Chapter 6 Subsurface Stratigraphic Cross Sections Showing .

Chapter 6Subsurface Stratigraphic Cross SectionsShowing Correlation of Cretaceous andLower Tertiary Rocks in the Bighorn Basin,Wyoming and MontanaBy Thomas M. FinnChapter 6 ofPetroleum Systems and Geologic Assessment of Oil and Gas in theBighorn Basin Province, Wyoming and MontanaBy U.S. Geological Survey Bighorn Basin Province Assessment TeamU.S. Geological Survey Digital Data Series DDS–69–VU.S. Department of the InteriorU.S. Geological SurveyClick here to return toVolume Title Page

U.S. Department of the InteriorKEN SALAZAR, SecretaryU.S. Geological SurveyMarcia K. McNutt, DirectorU.S. Geological Survey, Reston, Virginia: 2010For more information on the USGS—the Federal source for science about the Earth, its natural and living resources,natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGSFor an overview of USGS information products, including maps, imagery, and publications,visit http://www.usgs.gov/pubprodTo order this and other USGS information products, visit http://store.usgs.govAny use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by theU.S. Government.Although this report is in the public domain, permission must be secured from the individual copyright owners toreproduce any copyrighted materials contained within this report.Suggested citation:Finn, T.M., 2010, Subsurface stratigraphic cross sections showing correlation of Cretaceous and lower Tertiary rocksin the Bighorn Basin, Wyoming and Montana: U.S. Geological Survey Digital Data Series DDS–69–V,14 p.ISBN: 1–4113–2667–5

iiiContentsIntroduction.1Stratigraphy.6Lower Cretaceous Rocks.6Cloverly Formation.6Thermopolis Shale.6Muddy Sandstone.6Upper Cretaceous Rocks.6Mowry Shale.6Frontier Formation.8Cody Shale.8Mesaverde Formation.8Meeteetse Formation, and Lewis and Bearpaw Shales.9Lance Formation.9Paleocene Rocks.10Fort Union Formation.10Lower Eocene Rocks.10Willwood and Tatman Formations, 1.2.3.4.5.Map of the Rocky Mountain region showing Laramide basins.2Index map of the Bighorn Basin.3Stratigraphic chart of Cretaceous and lower Tertiary rocks.4Index map of the Bighorn Basin showing the network of cross sections.5Regional stratigraphic cross section of Cretaceousand Paleocene rocks.7Plates1–6. Stratigraphic sections showing correlation of Cretaceous through lower Tertiary rocks.1. Cross section A–A’ along the Nye-Bowler lineament. link2. Cross section B–B’ from the Beartooth Mountain front to theWhistle Creek anticline . link3. Cross section C–C’ from the Heart Mountain gas field to Emblem gas field . link4. Cross section D–D’ from the Oregon Basin anticline to Greybull . link5. Cross section E–E’ from the Grass Creek anticline to the Five Mile trend. link6. Cross section F–F’ from Montana to the southeastern margin of theBighorn BasinSheet 1 of 2. linkSheet 2 of 2. link

