The Spearfish Formation in the Williston Basin of Western North
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University of North Dakota UND Scholarly Commons Theses and Dissertations Theses, Dissertations, and Senior Projects 1964 The pS earfish Formation in the Williston Basin of western North Dakota Wallace G. Dow University of North Dakota Follow this and additional works at: https://commons.und.edu/theses Part of the Geology Commons Recommended Citation Dow, Wallace G., "The peS arfish Formation in the Williston Basin of western North Dakota" (1964). Theses and Dissertations. 75. https://commons.und.edu/theses/75 This Thesis is brought to you for free and open access by the Theses, Dissertations, and Senior Projects at UND Scholarly Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of UND Scholarly Commons. For more information, please contact [email protected]. "11IB S:.2.ARFISH FO::C1ATI0N IN THE WILLISTON BASI~ OF W2STli2.. N NORTH DAKOTA by Wallace G. Dow,, B.A. in Geology, Rutgers University, New Bruns1dck, 1959 A Thesis Submitted to the Faculty of the Graduate School of the University of North Dakota in partial fulfillment of the requirements for the Degree of Master of Science Grand Forks, North Dakota Hay 1964 'E:iis thesis suhTd.ttcd by Wallace G. Dow in partia.l f"J.lfill:11ent of the requireraents for the Degree of Master of Science in the University of North Dakota, is he~by approved by the Co1nrrdttee under whom the w"Ork has been done. Chairman 7 Dean of the G'aduate School 313791- CONT .•::J\!TS Introduction. l General. • . • . 1 Nethods of Study . • • . 4 Acknowledgments. • . • • . • . 6 Stratigraphy. • . • . 7 Units underlying the Si)ear.fish Formation . 7 Spearfish Formation. .. 8 General . • . 3 Belfield }!ember • . • . 10 u· .ine Salt iYiember. • . 13 Saude Iviember. • • . • . ....ul t:. Units overlying the S1jearfish Formation • . 21 Stratigraphic Relationships and Correlations. 2J Structaral fil.ements ~? . • • . /..., General. • . • . 32 Hesson Anticlin~ . • • . • . 0 . 32 Cedar · C1--eek Anticlin.e '))' . • . • • . ...rt Bov..1l1lan Low . • . 36 Golden Valley Low. • . 37 Stark High . • . • . ·37 Mercer High. • . • . '=I?...,., i iccnomic Geology •. 39 Kno1m Oil Fields . • . 39 1=>e troleu..'il pos.sibilities. • . 39 Salt . • . • . 40 Ground :•later and Gypsmn. 41 Summary . • . • • . 42 Bibliography. • . Lr,3 ii LIS·:::' OF ILLUS'I.'.rLi\TIO:{S 1 UpiJer part of .the Spearfish Formation and Gyps·.. ~.:.'n "") Spring Formation near Four Corners, Wyoming. • .) 2 U?per part of the Spearfish Fornia tion, G;y:Jst1.It1 Spring For:nation and Sundance Formation near Devil 1 s Tower, "j l{yoming •• • • ..I 3 Ind.ex map show"ine li.-rn.i ts of, the Spearfish Formation in the \·iilliston Basin and adjoining areas. • • • . .5 4 Typical radiation and electric logs of the Spearfish Formation and the Poe Member of the Piper Formation. 9 5 1ype log of the Belfield Member. 11 / 1 :::: 0 'i'ype log of the Pine Member. • . -..) 7 Type log of the Saude Member . • 18 8 ?2."eviou.s and present nomenclature of the post Mi.nnekahta, Pre-Piper rocks of the Williston 3asin. • 24 9 Cross section sho-;,ung correlation of the G marker bed with the top of the Goose Egg For-.m.ation. • • • • • • 27 10 Chart showing correlation of the Spearfish Formation i"'-ri th laterally equivalent rocks in Canada, South Dakota, and -~-f.rorning. • • 31 11 ~ocation map showing structures that affected ,.. ...... Spearfish sedimentation. .)J 12 Isopachous map of the Dun.~am beds showing solution cha.:i."Jnels in the Charlson Field, McKenzie County, North Dakota. • . iii ?lates (in pocket) l Location Nap ·,;.._,· ~ ..... 2 Isopachous Hap of the Du:L~~"Tl beds 3 Isopachous Hap of the Spearfish Format.ion 4 Isopachous Hap of the Saude Hember 5 Isopachous Yiap of the G marker bed / 0 Isopachous lv'iap of the Pine Member 7 Isopachous Map of the Balfield Member 8 P-.ce-Spearfish Subcrop Map 9 Southern Half" of the North-South Cross Section in rforth Dakota 10 Northern Half of the North-South Cross Section in North Dakota ll Northern East-Uest Cross Section in North Dakota 12 Southern 3ast-:1est Cross Section in North Dakota 13 Fence Diagram of the Spearfish Formation 14 Index I.vlap of Blaf.:k Hills-North Dakota Sections 15 :Saste1"n :alack Hills-North Dakota Cross Section 16 -~{estern Black Hills-No~th Dakota Cross Section 17 Cross Section Showing Dur..ham Salt Solution iv - TH~ SPB!aFISH FORHATION IN TIE WILLISTON BASIN OF ~iESTERN NORTH D}Jm·rA Wallace G. Dow Il'!TRODUCTION General ·The Spearfish Formation was named by Darton (1899, p. 387) ~rl10 later described it (1901, p. 516) as a conspicuous series of gypsiferous red beds croppi~g out in the vici..l'lity of the Black F.ills, South Dakota. The ·Spearfish Formation, as originally defined, included all rocks between the Minnekahta L:L."llestone of Per:alian age and the Sur.da.