6. Paleaontology

6.1. Paleozoic and Mesozoic stratigraphy, paleoceanography and paleoclimate

6.2. Open session in Palaeontology, palaeoecology and paleoenvironments

6.1. Paleozoic and Mesozoic stratigraphy, paleoceanography and paleoclimate

                       ORAL PRESENTATIONS                    

At the boundary between the middle Albian hoplitinid and gastroplitinid ammonite provinces: linking the Arctic with northwest Europe with ammonites in North Greenland .

Peter Alsen^1
1The geological survey of Denmark and Greenland (GEUS)
The Albian is characterized by pronounced provincialism, and within the Boreal Realm endemic faunas form defines separate faunal provinces with only limited faunal communication. Palaeobiogeographic subdivision of the Albian in the Boreal Realm includes a Boreal-Atlantic Subrealm, an Arctic Subrealm and a Boreal Pacific Subrealm (Lehmann et al 2015). During the middle Albian the Boreal-Atlantic is characterized by hoplitinids and corresponds to the European or hoplitinid province of Owen (1979, 1996, 2007). Hoplitinids were dispersed widely in the European shelf seas but also towards the north, where impoverished faunas are recorded in Greenland and Svalbard. The ammonite zonation based on the hoplitinids form a standard for the European Province. In the neighbouring Arctic or gastroplitinid province to the north hoplitinids are totally absent and the issue of accurately dating the gastroplitinids of the Arctic from correlation to the hoplitinid zonation has been a long-lasting problem and commonly discussed in the literature. North-East Greenland (Donovan 1957) and Svalbard (Yershova 1983; Nagy 1970), where faunas are reported to overlap, have, however, no localities were hoplitinids and gastroplitinids are found together in assemblages, or at precisely defined levels within a faunal succession. Recently, an ammonite-rich horizon was discovered in an otherwise rather unfossiliferous Albian succession in Kilen, North Greenland. It contains an assemblage with both gastroplitinid representatives of the Arctic Province and hoplitinid representatives of the European Province. The ammonites thus represent a rare and unique occurrence record of a mixed hoplitinid-gastroplitinid assemblage.

References
Donovan, D.T. 1957. The Jurassic and Cretaceous systems in East Greenland. Meddelelser om Grønland 155 (4), 214 pp.

Lehmann, J., Ifrim, C., Bulot, L. & Frau, C. 2015. Paleobiogeography of Early Cretaceous ammonoids. In Klug, et al. (eds.): Ammonoid Palaeobiology: from macroevolution to paleogeography. Topics in Geobiology 44, 229–257.

Nagy, J. 1970. Ammonite faunas and stratigraphy of Lower Cretaceous (Albian) rocks in southern Spitsbergen. Norsk Polarinstitutt Skrifter 152, 58 pp.

Owen, H.G. 1979. Ammonite zonal stratigraphy in the Albian of North Germany and its setting in the hoplitinid faunal province. In Wiedmann (ed.): Aspekte der Kreide Europas. IUGS Series A, 6, Stuttgart, 563–588.

Owen, H.G. 1996. Boreal and Tethyan late Aptian to late Albian ammonite zonation and palaeobiogeography. Mitteilungen aus dem Geologisch-Paläontologischen Institut der Universität Hamburg 77, 461–481.

Owen, H.G. 2007. Albian ammonite biostratigraphy of the Kirchrode II borehole, Hannover, Germany. Cretaceous Research 28, 921–938.

Yershova, Ye.S 1983: Explanatory account of the biostratigraphical scheme of the Jurassic and Lower Cretaceous deposits of the Spitsbergen Archipelago. PGO Sevmorgeologiya, Leningrad 62, 50 pp. [in Russian]

The secret wonders of the middle Danian

Bodil Wesenberg Lauridsen¹, Kasper Blinkenberg¹, Trine Edvardsen¹ and Lars Stemmerik^1
1Natural History Museum, Denmark
The Danian is named after and known for the imposing bryozoan mounds of Stevns Klint and the cold-water coral mounds of Faxe. Less attention has been on the middle Danian chalk localities in the northwestern part of the Danish Basin. Here the chalk is soft, with a low diversity benthic fauna and a relatively high degree of unevenly distributed flint. The fauna composed mostly of irregular echinoids, bryozoans and crinoids. However, a detailed look into the Danian chalk in Dalbyover, northern Jutland, reveals a much more vivid ecosystem. Echinoids (both regular and irregular), bryozoans, brachiopods, bivalves, serpulids, sponges, asterozoans and crinoids were thriving in this relatively deep and nutrient poor setting. The species all show special adaptations to survival in the environment and many are Mesozoic survivors from the Late Cretaceous chalk sea. One of the dominating species, the irregular echinoid Echinocorys sulcatus appears to be crucial for the ecosystem and is a true wonder of the middle Danian.

Triassic biostratigraphy (ammonoids and palynology) and organic δ¹³C-isotope record of the Wandel Sea Basin, North Greenland

Sofie Lindström¹, Peter Alsen¹, Morten Bjerager¹ and Jussi Hovikoski^1
1GEUS
The presence of Triassic sedimentary rocks in North Greenland was first reported from the Danish Peary Land Expedition 1948-49 by Troelsen (1950). The first descriptions of Triassic fossils, mainly ammonoids, were made by Kummel (1953), and later by Peel et al. (1974). During the Triassic the Wandel Sea Basin (WSB) constituted a continuation of basins in the southern part of the Barents Sea to the east, and of the Danmarkshavn Basin offshore Northeast Greenland to the south. The Triassic succession of the WSB was deposited unconformably on Upper Permian sediments and succeeded by Upper Jurassic – Lower Cretaceous deposits (Håkansson et al. 1991). During recent field campaigns (2012–2013) several outcrop sections and a cored drilling were sampled for palynology, macrofossils, and organic δ¹³C-isotope analysis. The integrated ammonoid faunas and spore-pollen biostratigraphy shows that the exposed Triassic succession of the WSB encompasses a near complete Induan (Dienerian) – Norian succession. The ammonoid faunas are correlated with the established zonation for Arctic Canada (Tozer, 1994), and spore-pollen assemblages correlate well with those of Svalbard and the Barents Sea (Vigran et al. 2014). An especially detailed organic δ¹³C-isotope record is registered for the Smithian–Spathian interval, which can be correlated with previously reported records globally (e.g. Galfetti et al., 2007, Grasby et al., 2013).

References
Galfetti, T., Bucher, H., Ovtcharova, M., Schaltegger, U., Brayard, A., Brühwiler, T., Goudemand, N., Weissert H., Hochuli, P.A., Cordey, F. & Goudun, K. 2007: Timing of the Early Triassic carbon cycle perturbations inferred from new U-Pb ages and ammonoid biochronozones. Earth and Planetary Science Letters 258, 593–604.

Grasby, S.E., Beauchamp, B., Embry, A. & Sanei, H. 2013: Recurrent Early Triassic ocean anoxia. Geology 41, 175–178.

