High-resolution ammonite-based biostratigraphy of the Janusfjellet Subgroup (Middle Jurassic – Lower Cretaceous) MIKHAIL ROGOV, Geological Institute of RAS, Moscow of Spitsbergen Key Jurassic sections of Spitsbergen [email protected] Spitsbergen is a key region for reconstructing Middle Ammonite zonal succession of the Middle Jurassic - Jurassic – Early Cretaceous geological history of the Lower Cretaceous of Spitsbergen Barents Sea region, an important pathway of faunal Ammonite Zones immigration and thus crucial area for high-resolution AGE Simplified rock Stage Northwest biostratigraphic correlation within the Panboreal (Ma) Tethyan Europe Spitsbergen succession, Spitsbergen Superrealm. However, precise age of members and 125 125.0±1.0 P. waagenoides P. bidentatum formations of the Adventdalen Group remains Sim. stolleyi C. sarasini Ancy. innexum / controversial, as well as age of the regionally traced gaps or Bogeman I. giraudi pingue Tundra Janusfjellet unconformities, which correlatives are traced across the DH 2,4 U Cape Festningen Hemi. feraudianus Paracrioceras Myclegardfjellet denckmanni Non-marine Barents Sea shelf. Grumant-1 Hemi. sartousi Barremian deposits Gronfjorden Gronfjorden Lundstromdalen A. vandenheckii Para. elegans Grain size Van Keulen fjorden Coron. darsi H. fissicostatum Adventdalen Group in Spitsbergen is overlying the K. compressissima increasing Nick. pulchella Brentskardhaugen Bed, which is containing reworked L Hoplocrioceras Glendonites Kotetish. nicklesi rarocinctum Tavera. hugii auct. fossils of the Toarcian and Aalenian age (Ershova, Repin, 130 Haketangen 1,2 130.0±1.5 S. variabilis 1983; Backström, Nagy, 1985). Pseudothurman. ? ohmi S. marginatus Sorkappland U

B. balearis S. gottschei Pleisiospitidiscus ligatus M. speetonensis M. speetonensis 41 Hauterivian Subsaynella Borehole sections sayni S. inversum S. versicolor 40 Lyticoceras odosoplicatum Key outcrops L E. regale 135 Crioceratites possible loryi E. noricum gap Milanowskia sp., Acanthodiscus Myclegardfjellet [41] radiatus E. amblygonium Speetoniceras ex gr. 136.4±2.0 inversum, , Janusfjellet [40] Euryptychit Criosarasinella paucinodum Pr. bojarkensis 39 furcillata es sp., Neocomites tuberculata Festningen U peregrinus Dichotomites 38 [35] Saynoceras Dicho. ivanovi bidichotomus Valanginian verrucosum through Para. robustum Prohomolsomites cf. Busnardoites P. michalskii 37 petchorensis, Festningen campylotoxus (13 zones) Polyptychites sp., L A. astieriptychus 36 (Frebold,1929) [39] 140 Th. pertransiens P. quadrifidus 35 Selmaneset [36] Tollia tolli, Janusfjellet i 140.2±3.0 r (Wierzbowski et al.,

Th. otopeta e Peregr. albidum Tollia tolli i 34 Dichotomites sp. (Ershova, Bojarkia sp., Janusfjellet s Sur. stenomphalus 2011)[34] s B. mesezhnikowi Th.alpillensis i 33 1983) [38] (Wierzbowski et al., o Surites icenii b S. analogus 32

U Berr. picteti . 2011)[33] h t

Malbo. para- b Hectoro. kochi H. kochi 31 u

mimounum S

Dal. dalmasi a c i

privasensis n Runctonia Chetaites a t Berriasian i runctoni 30 Surites cf. analogus, S. c sibiricus c Borealites cf. subalpina o Janusfjellet (Wierzbowski

i suprasubditus, Shulginites sp., b Subcraspedites Chetaites sibiricus, et al., 2011)[32] Craspedites (Taimyroceras) spp. Berriasella o Sub. lamplughi V. lamplughi/ c Janusfjellet [31] Janusfjellet (Wierzbowski Myclegardfjellet [28]

