Durham Research Online Deposited in DRO: 26 January 2017 Version of attached le: Published Version Peer-review status of attached le: Peer-reviewed Citation for published item: Hall, R. and McNicoll, V. and Gr¤ocke, D. R. and Craig, J. and Jonhston, K. (2004) 'Integrated stratigraphy of the lower and middle Fernie Formation in Alberta and British Columbia, western Canada.', Rivista italiana di paleontologia e stratigraa., 110 (1). pp. 61-68. 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Durham University Library, Stockton Road, Durham DH1 3LY, United Kingdom Tel : +44 (0)191 334 3042 | Fax : +44 (0)191 334 2971 https://dro.dur.ac.uk Rivista Italiana di Paleontologia e Stratigrafia volume I l0 no. I pp.61-68 April 2OO4 INTEGRATED STRATIGRAPHY OF THE LO\TER AND MIDDLE FERNIE FORMATION IN ALBERTA AND BRITISH COLUMBIA, \trESTERN CANADA RUSSELL HALL', VICKI MCNICOLL" DARREN GRÒCKE" TAMES CRAIGI& KEVIN TOHNSTON Receiaed Septenber 19, 2002: accepted Septenber 30,2003 Key toords: Jurassic, ammonìtes, biochronology, coccoliths, U-Pb analyses, have recently been obtained from fossilif- U-Pb geochronolory, strontium isotopes, zircons, Fernie Fornration, erous volcano-sedimentary units in the North American Alberta, Bajocian. Cordillera (Pílfy et al. 2000). There, volcanic products Abstact. The lower and nriddle parts of the Fernie Formirtion are interbedded with ammonite-bearing sediments that in central-western Alberta and sourh-eastern British Colurnbia, ranging provide good biochronological constraints. This integra- from Pliensbachian to ?Brthonian (Earlv to MiddleJurassic) in age, and tion of biostratigraphic and geochronologic data has al- consisting mainly of fossiliferous drrk shales and black limestones, con- lowed improved estimates for the numeric age of tain bentonitic clay horizons which have yielded radiometric rges using Jurassic stage boundaries. U-Pb analysis of zircon crystals. Here we report six nes' ases from the lowermost Red Deer Member (188.3 +1.5/-1 Ma); Highrvood Mem- Tectonism and magmatic events associated with ber (ca. 1/3 Ma;rnd 166.6 + 0.2 Ma); and Grey Beds (167.0 + 0.2 Ma, accretion of allochthonous terranes to the wesrern mar- + 165.6 0.3 Ma, and 165.4 + 0.3 Ma). Some of these bentonites.rre rs- gins of ancestral North America, beginning in about sociated with ammonites and coccoliths which provide biosrratigraph- MiddleJurassic time, are reflected in sediments ic constr;rints. Strontium, carbon and oxyten isotopes measured fronr Jurassic belemnite rostra have been compared in two secrions :rnd the resulting deposited farther east in the \lestern Canada Sedimen- curves are comp:rred with those from western Europe. tary Basin where volcanic ash layers are interbedded vrith ammonite-bearing dark shales of the Fernie For- Riassunto. Le parti inferiore e media della Formazione Fernie mation. In this paper s/e report six new U-Pb zircon nell'Alberta centro-occidentale e nella Columbia Britannica sudorien- ages from analysis of zircons in ash layers from cen- tale, la cui età va dal Pliensbachiano al ?Bathoniano (Gìurassico da infe- riore a medio), e che consistono principalmente in shale fossiliferi scuri tral-western Alberta (Bighorn Creek and irs easrern e calcari neri fossiliferi, contengono orrzzonri di argilla bentonitica che tributary) and south-eastern British Columbia (Ford- hanno fornito datazioni radiometriche con I'analisi U-Pb dei cristalli ing River) (Fig. t). di zircone. riportianio sei nuove datazioni dalla parte più bassa del Qui Detailed geochemical analyses on two sections, Mernbro Red Deer (188.3 +1.5/-1 Ma); dal Membro Highwood (ca. l73Ma,e'166.6 + 0.2 Ma) e dai Grey Beds (167.A + 0.2 Ma, 165.6 + 0.3 Bighorn Creek and its nearby easrern tributary have been Ma, e 165.4 + 0.3 Ma). Alcune di queste bentoniti sono associ,te con completed for strontium, oxygen and carbon isotopic ra- ammoniti e coccoliti, che forniscono le delimitazioni biostratigrafiche. tios. Variations in the strontium-isotope curve derived Gli isotopi dello stronzio, del carbonio e dell'ossigeno misurati da rostri from the analysis of belemnite rostra in these secrions di belemniti sono stati confrontati in due sezioni, e le curve risultanti vengono comparare con quelle dell'Europa nordoccidentale. allow for correlation with that previously generated in Europe (Jones et a|.1994a). lJnfortunately, biochronological constraints in Introduction these two sections depend on only intermittent occur- rences of ammonites, which occur as lateral impressions A significant number of new isotopic dates for cali- on bedding