Lowermost Oligocene Research Articles

Sedimentology and chronostratigraphy of the Apt Basin, Southeastern France: lacustrine response to late Paleogene cooling and regional rifting

The Apt Basin, sub-basin of the wider Manosque Basin of southeastern France, contains deposits of Eocene-Oligocene lake systems that were part of a broader network of evaporative lakes and lagoons spread across the European Cenozoic rift system. The onset and mechanisms of subsidence in the rift system, the interconnectivity of these lakes, and their response to the transition into the Oligocene icehouse are poorly understood. This study aims to clarify these points by examining the stratigraphy and depositional environments in the Apt Basin. We correlate and date Eocene to lowermost Oligocene geological units using a basin-wide facies model combined with sedimentological and geochronological approaches. We show the existence of three lacustrine phases, each separated by complete lake drying events: (1) an Ypresian (?) − Lutetian lake-marsh system dominated by palustrine carbonates; (2) a Bartonian (?) − Priabonian siliciclastic fluvio-deltaic and saline lake system; and (3) a lower Rupelian saline carbonate lake system. The presence of a lake system during the Ypresian (?) − Lutetian suggests an onset of basin subsidence before most other basins of the rift system in southeastern France, and is associated with the late Pyrenean deformation phase. The initiation of the second lacustrine phase marks the beginning of E-W extension and the formation of the Apt Basin as an individual horst & graben system. Based on facies distribution, we demonstrate the hydrological isolation of the Apt Basin from other basins and the improbability of any marine connection during the first two phases. This isolation is less certain for the third phase. We show a close synchronicity between the second lake drying event and the Eocene-Oligocene Transition. The third lacustrine phase, dominated by carbonate production and low siliciclastic input, is interpreted as reflecting a long-term decrease in surface runoff associated with the fall into the Oligocene icehouse.

Chemical composition of detrital chrome spinel and clinopyroxene from the Middle Eocene to lowermost Oligocene sandstones of central Iran (Nain area): Constraints on ophiolite provenance

Studies of relict Upper Cretaceous obducted ophiolites provide information on the evolution of the Neotethys suture belts in central Iran. Studies of the sediment derived from their erosion will complement this information by addressing questions related to sandstone provenance, ophiolite emplacement history, and, perhaps most importantly, the mode and timing of their erosion. The ca. 3200 m thick Middle Eocene to lowermost Oligocene fine- to medium-grained siliciclastic beds of the Akhoreh Formation are superbly exposed along the western border of the Central-East Iranian Microcontinent. They cover the northeastern flank of the Cretaceous Nain ophiolite mélange massif and lie adjacent to the Paleogene Urmieh–Dokhtar Magmatic Arc. The common occurrence of chrome (Cr)-spinel in the sandstones indicates the presence of mafic to ultramafic rocks in the source region. However, the timing, extent and nature of contributions of the potential source rocks to the sedimentary succession are not well understood. We conducted a petrographic and chemical compositional study of Cr-spinel in samples of Akhoreh Formation sandstones to outline the type of ocean lithospheric source. Our results document variable Cr# (0.09 to 0.79) and Mg# (0.21 to 0.88) while Fe3+ and TiO2 (average 0.12 wt%) are generally low. The wide range of Cr# and Mg# indicates provenance from a variety of (ultra-)mafic rock types, including supra-subduction peridotites and partially volcanic rocks of an arc-forearc setting. Cr-spinels are chemically similar to those of the lherzolites, harzburgites and dunites of the Nain ophiolite. While 70 % of the Cr-spinel have Cr# > 0.6, suggesting a harzburgitic peridotite provenance, the minimum Cr# < 0.4, observed in the samples from the base of the succession, were likely sourced from lherzolite. The chemical composition of detrital clinopyroxene grains shows high SiO2 (52.76 wt%), CaO (20.15 wt%), and MgO (16.36 wt%), while FeO has moderate (6.03 wt%), Al2O3 has low (2.23 wt%), and TiO2 has very low (0.25 wt%) concentrations (commonly augite and diopside), indicative of crystallization from subalkaline magma in an arc setting. The provenance data trace the erosion history of the obducted ophiolite and indicate that the Nain supra-subduction ophiolite supplied detritus to the Akhoreh Basin northwards from the Middle Eocene to the earliest Oligocene.

