Hans Egger

Global dinoflagellate event associated with the late Paleocene thermal maximum

The late Paleocene thermal maximum, or LPTM (ca. 55 Ma), represents a geologically brief time interval (∼220 k.y.) characterized by profound global warming and associated environmental change. The LPTM is marked by a prominent negative carbon isotope excursion (CIE) interpreted to reflect a massive and abrupt input of 12 C-enriched carbon to the ocean-atmosphere reservoir, possibly as a result of catastrophic gas-hydrate release, on time scales equivalent to present-day rates of anthropogenic carbon input. The LPTM corresponds to important changes in the global distribution of biota, including mass extinction of marine benthic organisms. The dinoflagellate cyst record indicates that surface- dwelling marine plankton in marginal seas also underwent significant perturbations during the LPTM. We report on the dramatic response of representatives of the genus Apectodinium from two upper Paleocene–lower Eocene sections in the Southern (New Zealand) and Northern (Austria) Hemispheres, where the dinoflagellate records are directly correlated with the CIE, benthic foraminifera extinction event, and calcareous nannofossil zonation. The results indicate that the inception of Apectodinium -dominated assemblages appears to be synchronous on a global scale, and that the event is precisely coincident with the beginning of the LPTM. Apectodinium markedly declined in abundance near the end of the LPTM. This Apectodinium event may be associated with (1) exceptionally high global sea-surface temperatures and/or (2) a significant increase in marginal-marine surface-water productivity. Such a globally synchronous acme of dinoflagellate cysts is unprecedented within the dinoflagellate cyst fossil record.

Tectonic and climatic control of Paleogene sedimentation in the Rhenodanubian Flysch basin (Eastern Alps, Austria)

Abstract The Paleocene to lowermost Eocene formations of the Rhenodanubian Flysch were deposited in an abyssal environment at the continental rise to the south of the European Plate. The pattern of paleocurrents indicates a number of small distributary systems for the turbiditic material that entered the basin from the north and was deflected to the east and to the west. Heavy mineral assemblages in the turbidites suggest the erosion of medium-grade metasediments in the Danian and the progressive erosion of underlying metamorphic magmatic rocks in the Thanetian and Ypresian. The most obvious sedimentary event is the breakdown in turbidite sedimentation during the late Danian to the early Thanetian. Remarkably, this starvation of turbidites is associated with high values of chlorite in the clay mineral assemblages of interturbidite shales, indicating increased mechanical erosion of the adjoining land areas. Tectonic uplift of these areas and associated block faulting and tilting is assumed to be responsible for this increase in erosion as well as for the synchronous cutting off of the basin from the source area of the turbidites. This tectonic activity is related to the onset of the collision of the European and the Adriatic Plates. A second major event documented in the Paleogene record is the change from a predominantly siliciclastic system to a carbonate system in the latest Thanetian. Associated with the global negative carbon isotope excursion (CIE) in the upper part of calcareous nannozone NP9, calcareous mudturbidites become the prevailing rock type. Eutrophication of surface waters is indicated by acmes of diatoms, radiolaria and dinoflagellates at the level of the CIE. Together with slightly increased values of kaolinite in the clay mineral assemblages of interturbidite shales, this can be interpreted as a result of increased continental run-off due to high precipitation rates in a humid climate. The top of the increased kaolinite input is poorly constrained because of a very high input of smectite due to volcanic activity in sub-zone NP10a. This igneous activity is assigned to the opening of the Northern Atlantic Ocean and has no geodynamic relevance for the Rhenodanubian Basin.

Paleoproductivity of the northwestern Tethyan margin (Anthering section, Austria) across the Paleocene-Eocene transition

Sediments in the expanded Anthering Section at the northwestern Tethyan margin were deposited in an abyssal environment, at the continental rise to the south of the European plate. The section contains deposits from calcareous nannoplankton Zones NP9 and NP10 and displays the global negative carbon isotope excursion (CIE) in the upper part of Zone NP9. Associated with the CIE is a strong three-fold increase in the rate of hemipelagic sedimentation. This suggests an increased input of siliciclastic suspended material into the basin, which is indicative of enhanced continental runoff at that stratigraphic level. Concurrent acmes of siliceous plankton and dinoflagellate cysts indicate that a high input of dissolved nutrients affected even open marine settings and caused eutrophication of surface waters. The associated high flux of organic carbon to the seafloor resulted in oxygen-depleted conditions and caused the total extincton of benthic faunas. However, impoverished foraminifera faunas indicate that a change of ecological conditions started shortly before the CIE. 133 Egger, H., Fenner, J., Heilmann-Clausen, C, Rogl, F., Sachsenhofer, R.F., Schmitz. B., 2003, Paleoproductivity of the northwestern Tethyan margin (Anthering Section, Austria) across the Paleocene-Eocene transition, in Wing, S.L., Gingerich, P.D., Schmitz, B., and Thomas, E., eds., Causes and Consequences of Globally Warm Climates in the Early Paleogene: Boulder, Colorado, Geological Society of America Special Paper 369, p. 133–146.