Håkansson, E., Heinberg, C. & Stemmerik, L. 1991: Mesozoic and Cenozoic history of the Wandel Sea Basin area, North Greenland. Bulletin Grønlands Geologiske Undersøgelser 160, 153–164.

Kummel, B. 1953: Middle Triassic ammonites from Peary Land. Meddelelser om Grønland 127(1), 21 pp.

Tozer, E.T. 1994: Canadian Triassic ammonoid faunas. Geological Survey of Canada Bulletin 467, 663 pp.  

Troelsen, J.C. 1950: Geology. In Winther, P.C. et al.. A preliminary account of the Danish Peary Land Expedition 1948-49. Arctic 3, 6–8.

Vigran, J.O., Mangerud, G., Mørk, A., Worsley, D. & Hochuli, P.A. 2014: Palynology and geology of the Triassic succession of Svalbard and the Barents Sea. Geological Survey of Norway Special Publication 14, 1–247.

Biostratigraphic correlation of the Cretaceous to Neogene succession of the western and eastern margins of the Labrador – Baffin Seaway.

Henrik Nøhr-Hansen¹, Graham L. Williams² and Robert A. Fensome^2
1Geological Survey of Denmark and Greenland, GEUS, Øster Voldgade 10, Dk-1350 Copenhagen K, Denmark., ²Natural Resources Canada, Geological Survey of Canada (Atlantic) Bedford Institute of Oceanography
New analyses of the palynological assemblages in 13 offshore wells on the Canadian margin and six on the West Greenland Margin, in conjunction with onshore data, have led to a new biostratigraphic framework for the Cretaceous–Cenozoic strata of the Labrador Sea – Davis Strait – Baffin Bay (Labrador–Baffin Seaway) region and the first broad biostratigraphic correlation of the Canadian and Greenland margins. This framework is based on 167 last occurrences and 18 local or regional, peak- or common-occurrence events for dinocysts (which include three new genera and 16 new species), acritarchs (including one new species), miospores (including one new species), fungal spores and massulae of the fresh-water fern Azolla. Our findings delineate several local and regional hiatuses on both sides of the seaway. The palynomorph assemblages show that most Aptian to Albian sediments were deposited in generally non-marine to marginal marine settings, interrupted by a short-lived shallow-marine episode in the Aptian. A marine transgression commenced in the Cenomanian–Turonian and led to the most open-marine, oceanic conditions in the Campanian–Lutetian. Subsequent shallowing probably began in the late Lutetian and continued into the Rupelian, when inner neritic and marginal marine palaeoenvironments predominated. Throughout the rest of the Cenozoic, inner neritic palaeoenvironments alternated with marginal marine conditions on the margins of the Labrador–Baffin Seaway. Our findings broadly reflect the tectonic evolution of the seaway, with rift conditions prevailing from Aptian to Danian times, followed by drift through much of the Paleocene and Eocene, and post-drift from Oligocene to the present.

Biodiversity, climate and time – resolving the scale, tempo and drivers behind the Great Ordovician Biodiversification Event

Christian M. Ø. Rasmussen^1
1Natural History Museum of Denmark
The early Palaeozoic witnessed two significant pulses in biodiversity increase and a catastrophic mass extinction. All are fundamental events and notably the two radiations had a lasting impact on Phanerozoic ecosystems. The early Palaeozoic has traditionally been considered a super-greenhouse period. This interpretation was primarily based on two lines of evidence: modelling scenarios suggesting CO₂ levels 15–20 times PAL, and a general perception of warmer climate due to what was likely a Phanerozoic sea level maximum during the early Late Ordovician. The interpretation of early Palaeozoic climate, however, is currently undergoing a paradigm shift. Increasing evidence is suggesting a cooler climate throughout most of the Ordovician Period, and the short-lived icehouse conditions traditionally linked to the end Ordovician mass extinctions now appear to continue well into the Silurian. In the midst of this paradigm shift lies the Great Ordovician Biodiversification Event (GOBE) – the greatest marine speciation event of the entire Phanerozoic. Thus, this event now seems to have been unfolding against a background of cooler climate instead of a super-greenhouse, but the exact onset of the GOBE is obscured by contradicting biodiversity estimates. The current talk presents ongoing efforts to unravel the speed and causes of the GOBE by combining three approaches: 1) the construction of a new, high-resolution biodiversity estimate for the early Palaeozoic, 2) an astronomically calibrated timescale through the GOBE, and 3) new abiotic climate proxies based on brachiopod ¹⁸O data. Together, these three lines of evidence provides a highly interesting novel perspective on the event.

Stratigraphic context and environmental changes in the Tuxen and Sola Formations (Barremian-Early Aptian, North Sea): new results from high-resolution carbon and oxygen stable isotopes, major and trace elements, sedimentology and calcareous nannofossils

Nicolas Thibault¹, Kresten Anderskouv¹, Emma Sheldon², Jon Ineson², Anastasios Perdiou¹ and Mohammad J. Razmjooei^1
1IGN, University of Copenhagen, ²GEUS
The Barremian to lower Aptian Tuxen and Sola Formations have been investigated in the North Jens-1 well (Danish Central Graben, North Sea) for environmental changes based on a revised calcareous nannofossil biostratigraphy, geochemical analysis of 316 samples (stable isotopes, hand-held XRF element analysis) and quantitative nannofossil abundance counts of 75 samples. Our results delineate the well-established Barremian rise in carbon isotopes as well as the typical excursions across the early Aptian Oceanic Anoxic Event (OAE) 1a characterized by two short and prominent negative excursions right below and at the base of the Fischschiefer laminated black shale horizon, followed by the long-lasting positive carbon isotope excursion of the lower to upper Aptian. Our new results also show significant cyclic changes in the Barremian carbon cycle with a number of new possible negative and positive excursions that could be defined and used for refinement of the stratigraphy of this stage. Oxygen isotopes and calcareous nannofossil assemblages highlight the coupling of significantly warm episodes associated to eutrophic conditions during deposition of the lower Barremian Munk marl and early Aptian Fischschiefer laminated horizons whereas a significant cooling associated to oligotrophy triggered the deposition of nannoconid chalk in the upper Barremian. Major and trace elements suggest rather similar environmental contexts in bottom-waters for the deposition of the Munk marl and Fischschiefer and advocate for these levels but we denote a conflicting sequence stratigraphic context for the Munk Marl in the North Sea and the equivalent Hauptblätterton in the Lower Saxony Basin of North Germany.