a lamplughi 29 Dh2 (Koevoets et Bgrearnr.dgisrandisj Chetaites chetae . et al., 2011)[29] r r Subcraspedites al., 2018) [30] Craspedites (C.) praeokensis, e Subcraspedites 145 BeBrre. jrar.cojabci obi B preplicomphalus C. (T.) taimyrensis 28 Myclegardfjellet [27] preplicomphalus C. (C.) okensis 27 Pr. andreai Sub. primitivus Praec. exoticus 26 Laugeites U Para. oppressus parvus, Micracanthoceras T. anguiformis Laug. groenlandicus 25 Festningen microcanthum Ga. kerberus Praechetaites exoticus, Crend.anguinus 24 [25] Dorsoplanites sachsi, M.ponti / Burck. Ga. okusensis Festningen [26] Crendonites sp., Myclegardfjellet [23] Suboxydiscites Simoceras Gl. glaucolithus Dors. maximus 23 Festningen [24] taimyrensis, Pro. albani admirandum / Sorkappland [19] Volgian/ biruncinatum Virgatopav. fittoni Dors. ilovaiskii 22 Dorsoplanites Prorasenia sp., M Richterella Pav. rotunda Pavlovia rugosa 21 Paravirgatites sp., spp., Festningen [16] Tithonian richteri P. pallasioides Janusfjellet [20] Festningen S.semiforme P. pectinatus Paravirgatites sp. 20 [22] P. hudlestoni S. darwini L P. wheatleyensis Euprionoceras 150 P scitulus possible Hybonoticeras . sokolovi, hybonotum P. elegans gap Pavlovia cf. rugosa, Myclegardfjellet [21] Festningen [17] 150.8±4.0 Aulacostephanus Sub. taimyrensis Hybonoticeras autissiodorensis 19 Hoplocardioceras beckeri Aulacostephanus Hopl. decipiens decipiens, Agard Bay [18] 18 Amoeboceras freboldi, Van eudoxus Amoeboceras klimovae, Amoebites bayi, Euprion. sokolovi Keulen Fjord (Ershova, Aula. eudoxus 17 Cape Muri (Ershova, 1983) Van Keulen 1983) [14] Asp . acanthicum Aulacostephanoides [15] Fjord (Ershova, Amoeboceras rosenkrantzi, Kimmeridgian Crussol. divisum mutabilis Zenostephanus 1983) [16] Sorkappland (Ershova, Ataxioceras Amoeboceras ex gr. sachsi [16] 1983) [14] hypselocyclum Amoebites 16 regulare, Oppdalen Tethyan Sutneria platynota Rasenia kitchini Prionodoceras ex gr. serratum, 154.55±4.0 cymodoce (Ershova, 1983) [13] Subnebrodites Grumant 1 borehole (Ershova, 155 planula Amoeboceras ex gr. ilovaiskii, 1983) [12] Pictonia baylei Plasm. bauhini 15 155.65±4.0 Festniongen [11] Boreal Epipeltoceras Ringsteadia A. rosenkrantzi 14 bimammatum pseudocordata A. regulare 13 Maltoniceras U Subvertebriceras sp., Per. cautisnigrae A. serratum 12 bodeni, Van Per. bifurcatus Van Keulen Fjord Plasmatoceras sp., Keulen Fjord A. ilovaiskii 11 (Ershova, 1983) [9] Sorkappland [9] (Ershova, Gregoryceras Perisphinctes pumilus 1983) [10] Transversarium M. tenuiserratum 10 Cardioceras spp., Bogeman Cardioceras Oxfordian M Tundra and Sorkappland Subvertebriceras percaelatum, Van Keulen 9 (Ershova, 1983) [8] Fjord (Ershova, 1983) [8] Perisphinctes (A.) plicatilis denseplicatum Longaeviceras spp. [M and m], Bogeman Cardioceras 160 Cardioceras cordatum 8 Tundra and Lundstromdalen (Ershova, L cordatum 1983) [6] Quenstedtoceras (Q.) mariae S. obliteratum? 7 Scarburgiceras sp., DH2 161.2±4.0 borehole (Koevoets et al., Quenstedtoceras (L.) lamberti Longaeviceras 2018) [7] U keyserlingi 6 Dolganites pomeroyense, Wimanfjellet (Kopik, Pelto. athleta Pelto. athleta D. pomeroyense? Wierzbowskji, 1988) [5] Ery. coronatum Ery. coronatum 5 Callovian M Rein. anceps Kosmo. jason Macrocephalites Sig. calloviense possible Dolikephalites) Proplanulites gap L gracilis koenigi Bull. bullatus Macro. herveyi Subvertebriceras Cadoceras calyx, Janusfjelet [4] aff. zenaidae, 164.7±4.0 Clydoniceras (C.) discus 165 Cadoceras calyx 4 Sorkappland Hecticoceras (P.) Oxycerites orbis U retrocostatum Cado. variabile 3 (Ershova, 1983) Pro. hodsoni Cado. bremeri Ar.cranocephaloide 2 [10] Bathonian M. morrisi / T. subcontractus Cadoceras barnstoni, Hornsunn Procerites (P.) progracilis Arcticoceras (Ershova, Korchinskaya 1980 L ischmae 1 Pro. aurigerus A. tenuiplicatus unpubl.rep.) [3] Zigzagiceras zigzag 167.7±3.5 Parkinsonia (P.) parkinsoni U Garantiana garantiana Strenoceras niortense Arcticoceras cranocephaloide and Kepplerites sp., Sorkappland [2] Bajocian