From shelf to abyss: Record of the Paleocene/Eocene-boundary in the Eastern Alps (Austria)

In the Eastern Alps (Austria) several marine successions, which were deposited ranging from shallow shelf to bathyal slope and abyssal basin, provide detailed records across the Paleocene/Eocene-boundary. These records indicate a two-step event starting with a prominent sea-level fall and followed by climatic changes. At the northern and southern shelves that fringed the Penninic Basin, the shallow-water sedimentary records are incomplete across the Paleocene/Eocene transition. Erosional surfaces indicate a major sea-level drop, which was terminated by an early Eocene (Ypresian) transgression within calcareous nannoplankton Zone NP12. As a proxy for the onset of this sea-level fall a strong increase in the terrestrially-derived input into the Penninic Basin can be used. The abyssal Anthering section from the northern part of the basin comprises a complete succession from NP9 to the upper part of NP10 (upper Thanetian-lower Ypresian). The thickest turbidite beds of this 250 m thick succession appear just before the carbon isotope event in the upper part of zone NP9, which is used to recognize the Paleocene/Eocene-boundary. A major lithological change from a sandstone-dominated facies to a claystone-dominated facies occurs at the onset of the carbon isotope event. This might be the result of a climatic change, resulting in increased intra-annual humidity gradients and increased physical erosion of the hinterland. Consequently, mainly fine-grained suspended material would have come into the basin and caused an increase in hemipelagic sedimentation rates by about a factor of 6. A similar value has been calculated for the bathyal Untersberg section, which was deposited on the southern slope of the basin, where an increased input of siliciclastic material is associated with a carbonate dissolution event during the carbon isotope event. At the southern shelf, a stratigraphic gap within the Gosau Group in the Krappfeld area (Carinthia) comprises the Maastrichtian and Paleocene. After a sea-level rise nummulitic marlstone and limestone were deposited in the lower part of zone NP12. Since the northern and southern shelves of the Penninic Basin belonged to different tectonic domains, with different potentials of crustal subsidence, the temporal similarity of sea-level changes on both shelves in the latest Paleocene and earliest Eocene suggests that these sea level fluctuations were mainly eustatic in origin.

The Anthering outcrop (Austria), a key-section for correlation between Tethys and northwestern Europe near the Paleocene/Eocene boundary

A section in the Rhenodanubian Flysch at Anthering, near Salzburg, Austria, records important dinoflagellate events which are also recognized in NW Europe, where they have proved to be reliable biostratigraphical tools in the Paleocene/Eocene boundary interval lacking calcareous microfossils. It is the first direct biostratigraphical correlation between NW Europe and the Tethys in this interval. The Austrian dinoflagellate record suggests that some dinoflagellate events near the Paleocene/Eocene boundary are probably widely recognizable. The calcareous nannofossils in the Anthering section enable a direct calibration between the dinoflagellate events and the standard calcareous nannofossil zonation (Egger et al. in press). In ascending order, the most important dinoflagellate events are: 1) A strong acme of Apectodinium spp. (exceeding 60% of the total dinoflagellate assemblage in some samples) in upper NP9, contrasting to percentages generally between 10 and 25 in the sections above and below. The acme coincides with a negative shift in δC interpreted to probably represent the global carbon isotopic excursion (CIE) (Egger et al. in press). 2) The regular occurrence of Apectodinium augustum approximately restricted to the same interval as the acme of the genus. 3) The first appearance of the genus Wetzeliella in the upper part of NP10. The genus is represented by two species: one is identical or close to the NW European species W. lobisca or W. lunaris. The other one is W. unicaudalis, which is more common. It has formerly been recorded in the North Atlantic Basque Basin (Caro 1973), but not in NW Europe. An interval with bentonite layers occurs between the LAD of A. augustum and FAD of Wetzeliella. The main ash phase of the North Sea Basin occurs in a similar position relative to the same dinoflagellate events. This first-order calibration between NW European dinoflagellate events and the standard nannofossil zonation provides independent evidence for the position of sections from the type areas of the Sparnacian and Ypresian stages in the global stratigraphical schemes. The occurrence of the calcareous nannofossil Tribrachiatus digitalis relative to the dinoflagellate events is similar at Anthering (Egger et al. in press) and in the basement bed of the London Clay (Berggren & Aubry 1998). The new data seem to confirm the bio-chronostratigraphical position of these sections as hitherto interpreted by most workers mainly on the basis of a combination of magnetostratigraphy, tephra-correlation, and absolute datings.

The missing link in the evolutionary origin of the foraminiferal genus Hantkenina and the problem of the lower-middle Eocene boundary

The initial appearance of the planktonic foraminiferal genus Hantkenina has been used for about fifty years to recognize the base of the Lutetian and middle Eocene. However, probably as a result of incomplete stratigraphic records, discrepant ranges of Hantkenina have been reported by various investigators at many Eocene sections. Here we report the first complete evolutionary transition from Clavigerinella to Hantkenina , from the northwestern Tethyan deep-water section at Holzhausl (Salzburg, Austria). A newly discovered species, Hantkenina nov. sp., is the link between Clavigerinella caucasica and Hantkenina mexicana . This finding unequivocally heralds the initial entry of Hantkenina , which is correlated to the upper part of calcareous nannoplankton Subzone NP15b ( Sullivania gigas Subzone), to be defined. This indicates a mismatch of ∼4.5 m.y. between the base of the Lutetian at the type locality, which has been placed within Subzone NP14b, and the first appearance datum of Hantkenina . Consequently, the first occurrence of Hantkenina can no longer be used as a marker for the base of the middle Eocene.