~ce Formation of Jurassic age. In the absence of fossil evidence, Darton (1901, p. 519) tentatively assigned a Triassic age to the Spearfish although he believed the lower portion may be Per:r..i.an in age. More recently, a unit of gypsum interbedded with maroon and gray shales originally included at the top of Darton's Spearfish have been redesignated as the Gypsum _Spring Formation of Yliddle Jurassic age (I!rJ.ay, 1947, p. 237). Maple and Bergenda...111 (1956. p. 84) supported this correlation and placed an unccnfonr.ity, representing 1 -·C 2 most o:f Lower Jurassic time, bet1.-1een the Spearfish and tho Gusur1 Spring Formations. The Spearfish Formation of the Black F...::..113, as restricted, contains red beds a::1d ~JPSU..1i'lS of Permian a::id Tria3sic age. The Spearrish Formation crops out in a red valley of variable .i..• ~i.dth that encircles the Black Hills. It also crops out.along i.,,i.16 Belle Fourche aiver in the vicinity of Devil's Tower, Wyoming (Plate 14). Thicknesses of the formation in the Black riills vary frcm 400 to 700 feet. Darton (1909, p; 28-JO) gave several measured sections cf the lh"rlited exposures present. Figure l shows the upper part of the Spearfish Formation on the west flan..~ of the Black Hills near Four Corners, Weston County, Wyoming. In this area, the Spearfish is capped by 30 feet of white gypsu.~ of the Gypsur.1 Spring Formation. In the vicir.:.ity of Devil's Tower, Crook County, Wyoming, the Gypsu.111 Spring Formation is ctly about 10 feet thick. Detail of the upper part of the Spea_j,_~fish in this area is provided by Rea and Paape (1958, p. 305). Tl"us section, show:tJ. L""l figure 2, consists in general of a predomina11.ce of or~ge- red siltstone with maroon shale and fine sandstone interbeds. The discovery of oil in the Williston Ba.sin of No1"'th Da..'t{ota in 1951 spurred an extensive drilling progra.:.'il which revealed a ser·ies of red siltstones and shales with thick salt interbeds in the S'i1bsurf2.ce of weste~n North Dakota ar~d eastern Montana. The stratigraphic position of these beds suggested that they might be equivalent to the Spearfish Formation of the Black Hills. Poor well control between the ce~tral part of the basin and the outcrop sections, however, precluded defi~i~a correlation i-ti. th the type Spearfish and the term 11 Spear.fish II was us8c. -- ··-------~----~-----.......----------~---------------.,.---~------,--~ 3 Figl_!re I - Upper part of the Spearfish Formation capped by 30 feet of Gypsum Spring Formation. Red Butte. 5 miles south of Four Corners, Weston County. Wyoming. Figure 2 - Upper part of the Spearfish Formation, the Gypsum Spring Formation, and the Stockade Beaver Member of the Sundance Formation. East side of Devil's Tower, Crook County. Wyoming. wi.th some reservation. Subsequently nu:nerous and varied correlat::.ons appeared, all of which were based on lL"'Ilited well control. Due to a considerable eA1)ansion of available data in recent yeaxs, a new lo_ok at these strata seemed justi:fied. The main purpose o:f this study is to produce a detailed discussion of these rocks in the western part of North Dakota and to establish, if possible, a cor- relation with the type Spearfish north of the Black Hills. Methods of Study The combined use of mechanical and sa:nple logs provided the data on which this report is based. lv!echanical logs of 288 wells in western North Dakota were chosen so as to provide the best coverage possible. In areas ·where wells are closely spaced, approxi.mately one well per township was used while in other areas, a 11 available well control was em.ployed. ·Detailed mapping of the Spearf'ish Forrr.:1tion was restricted to North Dakota we~t of 101° longitude (Figur·e .3). L--i addition, two cros·s sections were prepared to trace the Spec:r::isn Jo~mation from the subsurface of the Williston Basin to a bore nole six miles north of the outcrop area near the South Dakota - Wyoming border. Plates 1 and 14 show the well control used in the preparation o:? this report. Gamma ray a..-rid lateroresistivity curves we:::-e used whenever possible because they a.r~ the most abundant and provide the best definition of the strata involved. Tops were taken fron1 go.mm.a ray logs., ·when they ·were available, to provide U:"'.ii'o:-m.ity in correlatior:.. Hicrolatero, section gage, ~d neutron curves proved use~ul in I I \ .... \ SCALE O 50 100 M(LES I ==-==~:== l Figure 3 - Index map showing approximate iimits of the Spearfish Formation end equivdents in the Willisb"1 Basin. Modified slightly after Ziegler.