The Ordovician conodonts of the west Sørkapp Land (Southern Spitsbergen)

Tatiana Tolmacheva¹, Aleksandr Larionov¹ and Natalia Kosteva^2
1A.P. Karpinsky Russian Geological Research Institute, ²Polar Marine Geosurvey Expedition
The Ordovician in the Sørkapp Land is known since the 50-ies [1], yet it is relatively poorly examined and its faunas are studied insufficiently. The western Sørkapp Land part between the Olsokbreen and Bungebreen was surveyed in 2013. Here the Ordovician (Sørkapp Land Gr – Hornsundtind and Nigerbreen Fms) and presumably Ordovician-Silurian (Arkfjellet Fm) have been found to form an NE-striking tectonostratigraphic antiform. The section is dominated by various limestones that range in color from almost black to light; layers of chert-bearing limestone also present. The antiform’s SE limb contains two psammitic layers as well as layers of schists and conglomerate. The Early Paleozoic rocks are unconformably overlain by the Devonian red sandstones and/or Triassic.

Conodonts imply that the Hornsundtind and Nigerbreen Fms embrace the Floian to the Middle Darriwilian stratigraphic interval. The lower Floian part of the section yelded Wandelia guyi Smith, Paroistodus proteus Lindstrom, Colaptoconus quadraplicatus (Branson et Mehl), Oepikodus sp., Parapanderodus striatus (Graves et Ellison). The conodont assemblages are dominated by Wandelia guyi typical for the East and North Greenland [2]. The Early Darriwilian is confirmed by Multioistodus sp., Drepanoistodus sp., Periodon sp. The youngest Middle-Upper Darriwilian ages of the section are based on findings of Belodina sp., Periodon sp., Panderodus sp., Drepanodus sp., Protopanderodus sp. The conodonts have Laurentian biogeographic affinity, supporting conclusions based on conodonts from Hornsund [3] and Ny Friesland [4].

References
[1] Lehnert O et al. (2013) Z. Dt. Ges. Geowiss. 164(1): 149-172

[2] Major H and Winsnes T (1955) Norsk Polarinstitutt Skrifter 106: 1-47

[3] Smith M (1991) Medd. Greenland, Geosci. 26: 1-81

[4] Szaniawski H (1994) In: XXI Polar Symposium – 60 years of Polish Research of Spitsbergen: Warszawa (Inst. Geophys. Polish Acad. Sci.), 39-44

                       POSTER PRESENTATIONS                    

The Silurian Lau event – testing plant weathering as driver for ocean anoxia and animal extinction

Julius Havsteen¹, Álvaro del Rey¹ and Tais Wittchen Dahl^1
1Natural History Museum of Denmark, University of Copenhagen
The Silurian period witnessed several climatic events expressed as large positive carbon isotopic excursions in the carbonate rock record. One of these – the Ludfordian Lau event – is the greatest isotopic excursion in the Phanerozoic (δ¹³C increases by ~9‰). Marine carbonates exposed on Gotland (Sweden) preserve this record. Here, we present new isotope data obtained from bulk carbonate rocks using Cavity Ring-Down Spectroscopy. Several extinction events are observed in conjunction with the isotope excursions. During the Lau event, marine animals from the pelagic zone to the benthos were affected in less than 200 kyr. We hypothesize that the Lau event reflects an organic carbon burial episode driven by the colonization of vascular plants on land. At this time, the first rooted plants appeared in the fossil record. They could have intensified weathering rates and sourced more of the biolimiting nutrient, phosphorus, into the oceans. This increased marine primary productivity and ultimately organic carbon burial – now recorded in higher δ¹³C values in carbonate sediments. We test this relationship using uranium isotopes in the same samples to constrain the oxygenation state of the Silurian oceans. Uranium’s long oceanic residence time (~400 kyr) and the preferential incorporation of ²³⁸U relative to ²³⁵U into anoxic sediments makes δ²³⁸U a powerful proxy for global marine anoxic sediment burial.

Chemostratigraphy across the Toarcian Oceanic Anoxic Event in the Aubach section of SW Germany

Iben W. Hougaard¹, Jørgen Bojesen-Koefoed², Oluwaseun O. Edward¹, Małgorzata Rizzi¹, Clemens V. Ullmann³ and Christoph Korte^1
1Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark, ²Geological Survey of Denmark and Greenland (GEUS), Denmark, ³Camborne School of Mines and Environment and Sustainability Institute, University of Exeter, Penryn,
Early Jurassic strata, covering the Toarcian Oceanic Anoxic Event (T-OAE), are exposed in the Aubach section, Wutach area, SW Germany. The T-OAE is characterized by significant organic matter burial, numerous geochemical anomalies and one of the most significant negative carbon isotope excursions (CIE) in the Mesozoic (Jenkyns and Clayton, 1997; Küspert, 1982; Röhl et al., 2001). In the present study, we generated new organic and inorganic carbon isotope values as well as element concentrations (Mn, V, Mo), common organic geochemical data and biomarkers of bulk rock samples. The results are currently utilized to determine fluctuation in the carbon cycle, to evaluate bottom water redox conditions during sediment deposition, and to determine variation in the source of organic matter.

The first results show the well-known negative organic carbon isotope excursion from the semicelatum to exaratum Subzones and the organic geochemical characterization allow the preliminary interpretation that the organic matter source changed to a more marine source during the T-OAE. Fluctuation in the anoxia proxies Mo and V are asynchronous suggesting that the restricted conditions occurred in a larger basin and the reduced conditions prevailed throughout most of the falciferum Zone. Sea-level proxies (Rb/Zr, Zr/Al, Si/Al) suggest a sea level rise synchronous with the change to a more marine source of organic matter and the onset of the T-OAE.

References
Jenkyns, H.C., Clayton, C.J., 1997. Lower Jurassic epicontinental carbonates and mudstones from England and Wales: chemostratigraphic signals and the early Toarcian anoxic event. Sedimentology 44, 687-706

Küspert, W., 1982. Environmental changes during oil shale deposition as deduced from stable isotope ratios. Cyclic and Event Stratification pp. 482-501

Röhl, H.-J., Schmid-Röhl, A., Oschmann, W., Frimmel, A., Schwark, L., 2001. Erratum to “The Posidonia Shale (Lower Toarcian) of SW-Germany: an oxygen-depleted ecosystem controlled by sea level and palaeoclimate” [Palaeogeogr., Palaeoclimatol., Palaeocol. 165 (2001) pp. 27-52], Palaeogeography, Palaeoclimatology, Palaeoecology 169 ,  273-299

Seawater temperature change across the Pliensbachian–Toarcian transition – new isotope data from the Aubach section in SW Germany