NAA of the “Minoan pumice” at Thera and comparison to alluvial pumice deposits in the Eastern Mediterranean region

Neutron activation analysis was used to determine up to 30 elements in the pumice layers from the “Minoan eruption” at Thera (Santorini, Greece). Mt Pilato (Lipari, Italy) and in alluvial pumice from coasts of the Eastern Mediterranean region. The morphologically well distinguishable layers of the “Minoan pumice” were found to be of nearly similar composition in respect to the elements determined and their distribution patterns could therefore be used to identify a sample as Santorinian or not. Additionally, this method was applied to pumice lumps found during archaeological excavations in the Nile delta, Egypt. The results showed that two of the three Egyptian samples are products of the Minoan eruption at Thera and therefore chronologically useful. A second group of pumices collected at Antalya (Turkey), Crete (Greece) and also in Egypt was found to have a distinctly different composition and is therefore related to another volcanic event.

LM and SEM investigations of pollen from PETM and EECO localities of Austria and Great Britain: new findings of Atherospermataceae, Annonaceae, Araceae and Arecaceae from the Lower Eocene

Fossil pollen from three Lower Eocene localities was investigated by LM and SEM: The Palaeocene–Eocene Thermal Maximum (PETM) section at St Pankraz (Salzburg), three Brixton drill cores covering the PETM and the Early Eocene Climate Optimum locality at Krappfeld. Some pollen taxa found have been affiliated to Laurelia, today a southern hemispheric Atherospermataceae unknown from Europe, to two Annonaceae lineages, such as the African Monodora clade and a probable precursor of the old world Fenerivia/Maasia clades, thus representing two taxa not previously reported from the fossil record. Further two wetland associated Araceae (Limnobiophyllum and Lysichiton) are present as well as various Arecaceae, including not only previously described Salaccinae and Calaminae/Plectocomiinae, but also undocumented Bactridinae, Elaeidinae (both Cocoseae), and Coryphoideae and Arecoideae, although pollen from the latter two subfamilies could not be assigned in more detail.

The basal Lutetian Transgression on the Tethyan shelf of the European craton (Adelholzen beds, Eastern Alps, Germany)

The middle Eocene Adelholzen beds were deposited on the northern part of the Tethyan shelf of the European Plate. In the Eastern Alps, the Wimmern section near Teisendorf (Germany) is the only known outcrop exposing the basal unconformity of this sequence. The outcrop comprises an 8 m thick condensed transgressive shallow marine succession characterized by glauconite-rich weakly consolidated greensand and mudstone containing abundant larger benthic foraminifera. It spans the lower part of calcareous nannoplankton Zone NP15 (Sub-Zones NP15a and lower part of NP15b), planktonic foraminifera Sub-Zone E7b and Zone E8 partim and the upper part of shallow benthic Zone SBZ13. The landward migration of the paleo-shoreline was not an effect of flexural downbending of the European Plate but can be correlated to the major unconformity at the base of eustatic supercycle TA3. The onset of this sea-level rise was in the latest part of Biochron NP14b and almost coincided with the NP14b/NP15a-boundary.

Deep-sea sedimentation and paleoproductivity in the Paleogene of a Tethyan basin

In the area of Salzburg the Paleogene sediments of the Rhenodanubian flysch attain a thickness of approximately 450 m. These sediments were deposited in an abyssal environment below the calcite compensation depth and they comprise the complete Paleocene and the Ypresian (up to NP11). A composite section was constructed from two outcrop-groups located in the surrounding of the village of Anthering. Predominantly, the older part of the section (Danian) is built up by turbidites which often show Bouma-cycles. Only minor amounts of hemipelagic claystone occur. By far smectite is the most common clay mineral, followed by illite, chlorite, and kaolinite. The turbidites can be attributed to a small deep-sea fan which had its feeder channel 30 km east of the studied outcrops (Egger in prep.). The material of the turbidites was supplied from the southern part of the European plate which was located north of the flysch basin. The deep-sea fan was abandoned within nannoplankton Zone NP3 or NP4 and its deposits were covered by 50 m of claystone (Strubach-Tonstein) with only a few intercalated turbidite layers. It is noteworthy that the base of this prominent lithological shift seems to be coeval with the beginning of the Selandian. Sedimentation of the Strubach-Tonstein ended within Zone NP8. Clay-mineral composition of the StrubachTonstein is characterized by high contents of chlorite and illite which are indicating increased mechanical erosion in the source area whilst no kaolinite was observed in these samples. This erosion is seen as an effect of strong tectonic movements within the European plate in the middle Paleocene which caused inversion and uplifting of major basement blocks at distances up to 1300 km to the north of the present Alpine deformation front (e.g. Ziegler 1987). In the Alpine foreland these deformations gener-