Subsurface Stratigraphic Cross Sections ShowingCorrelation of Cretaceous and Lower Tertiary Rocks in theBighorn Basin, Wyoming and MontanaBy Thomas M. FinnIntroductionThe stratigraphic cross sections presented in this reportwere constructed as part of a project conducted by the U.S.Geological Survey (USGS) to characterize and evaluate theundiscovered oil and gas resources of the Bighorn Basin(BHB) in north-central Wyoming and south-central Montana(fig. 1). The primary purpose of the cross sections is to showthe stratigraphic framework and facies relations of Cretaceousand lower Tertiary rocks in this intermontane sedimentaryand structural basin, which formed in the Rocky Mountainforeland during the Laramide orogeny (Late Cretaceousthrough early Eocene time). The BHB is nearly 180 mi long,100 mi wide, and encompasses about 10,400 mi2. The basin isstructurally bounded on the northeast by the Pryor Mountains,on the east by the Bighorn Mountains, and on the south by theOwl Creek Mountains. The northern margin includes a zoneof faulting and folding referred to as the Nye-Bowler lineament (Wilson, 1936). The northwestern and western marginsare formed by the Beartooth Mountains and Absaroka Range,respectively (fig. 2).The cross sections were constructed from boreholegeophysical logs of 62 wells drilled for oil and gas exploration and production. The stratigraphic interval extends fromthe base of the Cretaceous into the lower Eocene (fig. 3).The datum for all sections is the top of the Teapot SandstoneMember of the Mesaverde Formation or equivalent strata. Thisdatum was selected because it is easily identified on most welllogs and is present throughout the basin.In most wells, a gamma-ray or spontaneous-potentiallog was used in combination with a resistivity or conductivitylog to identify and correlate units. The gamma-ray andspontaneous-potential logs are typically used to differentiatebetween sandstone and shale; however, in the Bighorn Basinthe spontaneous-potential response is typically subdued in thesandstone intervals showing little curve deflection. In areasof greater drilling density, logs from wells located betweencontrol wells on the cross sections were used to aid in makingcorrelations. Coal beds were identified from gamma-raylogs in combination with density and (or) sonic logs whereavailable, and are shown as a long, heavy black bar on thedepth track of each log. The heavy black bars representingcoal beds only show the position of the coal bed(s) and are notproportional to true thickness. In addition to the stratigraphicinformation, oil and gas shows, oil- and gas-producingintervals, perforated intervals, and drillstem test intervalsare also shown on the cross sections. This information wascompiled from IHS Energy Group (2008) well data, theWyoming Oil and Gas Conservation Commission Web site(2008), and drilling reports in the USGS well log files.The locations of the six stratigraphic cross sections are asfollows (fig. 4): Section A–A extends for about 26 mi along the NyeBowler lineament (pl. 1). Section B–B extends for 30 mi southeast from theBeartooth Mountain front to the southwest flankof Whistle Creek anticline (fig. 2) on the northeastmargin of the basin (pl. 2). Section C–C extends nearly east-west about 40 mifrom Heart Mountain gas field to Emblem gas field(fig.2) (pl. 3). Section D–D extends from near the southern end ofthe Oregon Basin anticline for about 50 mi to nearthe Greybull oil field (fig. 2) on the eastern margin ofthe basin (pl. 4). Section E–E extends from near the southeast end ofGrass Creek anticline northeast about 40 mi to nearthe southern end of the Five Mile trend (fig.2) (pl. 5). Section F–F extends approximately 130 mi southeast from the Nye-Bowler lineament, through theClark’s Fork sub-basin and along the Five Mile trend to the Sand Creek anticline (fig. 2) near the southeastern margin of the basin (pl. 6, 2 sheets).For sections A–A to F–F (pls. 1–6) the horizontal scaleis about 1 in. 1.25 mi and the vertical scale is about 1 in. 500 ft.

2   Subsurface Stratigraphic Cross Sections Showing Correlation of Cretaceous and Lower Tertiary Rocks, Bighorn Basin108 BullMountainsBasinhornCONMrifttSangre de CristoRio(Neogene)BasinupliftGrandeonRatSan JuanBasintoCrisderengfieldUT COAZ NMuplifTetonupliftbelticorogenSanSw Rafaell elupliftSa100 MILESif tnlupCordillerallsge50HiRant0volcanicNacimiento uplift36 NECOBasinFrontuplifJuanSan JuanupliftWYrupliftatchSawSouth ParkBasinSanThrust orreverse faultDenvewBoceanGunup nisonlift38 kacinedicMeePicsincomup palif hgtreNorth and MiddlePark s nainftPark Range upliBasinpliftSDNEille uShirleyBasinsAxialinBasarcsinGranite Muplif ountainttGreater GreenRiver BasinupliftrpeUintaBadrea MaSierruplift40 uplifNDSDMTWYsCaftRiverlinsRaw ftupliUintasinOwl Creek uplidarchrRiveiftrnndWiWi nverIDWYUTCityuplhoicsBaRi42 esBigPryorMtns.Bigcanvol44 Mil104 de rPowNye-BowlineamlerBeentaaro up rtooka lift thAbsMTID106 intd PoReeynclinesCrazyMountainsBasinBriup dgerlif t46 110 LarBa amisin e112 Figure 1. Map of the Rocky Mountain region extending from southern Montana to northernNew Mexico showing the locations of Laramide sedimentary and structural basins (in brown)and intervening uplifts. Modified from Dickinson and others (1988).