Christoph Korte¹, Clemens V. Ullmann², Jesper A. Frederiksen¹, Robert Frei¹, Iben W. Hougaard¹ and Małgorzata Rizzi^1
1Department of Geosciences and Natural Resource Management, University of Copenhagen, ²Camborne School of Mines and Environment and Sustainability Institute, University of Exeter
In the Wutach area of SW Germany, biostratigraphically well-defined Late Sinemurian to earliest Aalenian siliciclastic and carbonate sediments are exposed along the Aubach stream (Riegraf, 1980; Riegraf et al., 1984; Schlatter, 1997; Urlichs, 1997). The locality was sampled in high resolution during several field campaigns in the last years, and carbon, oxygen and strontium isotope datasets have been generated from Low-Mg-Calcite fossils (mainly belemnites) which were screened for diagenesis (see Ullmann and Korte, 2015). Known carbon isotope fluctuations for this period (e.g. Korte and Hesselbo, 2011; Peti et al., 2017) are expressed clearly in the Aubach data, including an about 2 ‰ negative excursion across the Sinemurian–Pliensbachian boundary, a positive excursion in the Late Pliensbachian margaritatus Zone, a negative excursion in the spinatum Zone (hawskerense Sz), a negative excursion of across the Pliensbachian–Toarcian boundary and relatively heavy values up to +4 ‰ in the falciferum Zone. The oxygen isotope values show an increase across the Sinemurian–Pliensbachian boundary, reaching heaviest values of ~ +1 ‰ (with periodic fluctuations) in the margaritatus and early spinatum zones (Late Pliensbachian Cool Mode; Korte et al., 2015). The values start to gradually decrease in the higher hawskerense Subzone (with some heavy values in the semicelatum Subzone), lasting till the earliest Toarcian tenuicostatum Zone. The new data indicate that relatively cool temperatures have existed in the Swabo-Franconian Basin at palaeolatitudes below 40° for most of the Pliensbachian, and that the Toarcian warming may have preceded the negative carbon isotope excursion of the T-OAE.

References
Korte, C. & Hesselbo, S.P. 2011: Shallow marine carbon and oxygen isotope and elemental records indicate icehouse–greenhouse cycles during the Early Jurassic. Paleoceanography 26, PA4219.

Korte, C., Hesselbo, S.P., Ullmann, C.V., Dietl, G., Ruhl, M., Schweigert, G. & Thibault, N. 2015: Jurassic climate mode governed by ocean gateway. Nature Communications 6, 10015.

Peti, L., Thibault, N., Clémence, M.-E., Korte, C., Dommergues, J.-L., Bougeault, C., Pellenard, P., Jelby, M.E. & Ullmann, C.V. 2017: Sinemurian–Pliensbachian calcareous nannofossil biostratigraphy and organic carbon isotope stratigraphy in the Paris Basin: Calibration to the ammonite biozonation of NW Europe. Palaeogeo­graphy, Palaeoclimatology, Palaeo­ecology 468, 142–161.

Riegraf, W. 1980: Kartierung im Kristallin und Jura des Truc de Balduc (Departement Lozère, Südfrankreich) unter besonderer Berücksichtigung von Fazies und Fauna des bituminösen Untertoarciums. Unpubl. Dipl. thesis, Univ. Tübingen, 125 pp., 29 Figs, 3 Tab., 3 attachm.

Riegraf, W., Werner, G. & Lörcher, F. 1984: Der Posidonienschiefer — Biostratigraphie, Fauna und Fazies des südwestdeutschen Untertoarciums (Lias ε), 195 pp. Stuttgart: Enke Verlag.

Schlatter, R. 1997: Das Lotharingium und Carixium im Wutachgebiet. In: Bloos, G. et al., (eds): DUGW-Stratigraphische Kommission – Subkommission für Jura-Stratigraphie, Jahrestagung 1997 in Blumberg-Achdorf, Wutachtal (7.5.-10.5.1997), Exkursionsführer, pp. 13–19.

Ullmann, C.V. & Korte, C. 2015: Diagenetic alteration in low-Mg calcite from macrofossils: A review. Geological Quarterly 59 (1), 3–20.

Urlichs, M. 1997: Das Oberpliensbachium und Toarcium im Wutachgebiet. In: Bloos, G. et al., (eds): DUGW-Stratigraphische Kommission – Subkommission für Jura-Stratigraphie, Jahrestagung 1997 in Blumberg-Achdorf, Wutachtal (7.5.-10.5.1997), Exkursionsführer, pp. 20–30.

Orbital forcing of organic matter quality and quantity in a source-rock formation: the case of the Vaca Muerta Formation, Tithonian-Valanginian, Neuquén Basin, Argentina

Johannes Monkenbusch¹, Alain Lejay², Mathieu Martinez³, Heiko Pälike⁴ and François Gelin^2
1Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade, ²TOTAL, CSTJF, Avenue Larribau, 64000 Pau, France., ³Université de Rennes, UMR 6118 Géosciences Rennes, Campus de Beaulieu, 35042 Rennes cedex, France., ⁴MARUM, Centre for Marine Environmental Sciences, Leobener Strasse 8, Universität Bremen, 28359 Breme
The Vaca Muerta Formation from the Neuquén Basin is an important petroleum source-rock formation in Argentina. A cyclostratigraphic study was conducted, based on a set of continuous data from four wells. The Total Organic Content (TOC) was measured using the LIPS method to investigate the control of orbital forcing on the variation of organic matter distribution. Moreover, the integration of the Rock Eval 6 Hydrogen Index (HI) and Oxygen Index (OI) were tested to understand the climatic conditions which favoured the deposition and preservation of organic matter.

Cyclic changes are attributed to astronomical forcing. The main driver of the oxygenation of the basin was the obliquity. HI, OI and TOC correlate with the precession and the eccentricity.

We attribute this link to changes in the sea level due to fluctuations in ice coverage during the late Jurassic – early Cretaceous and suggest that, with falling sea level, the connection between the Neuquén basin and the proto-Pacific got shallower, resulting in stratification of the basin with warm fresh water sealing off the deeper basin. With rising sea level, the connection to the ocean deepened and the stratifications weakened. Nutrients were mainly supplied by continental run-off from the south of the basin due to monsoonal activity during winter, which varied with the precessional cycle. Warm, hypersaline waters were synchronously formed in the south-east of the basin during summer. This led to the formation of a hypersaline lens in the deepest part of the basin and thus cutting it off from oxygen supply.

The giant Lower Triassic sponge-microbial build-ups from Neotethys

Sylvain Richoz¹, Evelyn Friesenbichler², Aymon Baud³, Leopold Krystyn⁴, Katrin Heindel⁵, Lilit Sahakyan⁶, Jörn Peckmann⁷ and Joachim Reitner^8
1Department of Geology, Lund University, Sölvegatan 12, Se-223 62, Sweden, ²Paleontological Institute and Museum, University of Zurich, Karl-Schmid-Strasse 4, 8006 Zurich, Swit, ³BCG, Parc de la Rouvraie 28, CH-1080 Lausanne, Switzerland, ⁴Department for Paleontology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria, ⁵GeoZentrum Nordbayern, Fachgruppe Paläoumwelt, University of Erlangen-Nürnberg, Loewenichstraße 28,, ⁶Institute of Geological Sciences, National Academy of Sciences of Armenia, 24a Baghramian Avenue, 37, ⁷Institute for Geology, Universität Hamburg, Bundesstraße 55, 20146 Hamburg, Germany, ⁸Department of Geobiology, Centre of Geosciences, University of Göttingen, Goldschmidtstraße 3, 37077
After the end-Permian mass extinction the upper Paleozoic skeletal carbonate factory was abruptly replaced by a non-skeletal carbonate factory and Permian-Triassic boundary microbialites (PTBMs) were flourishing. These PTBMs were abundant in low-latitude shallow-marine carbonate shelves in central Tethyan continents and present during at least four events in the Lower Triassic.

