.3 671 .5 13·21·61·15113 470.3 597.4 610.5 688.8 839.