Introduction   3110 F0GreybullF0050Five MileLittleBuffaloBasinWorlandGrass tseDobie 220MILESticanEmblem5n10T55NF0ainFault0Fesnaan ke Mtic olin unetT9SR40EGas fieldMo00FAbsaroka-50RattlOil 8T55Ngh400GreybullBiR95WElk BasinBadgerBasinPhysiographic or structuralfeature mentioned in text7ryo nsPr ntaiouDryCreekPrecambrian rocks-5000WyomingTertiary volcanic rockslineamMBeaMo rtoount thaMontana ins44 107 R35ER25EBighorn Basin ProvinceT5S45 108 109 ET40NMountainR94WsR90WR85WFigure 2. Index map of the Bighorn Basin showing major structural elements, and oil and gas fields that produce fromCretaceous and Tertiary reservoirs. Physiographic features referred to in the text: (1) Grass Creek anticline, (2) OregonBasin, (3) Five Mile trend, (4) Whistle Creek anticline, (5) Oregon Basin fault, (6) Greybull, (7) Sand Creek anticline,and (8) Clark’s Fork sub-basin. Structure contours drawn on top of the Teapot Sandstone Member of the MesaverdeFormation. Contour interval 1,000 ft. Modified from Johnson and Finn (1998), and Ver Ploeg (1985).

4   Subsurface Stratigraphic Cross Sections Showing Correlation of Cretaceous and Lower Tertiary Rocks, Bighorn BasinMontanaSystemEOCENE (part)StageWyomingNorthern Bighorn BasinSouthern Bighorn BasinTatman FormationWasatch FormationPALEOCENETERTIARY (part)SeriesNorthern Bighorn BasinWillwood FormationWillwood FormationFort UnionFormationFort UnionFormationLanceFormationLanceFormationFort UnionFormationMaastrichtian?Hell CreekFormationLennep SandstoneBearpaw ShaleBearpaw ShaleMeeteetseFm.Meeteetse FormationLewis Sh.Lewis Sh.Parkman SandstoneClaggett ShaleEagle SandstoneVirgelle Ss. Mbr.middlepartClaggett Mbr.Lower memberMesaverdeFormation(main part)middlepartClaggett Mbr.LowermemberSantonianTelegraph Creek Fm.Cody Shale"chalk kick""chalk kick""chalk kick"Frontier FormationFrontier FormationFrontier FormationMowry ShaleMowry ShaleMowry ShaleMuddy SandstoneMuddy SandstoneMuddy SandstoneThermopolis ShaleThermopolis ShaleThermopolis anian TuronianAptianAlbian?"rusty beds"Greybull Ss. Mbr.Pryor ConglomerateMbr.Morrison Formation"rusty beds"Greybull Ss. Mbr.Pryor ConglomerateMbr.Morrison FormationCloverlyFormationCody ShaleCloverlyFormationCody ShaleConiacianLOWER CRETACEOUSMesaverdeFormation(main part)Teapot Ss. MemberMesaverde FormationCampanianUPPER CRETACEOUSCRETACEOUSJudith RiverFormationMesaverde FormationTeapot Ss. Member"rusty beds"Greybull Ss. Mbr.Pryor ConglomerateMbr.Morrison FormationFigure 3. Stratigraphic chart of Cretaceous and lower Tertiary rocks in the BighornBasin, Wyoming and Montana. Modified from Keefer and others (1998), and Johnsonand Finn (2004).

Introduction   5110 Nye-BAowlerTertiary volcanic rockslineamentPMesaverde outcropMFouA'T9SWyomingR101WBT57NPrecambrian rocksryo nsPr ntailate 1BeaMo rtoount thaMontana insWell lf 90Wlinain(nicntn ataiunesnaan ke Mtic olin unetT55NMoPlate6Rattl9SnepC40 TR40EMILESSheAbsarokaT55NT50Ne44 107 R35ER25EBighorn Basin ProvinceT5S45 108 109 e 4. Index map of the Bighorn Basin showing the network of cross sections presented in this report.Section A–A’, plate 1; section B–B’, plate 2; section C–C’, plate 3; section D–D’, plate 4; section E–E’, plate 5; andsection F–F’, plate 6.