The investigated PTBMs from three different sites in southern Armenia were formed in a distal open marine setting on a pelagic carbonate ramp. They grew during two microbial growth phases in Griesbachian times, whereas the microbialites from the first microbial growth phase co-occur with calcium carbonate crystal fans (CCFs). The microbes formed predominantly thrombolites that vary in size between 5 cm to 1.5 m. The biggest thrombolite has a cone-shaped build-up geometry and an asymmetrical growth, which indicates the influence of a steady bottom current. It consists of numerous thrombolite domes with a top head diameter of up to 8 m width and a total height of up to 12 m. The microbialites are surrounded by a bioclastic wackestone that mainly contains ostracods, foraminifers, microgastropods, thin-shelled bivalves.

Carbon isotope studies were performed on both the microbialites and the surrounding sediment. A comparison between the δ¹³C_sediment and δ¹³C_microbialite revealed that there is little difference (<0.4‰) between these values in the microbialites that formed during the second microbial growth phase. In contrast, the microbialites and CCFs from the first microbial growth phase show differences in the δ¹³C values of up to 2.3‰, which could be due to microbial activity.

6.2. Open session in Palaeontology, palaeoecology and paleoenvironments

                       ORAL PRESENTATIONS                    

Pushing research boundaries: Benefits of temperature ramped gas chromatography in EA-IRMS

Christopher Brodie¹, Oliver Kracht, Andreas Hilkert and Søren Dalby
¹Dr.
The Thermo Scientific^TM EA IsoLink^TM IRMS System has fundamentally improved analysis by EA-IRMS using temperature ramped gas chromatography with a single GC column and a patented helium management system that reduces cost per analysis. These innovative features open doors to push research boundaries at new levels, especially for the analysis of very small concentrations and on very high C/N and C/S ratio samples.

This presentation will principally focus on the advantages of using temperature ramped gas chromatography. Traditionally, gas chromatography in EA-IRMS employed a GC column held at an isothermal temperature as the gases eluted. However, using temperature ramped gas chromatography in the EA IsoLink IRMS System, a feature common in GC-MS and GC-IRMS, the temperature of the GC column can be quickly changed as analyte gases are eluting, improving peak separation, peak fidelity, analysis of very small sample amounts and precision of replicate measurements.

We will discuss these improvements in peak separation, background determination, troubleshooting of the combustion, pyrolysis and chromatographic processes, blank determination and analysis of very small sample concentrations. Our improved GC technique is illustrated in Figure 1, which shows a chromatogram of a NCS analysis on wood (C/S ratio of 7900:1) from a single sample drop. Complete baseline separation of each analyte is achieved with sound background correction and peak fidelity, including for very large (7000 μg C) and very small (11 μg N and 1 μg S) analyte amounts. For 5 replicate measurements on wood, δ¹³C = -24.10±0.06‰; δ¹⁵N = 3.20±0.23‰ and δ³⁴S = 5.92±0.26‰.

Bryozoan biota as a proxy for the climatic changes in Cenozoic of West Antarctica

Urszula Hara^1
1Polish Geological Institute-National Research Institute
Bryozoans in the marine and glacio-marine Cenozoic sedimentary sequences form a morphologically and taxonomically diversified biota in West Antarctica. During the late Early-late Eocene of the La Meseta Fm. they are dominated by hemispherical, multilamellar cyclostome cerioporines, cheilostome ascophoran lepraliellids and anascan microporoideans with a high number of a new taxa for the science, a great value for the austral biogeographical connections, as well as with considerable evolutionary interest, including the oldest stratigraphical records (Hara, 2001).

Bryozoans occur at least intermittently through the late Miocene-Pliocene glaciomarine Hobbs Glacier Formation of the James Ross Island group (Pirrie et al. 1997; Jonkers, 1998). The late Pliocene assemblage from the shallow-marine pectinid-rich biofacies preserved in the near-shore Pecten Conglomerate (= Cockburn Island Formation) of Cockburn Island in the James Ross Island area (NE Antarctic Peninsula) contains the abundance of the encrusting colonies.

The majority of the late Pliocene cheilostomes are known from the Mid-Late Cretaceous, the others are considered to have originated in the Paleogene (Eocene-Oligocene), evolving in the Antarctic region and becoming widespread through the Neogene to the Recent, along with one well-represented wholly Neogene Microporellidae family.

The distribution of the Recent bryozoans with a dominant ascophoran lepraliomorphs of Schizoporelloidea – the most richly represented superfamily as well as umbonulomorphs illustrate a dynamic evolution of the highly endemic Antarctic fauna. The bryozoan’s colonial growth-form could be used as a potential tool in interpretation of the different Cenozoic ecosystems and climatic regimes ranging from greenhouse to icehouse.

References

Hara, U. Palaeontologia Polonica, vol. 60, pp. 35-155.

Jonkers,  H.A. 1998. Newletters on Stratigraphy, 36, 63–76.

Pirrie D., Crame J.A. Lomas S.A. and Riding J.B. 1997. Cretaceous Research, 18, 109-137.

Elements of Eoarchean life trapped in mineral inclusions

Tue Hassenkam¹, Martin P. Andersson¹, Kim N. Dalby¹, David M. A. Mackenzie² and Minik T. Rosing^3
1Nano-Science Center, University of copenhagen, Denmark, ²Center for Nanostructured Graphene (CNG), Department of Micro- and Nanotechnology, Technical Univers, ³Natural History Museum of Denmark, University of Copenhagen, 1350, Denmark
Metasedimentary rocks from Isua, West Greenland (> 3.7 billion year old) contain ¹³C depleted carbonaceous compounds, with isotopic ratios consistent with a biogenic origin. Metamorphic garnet crystals in these rocks contain bands of carbonaceous material contiguous with carbon-rich sedimentary beds in the host rock, where carbon is fully graphitized. Here we studied carbonaceous inclusions armoured within garnet porphyroblasts by in-situ Infrared absorption on ~10^-21 m³ domains within these inclusions. The absorption spectra are consistent with carbon bonding to N and O and likely to phosphate. C-H or O-H bonds could not be detected. These results are consistent with biogenic organic material isolated for billions of years and thermally matured at temperatures around 500 ^oC. They therefore provide spatial characterization for potentially the oldest biogenic carbon relics in Earth’s geologic record.