Stephan. humphriesianum 170 Kepplerites svalbardensis, Sassenfjorden and Janusfjellet [4] propinquans (= zone E. (O.) sauzei) L Key ammonites Witchellia laeviuscula Re-deposited Hyperlioceras discites fossils Arcticoceras ishmae, Sorkappland and 171.6±3.0 Festningen (Ershova, 1983) [1] U Graphoceras concavum Brasilia Basal part of the Adventdalen Group is characterized by ammonite genus Arcticoceras, indicating Lower Bathonian Ischmae Aalenian Ludwidgia bradfordensis M Ludwidgia and Middle Bathonian Cranocephaloide ammonite zones (Mitta et al., 2014). A prominent assemblage with Kepplerites Aalenian M murchisonae Ludwidgia murchisonae svalbardensis and cardioceratids above Arcticoceras-bearing unit is typical for the Upper Bathonian Variabile and Calyx Zones. Typical Lower Callovian ammonites are unknown in Spitsbergen. Middle Callovian is mainly represented by its uppermost part 175 L Leioceras opalinum (cf. Kopik, Wierzbowski, 1988), while ammonites typical for lower part of the Middle Callovian remain unfigured (Ershova, 175.6±2.0 Korchinskaya, 1980). Upper Callovian here is well-characterized by numerous records of cardioceratids. Although presence of Middle-Upper Oxfordian gap is widely accepted by those who studying Jurassic of Spitsbergen and adjacent areas, in fact nearly full succession of the Oxfordian ammonite zones was established for this region by Ershova (1983). In the famous Festningen section basal part of the Late Jurassic black shales (Lardyfjellet Mb) is dated by early Amoeboceras as Glosense (=Ilovaiskii) Zone. Kimmeridgian Stage in Spitsbergen is represented by full succession of Boreal zones (Rogov, 2014), and only two thin intervals are characterized by short-term appearance of Subboreal aulacostephanid ammonites (cymodoce and sachsi horizons), possibly indicating small-ranged climate oscillations.The Volgian Stage in Spitsbergen is intensively studied during the last decades. Now nearly full succession of the Middle and Upper Volgian zones is established here (Rogov, 2010; Wierzbowski et al., 2011), while completeness of the Lower Volgian still questioned, because only its uppermost part is characterized by ammonites. It is very possible, that lower part of the Lower Volgian is absent here, as in the many other Arctic sites, being removed during the Middle Volgian transgression. Ryazanian and Valanginian Stages, well-characterized by ammonites and buchiid bivalves, seems to be nearly complete in Spitsbergen (Frebold, 1929; Ershova, 1983; Wierzbowski et al., 2011). The same is true for glendonite-bearing Upper Hauterivian deposits, which are characterized by Speetoniceras and Simbirskites. However, presence of the Lower Hauterivian in Spitsbergen still not confirmed by ammonite records. Key references Ershova E.S. (1983) Explanatory notes for the biostratigraphical scheme of the Jurassic and Lower Cretaceous deposits of Spitzbergen archipelago. Leningrad: PGO Sevmorgeologia. 88 p., 1 fig., 18 tab., 50 pls. [in Russian]. Frebold H. (1929) Ammoniten aus dem Valanginien von Spitsbergen // Skrifter om Svalbard og Ishavet. Nr.21. 24 S. Koevoets M.J., Hammer Ø., Olaussen S., Senger K., Smelror M. (2018) Integrating subsurface and outcrop data of the Middle Jurassic to Lower Cretaceous Agardhfjellet Formation in central Spitsbergen // Norwegian Journal of Geology, V. 98, P.1–34. Rogov M. A. (2010) New data on ammonites and stratigraphy of the Volgian Stage in Spitzbergen // Stratigraphy and Geological Correlation, Vol. 18, No. 5, P.505–531. Rogov M.A. (2014) An infrazonal ammonite biostratigraphy for the Kimmeridgian of Spitsbergen // Norwegian Petroleum Directorate Bulletin, Vol. 11, P.153–165. Wierzbowski A., Hryniewicz K., Hammer Ø., Nakrem H.A., Little C.T.S. (2011) Ammonites from hydrocarbon seep carbonate bodies from the uppermost Jurassic – lowermost Cretaceous of Spitsbergen and their biostratigraphical importance // N. Jb. Geol. Paläont. Abh., 262. P.267–288. http://jurassic.ru/rogov.htm