pianes; some levels have also yielded cocco- bration of the Jurassic time-scale, based on high precision lith floras. ' Geoloey & Geophysics, University of Calsary, Calgary, Alberta T2N lN4, Canada. E-mail: hellr(r ucalgary.ca 'Geological Survey of Canada, 601 Booth St., Ottawa, Ontario KlA OE8, Canada 'School of Geographl, & Geologl', McMaster University, Hanrilton, Ontario LSS 4K1, Canada 'PO. Box 668, Bragg Creek, Alberta TOL OKO, Canada 62 R. Hdll, \'. ,llcNitoll, D. Griickc,.l . Craig Et K..f olnstott / t4 YA-HA-TINDA 3 /a RANCH s -:r ^f 'tt I | --ì'--- c! me I rès aooo o .ooo 2000 114' 50' '115' 35 - Bighorn Creek and east tributary localities, Alberta. Scalp Creek 1:50 000 topographic mapsheet, 82 O/13E and Barrier Mountain 1:50 000 topographic mapsheet, 82 Ol12 Fording River, British Columbia. Tornado Mountain 1:50 000 topographic mapsheet, 82 Gl15 V-Vancouver C-Calgary l9-J, Torn.rtir itsc-.lslerntri[lut.rrr',AIbcrt;l:(])lìcclDcer]!{crllbcr.gritlrcfercnce0].+.l5+.ScalpCrcckl:50OOOtopogrlphic (.ì)Highl'tXlC]Mctttbcr'gr.itlrcl.ertrlcc0l0j35,llrliclNjtltlllt;l gricl rcfercncc 013.15.1, Sc.rlp Crccli l:50 000 topogr;rphic nr,rpshcet. lìl ()/llFl I (5) Grcv lìcds, srid reference Ol2 352, Scrlp Crc'eli l: 50 O0O topo*r.rphic nr,rpshcct, Sl Oi 1.1F.. Geological Setting Rcrching maxinrunr thicknesses of only about 300 r'ìì. tìre Fcrnie Fornr.rtiorr is,r recessivc unit occurrinq as In the Foothills and Front R:rnse s of the C;rnrdi,rn isolirtcd outcrops irlonq vallev floors, and was intensely Rockv Mountains thc Fernie Fornrirrion represcnrs al- defornred bv Cretlceous o\.er-thrusring :rcconlpanying nlost the entireJur;lssic; its internrrl subdivision into in- Cordiller:rn tectonism. While nrost units rvithin the Fernie f o rn.r,r I nl e m b e rs r t h c i r I i t h o s t r:r t i u rir p l.r v ir n d b i o s t r;'rt i rÌ rrr- Fornri'rtion have been rerìsonably rvell-dated usinrÌ anlmo- phy, rvere sumrnariscd bv Hall (1981). Lou,cr and Mrdclle nite f:runirs, there are n.ranv faunal gaps (Hall 1984). Dat- Jurassic palrts of tl.re Iìernic Fornrirtion consist predonri- ins of upper Middle Jurirssic units (Hiuhrvood Men.rber, nantlv of grev and black sh:rles, l,'ith nrir-ror siltstones, Grev Bcds) is n'rade rrore difficult bv the strong faunal sandstones, conglonrcrates and linrcstones, the sourcc of provir.rcialitv der.eloped iurongsr :rnrnronires from Late detrital sediments bciÍrs on the cnton to the er.rst. Tl.rcsc B,rjocirn to t:rrly Oxfordian times (Callomon 1984). strata represent the voungest pilrts of the pirssivc rn,rrgin sequence, q,hich irccurlulirted on thc western ntirrgin of cratonic North Arrericrr thror,rgl.rout the Paleoz-oic rrncl Earlv Mesozoic. Thc uppernrost p,rrt of the Fernic l"or- Lithostratigraphy and descriptions of sections nlxtion (Pass:rge Be ds; Oxfordi,rn) rccords :1 conrplctc rc- Ilighorn Creek versrrl in basin polirritl., refle cting :rccretionarv rccronics Thc lorvermost Jurrssic scdinrents ;rt this loc.rlin'consist ol;t occurrins f,rrther rvest, r'hich resr-rltcd in dcvclopnrcnt thin (lÌ ur), plrosph:rtic-pcirirle lig iilling cleprcssions on rrn erosi()nirl surf.rcc clcvclopred ovcr l-orvcr Middle (Sulphur Moun- of ir subsidins forclrrnd brrsin u,ith influx of co;lrse clrìs- to Tri:rssic roclis t.rìn Iìrrnrrtion)l frlgnrcrrtccl;rrnnronites inclic.rtc.r [-.rte Sinenruli.rn .rgc tics, and volcanic rrnd igncous dctritus, from ,r \\'estcrlv for this pebblc bcd (Stcll.rre Subzonc, Obrtrsunr Zone). Above an S source - the rising iìncestrtl Rockv Mountrrins (Poulton nr thick coverccl inten,rl, thc Upper Plicnsb;rchi;rrr Rc'cl Deer Mcmber et rl. 199,1). cortsists oi 9 nr of hard. platl Lrl,rck, limestorrc rrnd shrìlc. The overli- Stratigraphy of tbe Fernie Formations 63 Fig.2 - Carbon, oxygen, and stron- Stable lsotopes 879/8651 lNgg 9971 rirrm isotone curves for the Highwood Member of the J, o o13c""rg%o1vpDB1 o18o""rg%o1veoe1 ^a Fernie Formation at Bighorn or Òr s] -1 012 3 -8-7-6-5-4-3-2-1 .ffi rffiTrTEtffit rffiT|frTffiT|.rlFTffiTffi Creek. Placemenr of Stage la{ anòZone boundaries (in col- ts-ra+ umns under "this study") based on variations in iso- tope curves, not ammonites !-ar found in this section. É,ar + + + '3 Éa{ r-r É-a+ ,a{ l-ar ù-ar r-.O< Fai l+i ts-ai t.....'.ru trglrgtqlgr:J n\6".rs"tr-10i23 -8 -7 -6 -5 -4 -3 -2 -1 o.s.s^o' ^Q' 4s' ing Poker Chip Shale, 12 m thick, consists of more fissile and papery, calcareous siltstones with some poorly preserved lateral impressions of thinly laminated, black silty shales, and in its lower parts conlains a rich Late Pliensbachian ammonites (Hall et al.