References
Hassenkam, T., Andersson, M. P., Dalby, K. N., Mackenzie, D. M. A. & Rosing, M. T. Elements of Eoarchean life trapped in mineral inclusions. Nature 548, 78-81, doi:10.1038/nature23261

Sedimentology, stratigraphy and palaeoenvironments of the Miocene primate-bearing sequence in Inner Mongolia, China

Anu Kaakinen¹, Leena Sukselainen¹, Zhaoqun Zhang², Johanna Salminen³ and Mikael Fortelius^1
1Department of Geosciences and Geography, University of Helsinki, ²Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, ³Department of Physics, University of Helsinki
Central Inner Mongolia has been an area of great palaeontological interest since the beginning of the 20th century. Although the area has produced numerous diverse collections of Miocene faunas, fossil records from the early Miocene of Inner Mongolia are relatively rare.

Our field investigations in Damiao, Inner Mongolia have yielded more than 30 new fossiliferous localities, which have produced a rich mammalian fauna, including pliopithecid remains. We present a multidisciplinary study of the Damiao sequence, integrating sedimentological, stratigraphical, geochemical and diverse palaeontological data.

We have interpreted the Damiao sequence as the remains of a fluvio-lacustrine system comprising channels, subaerially exposed floodplains and ephemeral/marginal lacustrine environments. The bulk of the vertebrate fossils have been recovered from three main fossil horizons: The paleomagnetic results and faunal evidence suggest a correlation of lowermost fossil horizon producing relatively rich small mammal assemblage to the early Miocene, roughly in 20–21 Ma age range. The pliopithecid locality level represents latest middle Miocene and has an age estimate of about 12.1 Ma while the youngest localities with cervoids and abundant and diverse small mammal fauna represents the earliest late Miocene with an age estimate of about 11.6 Ma.

Hypsodonty, estimated mean annual precipitation, local sedimentology, and large mammal fossils suggest relatively humid and possibly more forested and wooded environments for the primate-bearing locality. This challenges the scenarios suggesting arid and highly seasonal conditions for Central Asia since Early Miocene.

References
Kaakinen, A., Abdul Aziz, H., Passey, B.H., Zhang, Z., Liu, L., Wang, L., Krijgsman, W. & Fortelius, M. 2015: Age and stratigraphic context of Pliopithecus and associated fauna from Miocene sedimentary strata from Damiao, Inner Mongolia, China. Journal of Asian Earth Sciences 100, 78–90.

Sukselainen, L., Kaakinen, A., Eronen, J.T.E., Passey, B.H., Harrison, T., Zhang, Z. & Fortelius, M. 2017: The paleoenvironment of the middle Miocene pliopithecid locality in Damiao, Inner Mongolia, China Journal of Human Evolution 108, 31–46.

Sukselainen, L., Peltonen, H., Kaakinen, A. & Zhang, Z. 2017: Small mammal taphonomy of three Miocene localities from Damiao, Nei Mongol, China. Vertebrata PalAsiatica 55, 71–88.

Zhang, Z., Kaakinen, A., Wang, L., Liu, L., Liu, Y. & Fortelius, M. 2012: Middle Miocene Ochotonids (Ochotonidae, Lagomorpha) from Damiao Pliopithecid locality, Nei Mongol. Vertebrata PalAsiatica 50, 281–292.

Sinemurian-Pliensbachian abundance and size changes in the calcareous nannofossil Schizosphaerella – relation to climatic and palaeoenvironmental change in the Paris Basin

Nicolas Thibault¹ and Peti
¹Leonie
Abundance and size changes in the calcareous nannofossil Schizosphaerella have been investigated through the Early Jurassic (late Sinemurian to early Toarcian) of the Sancerre-Couy core (Paris Basin). Measurements are compared to variations in CaCO₃ content, total organic carbon (TOC) content, and isotopic trends in carbon and oxygen. Our results confirm that Schizosphaerella was better adapted to proximal areas than coccoliths as expressed by the stepwise rise in abundance of Schizosphaerella, followed by a rise in abundance of coccoliths during the major transgression of the Sinemurian. The results show that changes in the size of Schizosphaerella were mostly a response to Early Jurassic temperature variations (icehouse and coolhouse versus-greenhouse conditions) but comparison to belemnite oxygen isotope data show that temperature alone cannot explain all the patterns observed in size changes. Biometry statistics suggest the presence of 3 main morphotypes. The large morphotype is present mostly during proximal, cool environmental conditions of the upper Sinemurian. The medium morphotype was adapted to more distal conditions and cool surface waters whereas the small morphotype is associated with warm episodes an higher nutriency.

                       POSTER PRESENTATIONS                    

The microstructure of Euselachian (Chondrichthyes) tooth and scales from Late Permian of Lithuania-Latvia Region

Darja Dankina-Beyer¹, Andrej Spiridonov¹ and Sigitas Radzevičius^1
1Department of Geology and Mineralogy, Vilnius University, M. K. Čiurlionio 21/27, LT03101, Vilnius,
The Late Permian palaeoichthyofauna of the Lithuanian-Latvian border Region is poorly known due to lack of the information and comparative isolated material from Southern Permian Basin. The studied region is located generally on the flat coastal zone of the northeastern shore of the Zechstein Sea (Dankina et al. 2017). The assemblages of the fish microremains such as teeth and scales of chondrichthyans and osteichthyans from Naujoji Akmenė Formation (northern Lithuania) and Alši, Kūmas, and Auce Formations (southern Latvia), Lopingian, Upper Permian were found.

Previous studies on tooth and scale enameloid microstructure provided a single crystallite enameoid (SCE) as a monolayer in the most primitive chondrichthyan taxa (Botella et al. 2009). However, the dental and dermal denticle microstructure of the Paleozoic ichthyofauna has yet to be investigated. We have studied the crushing tooth and some scales microstructure of the Late Permian chondrichthyans. As a result, the investigation with scanning electron microscope (SEM) has shown the presence of the crown and superficial cap of single crystallite enameloid of euselachian-type scales as well as tubular dentine on the Helodus sp. tooth.

References
–      Botella, H., Donoghue, P.C.J., Martínez Pérez, C., 2009. Enameloid microstructure in the oldest known chondrichthyan teeth. Acta Zoologica 90(1): 103-108.

–      Dankina, D., Chahud, A., Radzevičius, S., Spiridonov, A. 2017. The first microfossil of ichthyofauna from the Naujoji Akmenė Formation (Lopingian), Karpėnai Quarry, northern Lithuania. Geological Quaerterly 61(3): 602-610.

Palynological investigation of the late Pliocene to early Pleistocene proto-Gulf of Corinth, Greece

Gauti Trygvason Eliassen¹, Martin Muravchik¹, Rob Gawthorpe¹, Gunn Mangerud¹ and Gijs Henstra^1
1University of Bergen, Department of Earth Science
Rift basins have proven economically significant as hydrocarbon provinces and, furthermore, record the structural, sedimentary and climatic evolution of the basins and associated catchment areas. The aim of this study is to utilize palynological methods to constrain rift basin evolution and provide insight into eastern Mediterranean late Pliocene climate development.

In this study, we take a closer look at the active Corinth rift, Greece, whose early syn-rift deposits are spectacularly exposed on the northern Peloponnese peninsula. So far, research and existing literature has focused on the western part of the onshore stratigraphy, whereas the central and eastern areas have received less attention. The study area is the northern Sythas Valley, where late Pliocene to early Pleistocene deep-water deposits of the Rethi-Dendro Formation (RDF) are exposed in extensive cliff sections.

The RDF has been mapped using traditional field methods combined with digital outcrop data (LiDAR). Furthermore, three drill cores that cover c. 750 m of stratigraphy are being retrieved. Palynological analysis suggests a strong sedimentary facies dependence of the palynomorph assemblage. The findings of marine dinoflagellate cysts suggests periods of connectivity between the proto-Gulf of Corinth and the Mediterranean at an earlier stage than previously reported. The results may prove vital for understanding the structural evolution of the basin as they imply that by Late Pliocene time the northern margin of the rift had already migrated close to its present location.

Late Toarcian to Early Bajocian climate and environmental changes in Europe and East Greenland – geochemical records from calcite fossils and sediments

Jesper Allan Frederiksen¹, Suzanne Pultz¹, Gerd Dietl², Stéphane Bodin³, Peter Alsen⁴, Günther Schweigert⁵, Clemens Vinzenz Ullmann⁶ and Christoph Korte^1
1Department of Geology and Natural Resource Management, Østre Voldgade 10, 1350 København K, Denmark., ²Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany., ³University of Aarhus, Department of Geoscience, Høegh-Guldbergs Gade 2, 8000 Aarhus C, Denmark., ⁴GEUS, Geological Survey of Denmark and Greenland, Østre Voldgade 10, 1350 København, Denmark., ⁵Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany, ⁶Camborne School of Mines and Environment and Sustainability Institute, University of Exeter, UK
This study becomes the first author’s Master Thesis, and the aims are to use the isotope values from collected bulk rock samples and from pristine fossils to reconstruct climate and environmental fluctuations during the late Early and early Middle Jurassic (Late Toarcian–Bajocian) Middle European epicontinental Swabo-Franconian and Paris Basins, the French Subalpine Basin and the East Greenland Jameson Land Basin. Belemnite rostra and bulk rock samples were collected in SW Germany in Zell unter Aichelberg at the Pliensbach stream (upper Posidonienschiefer Fm., Jurensismergel Fm., lower Opalinuston Fm.), and in Balingen Zillhausen at the Wasserfall section (Opalinuston Fm.), and at the Roschbach section (Comptumbank, Eichberg Fm., and Subfurcatenoolith, Ostreenkalk Fm.) (see Quenstedt 1856-1858; Bloos et al., 2005). Coeval samples were taken from the La Baume section in SE France (Aalenian–Bajocian) (see De Baets et al., 2008), from different localities in Luxembourg, and from the Sortehat Fm. (only Aalenian) in Jameson Land, East Greenland (see Krabbe et al., 1994; Dam & Surlyk 1998; Koppelhus & Hansen 2003). All fossils were screened for diagenetic alteration (see Ullmann and Korte, 2015) using the Scanning Electron Microscope (SEM) and element ratios. Sr/Ca vary between 0.533 and 2.595 mmol/mol and Mn/Ca between 0.002 and 29.661 mmol/mol. Oxygen (vary between – 3.41 and 4.09 ‰ PDB) and the carbon isotope values (-11.11 and 1.90 ‰ PDB) were recently measured and altered data will be culled as the next research step. Organic carbon isotope measurements on bulk rock samples are currently in progress.

References
Bloos, G.; Dietl, G.; Schweigert, G. 2005: Der Jura Süddeutschlands in der Stratigraphischen Tabelle von Deutschland 2002, Newsletter Stratigraphy 41, 263-277.

Dam, G. & Surlyk, F. 1998: Stratigraphy of the Neill Klinter Group; a Lower – lower Middle Jurassic tidal embayment succession, Jameson Land, East Greenland. Geology of Greenland Survey Bulletin 175, 80 pp.

De Baets, K.; Cecca, F.; Guiomar, M.; Verniers, J. 2008: Ammonites from the latest Aalenian—earliest Bathonian of La Baume (Castellane area, SE France): palaeontology and biostratigraphy, Birkhäuser Verlag, Swiss Journal of Geoscience 101, 563-578.

Koppelhus, E. & Hansen, C.F. 2003: Palynostratigraphy and palaeoenvironment of the Middle Jurassic Sortehat Formation (Neill Klinter Group), Jameson Land, East Greenland, Geological Survey of Denmark and Greenland, Bulletin 1, 777–811

Krabbe, H.; Christiansen, F.G.; Dam, G.; Piasecki, S.; Stemmerik, L. 1994: Organic geochemistry of the Lower Jurassic Sortehat Formation, Jameson Land, East Greenland. Rapport Grønlands Geologiske Undersøgelse 164, 5–18.

Quenstedt, F.A. 1856-1858: Der Jura, Laupp-Verlag, Tübingen.

Ullmann, C.V. & Korte, C. 2015: Diagenetic alteration in low-Mg calcite from macrofossils: A review. Geological Quarterly 59 (1), 3–20.

Surface analyses of fossil leaves

Magnus A. R. Harding¹ and Tais W. Dahl^1
1Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen
Recent studies show that the metallome and chemical composition of living plants depend on the geology as well as nutritional quality of the soils in which the plants grew (e.g. Husted et al. 2004; Laursen et al. 2011; Mie et al. 2014). Few studies, however, have examined the chemical makeup of fossil plant material. In this study, μXRF, ToF-SIMS, LA-ICP-MS and FTIR techniques are applied to a fossil conifer (Cupressaceae) from the Naujât Member, West Greenland in an attempt to identify and distinguish pristine organic matter preserved as well as the diagenetic history of the fossil. Moreover, the strengths and weaknesses of the various analytical techniques are compared. Organic matter within the fossil was identified, but it is uncertain whether it has a pristine or a bacterial origin. The Naujât conifer fossil is permineralized in calcite with small spots of iron sulphides present mainly where the fossil is thickest. The fossil is embedded in a siderite concretion formed in kaolinite-rich sediment. Based on the observations, a model for the fossilization of the plant is proposed.

References
Husted, S., Mikkelsen, B. F., Jensen, J., Nielsen, N. E. 2004: Elemental fingerprint analysis of barley (Hordeum vulgare) using inductively coupled plasma mass spectrometry, isotope-ratio mass spectrometry and multivariate statistics. Analytical and Bioanalytical Chemistry 378, 171–182.

Laursen, K. H., Schjoerring, J. K., Olesen, J. E., Askegaard, M., Halekoh, U., Husted, S. 2011: Multielemental Fingerprinting as a Tool for Authentication of Organic Wheat, Barley, Faba Bean, and Potato. Journal Of Agricultural And Food Chemistry 59, 4385–4396.

Mie, A., Laursen, K. H., Åberg, K. M., Forshed, J., Lindahl, A., Thorup-Kristensen, K., Olsson, M., Knuthsen, P., Larsen, E. H., Husted, S. 2014: Districimation of conventional and organic white caggabe from a long-term field trial study using untargeted LC-MS-based metabolomics. Analytical and Bioanalytical Chemistry 406, 2885–2897.

Carinodens – a new addition to the Late Cretaceous mosasaur fauna of Denmark

Jesper Milàn¹, John W.M. Jagt², Johan Lindgren³ and Anne S. Schulp^2
1Geomuseum Faxe, Denmark, ²Natuurhistorisch Museum Maastricht, The Netherlands, ³Department of Geology, Lund University, Sweden
The small durophagous mosasaurine mosasaur (Reptilia, Mosasauridae) genus Carinodens is exceedingly rare in north European chalk deposits, with published finds limited to a small number of shed tooth crowns and two partial dentaries from The Netherlands and Belgium, all assigned to Carinodens belgicus. A newly discovered isolated, shed tooth crown from the UNESCO world heritage site of Stevns Klint expands the known geographical distribution of another species, C. minalmamar, first described from Morocco, to Denmark. The specimen was found within the uppermost metres of the Maastrichtian chalk deposits, thereby placing it within the last 50.000 years of the Cretaceous. The new tooth crown represents the northernmost occurrence of the genus Carinodens. Previous finds of mosasaur dental and skeletal materials from Denmark have all been assigned to the hypercarnivorous mosasaurids Mosasaurus hoffmannii and Plioplatecarpus sp. Thus, the new specimen provides important new information on ecological niche partitioning amongst large marine reptiles during the latest Maastrichtian.

Biostratigraphy and palaeoecology of calcareous nannofossils in the Lower Cretaceous Munk Marl Bed, Danish North Sea

Sarah D. Møller¹, Emma Sheldon² and Jan Audun Rasmussen^3
1Department of Geosciences and Natural Resource Management, Københavns Universitet, ²GEUS, Geological Survey of Denmark and Greenland, ³Fossil- og Molermuseet, Museum Mors
The Lower Cretaceous Munk Marl Bed of the Tuxen Formation (Danish Central Graben) marks a change in the depositional environment within a chalk unit. Here we investigate the calcareous nannofossils from this interval of the Danish Boje-2C well with emphasis on biostratigraphy and palaeoecology to better understand the pelagic environment at the time of deposition. A total of seventy-two samples were analysed from the well. The samples correlate to the upper Lower Barremian nannofossil zones BC14 and LK20B. An acme of nannoconid ‘tops’ is proposed as a new biostratigraphical event characterising the middle part of the Munk Marl Bed. High abundances of thermophile taxa suggest warm surface water conditions at the time of deposition. Indicators of increased fertility show particularly low abundances indicating a decrease in surface water fertility, presumably related to an increased detrital input. Correspondence analysis ordinates samples in relation to identified palaeoecological proxies and reflects palaeotrophic levels in the surface water within the section. The analysis shows that the calcareous nannofossils indicate a period of more oligotrophic surface water in the middle of the section.

Middle Jurassic palaeoenvironmental events in Europe – evidence from palynology and carbon and oxygen isotopes

Suzanne Pultz¹, Jesper Allan Frederiksen¹, Sofie Lindström², Stéphane Bodin³ and Christoph Korte^1
1Department of Geosciences and Natural Ressource Management (IGN), University of Copenhagen, DK, ²Geological Survey of Denmark and Greenland (GEUS), DK, ³Deparment of Geosciences, Aarhus University, DK
During the early Middle Jurassic, several biotic and climatic changes took place. A major event occurred at the Aalenian to Bajocian transition, and is associated with a negative carbon isotope excursion in carbonate and organic matter (Bartolini et al., 1996; Hesselbo et al., 2003). This negative excursion is, in turn, succeeded in the Early Bajocian by a poorly understood positive carbon isotope excursion, associated with floral and faunal turnovers (Sucheras-Marx et al., 2015; Bodin et al., 2017). In contrast, dinoflagellates underwent a major evolution and radiation from the Late Aalenian to Early Bathonian, and changes in relative sea level are thought to have controlled the stratigraphic pattern of dinoflagellate cysts (Wiggan et al., 2017). These paleoenvironmental perturbations are also reflected in the carbon isotopes of terrestrial organic matter and marine carbonate, with lighter values in the marine palynofacies (Hesselbo et al., 2003). In the present study, currently in progress palynological and isotopic investigations of latest Toarcian to Bajocian samples from three different regions in Europe – (1) SE France (La Baume section), (2) SW Germany (sections in Zell unter Aichelberg at the Pliensbach stream, and Balingen Zillhausen at the Wasserfall and at the Roschbach), and (3) in S Sweden (Vilhelmsfält core) (Guy 1971) – are presented. The aim is to document the presence and abundance of marine and terrestrial palynomorphs as well as to identify carbon and oxygen isotopes trends in the investigated successions in order to replace them within the framework of Middle Jurassic climatic and environmental changes.

References

Bartolini, A.; Baumgartner, P.; Hunziker, J. 1996: Middle and Late Jurassic carbon stable-isotope stratigraphy and radiolarite sedimentation of the Umbria-Marche Basin (Central Italy), Eclogae Geologicae Helvetiae, 89, pp. 811-844.

Bodin, S.; Hönig, M. R.; Krencker, F.-N.; Danish, J.; Lahcen, Kabiri. 2017: Neritic carbonate crisis during the Early Bajocian: Divergent responses to a global environmental perturbation, Palaeogeography, Palaeoclimatology, Palaeoecology, 468, Elsevier, 184-199.

Guy, D. J. E. 1971: Palynological investigations in the Middle Jurassic of the Vilhelmsfält boring, Southern Sweden, The Institutes of Mineralogy, Palaeontology and Quaternary Geology, University of Lund, Sweden, 168, 109 pp.

Hesselbo, S. P.; Morgans-Bell, H. S.; McElwain, J. C.; McAllister Rees, P.; Robinson, S. A; Ross, C. E. 2003: Carbon-cycle perturbation in the Middle Jurassic and accompanying changes in the terrestrial paleoenvironment, The Journal of Geology, 2003, volume 111, p. 259-276.

Suchéras-Marx, B.; Mattioli, E.; Giraud, F.; Escarguel, G. 2015: Paleoenvironmental and paleobiological origins of coccolithophorid genus Watznaueria emergence during the late Aalenian-early Bajocian, Paleobiology, 41 (3), pp. 415-435.

Wiggan, N. J.; Riding, J. B.; Franz, M. 2017: Resolving the Middle Jurassic dinoflagellate radiation: The palynology of the Bajocian of Swabia, southwest Germany, Palaeobotany and Palynology, 238, Elsevier, 55-87.