The second oldest representative of the genus Aeshna (Odonata: Aeshnidae) found in the lowermost Oligocene of Luberon (France) and revealed by UV light

ABSTRACT Aeshna caseneuvensis sp. nov., the second oldest representative of the genus Aeshna, is described and figured from the lowermost Oligocene of Luberon in southeastern France. The oldest described species in this genus is from the uppermost Eocene of Colorado in USA. Their occurrence in very distant areas in an interval of time of less of five millions years strongly suggests that the genus is older, possibly appearing during the middle Eocene, as it is still unknown in the early Eocene odonate faunas. The specimen could be studied thanks to a technique of photograph under UV light newly developed by one of us (RG).

The Cenozoic Malaguide Basin from Sierra Espuña (Murcia, S Spain): An Example of Geological Heritage

The Cenozoic Malaguide Basin from Sierra Espuña (Internal Betic Zone, S Spain) due to the quality of outcropping, areal representation, and continuity in the sedimentation can be considered a key-basin. In the last 30 years, a large number of studies with very different methodological approaches have been done in the area. Models indicate an evolution from passive margin to wedge-top basin from Late Cretaceous to Early Miocene. Sedimentation changes from limestone platforms with scarce terrigenous inputs, during the Paleocene to Early Oligocene, to the deep basin with huge supplies of turbidite sandstones and conglomerates during the Late Oligocene to Early Miocene. The area now appears structured as an antiformal stack with evidence of synsedimentary tectonics. The Cenozoic tectono-sedimentary basin evolution is related to three phases: (1) flexural tectonics during most of the Paleogene times to create the basin; (2) fault and fold compartmentation of the basin with the creation of structural highs and subsiding areas related to blind-fault-propagation folds, deforming the basin from south to north during Late Oligocene to Early Aquitanian times; (3) thin-skin thrusting tectonics when the basin began to be eroded during the Late Aquitanian-Burdigalian. In recent times some works on the geological heritage of the area have been performed trying to diffuse different geological aspects of the sector to the general public. A review of the studies performed and the revisiting of the area allow proposing different key-outcrops to follow the tectono-sedimentary evolution of the Cenozoic basin from this area. Eight sites of geological interest have been selected (Cretaceous-Cenozoic boundary, Paleocene Mula Fm, Lower Eocene Espuña-Valdelaparra Fms, Middle Eocene Malvariche-Cánovas Fms, Lowermost Oligocene As Fm, Upper Oligocene-Lower Aquitanian Bosque Fm, Upper Oligocene-Aquitanian Río Pliego Fm, Burdigalian El Niño Fm) and an evaluation has been performed to obtain four parameters: the scientific value, the educational and touristic potential, and the degradation risk. The firsts three parameters obtained values above 50 being considered of “high” or “very high” interest (“very high” in most of the cases). The last parameter shows always values below 50 indicating a “moderate” or “low” risk of degradation. The obtained values allow us considering the tectono-sedimentary evolution of this basin worthy of being proposed as a geological heritage.

The carnivoran-like insectivore Butselia Biveri Quinet &amp; Misonne, 1965 (Mammalia, Plesiosoricidae) from the lowermost Oligocene of Europe

Plesiosoricidae is a small extinct family of soricomorphan insectivores distributed from the Early Eocene to the Late Miocene on the three continents of the Northern Hemisphere. One of two known plesiosoricid subfamilies is represented by the particular Eurasian subfamily Butseliinae. Here we describe new dental and postcranial elements of Butselia biveri, the type-species of the genus Butselia from the lowermost Oligocene of Belgium. The specialized anterior dentition shows a strong caniniform i2 while the upper and lower molars show a remarkable convergent evolution with early carnivorans, especially the small Early Eocene miacids. Tarsal bones of Butselia biveri are also identified and described, suggesting a closely relationship with Nyctitheriidae but also indicating some convergent features with small scansorial carnivorans.

Benthic foraminiferal turnover at the Eocene-Oligocene transition in the Caltavuturo Formation cropping out near Santa Cristina Gela (Sicily)

A qualitative and quantitative study was carried out on the benthic foraminiferal assemblages from the upper Eocene to lower Oligocene of a section of the Caltavuturo Formation exposed near Piana degli Albanesi (northwestern Sicily). The recognized taxa are evaluated in terms of their ecology and bathymetric interpretation. Biostratigraphic constraints are defined combining both nannofossils and planktic foraminifers biozonations. The planktic-benthic foraminiferal ratio allowed the reconstruction of water depth variations. Atotal of 48 benthic foraminiferal taxawere extracted from the samples. The benthic assemblages and the P/(P+B) ratio indicate a lower to middle bathyal depositional depth, although an abrupt drop of sea level of about 140 m is recorded across the suspected Eocene-Oligocene transition. Calcium carbonate content decreases upsection, suggesting an increase in terrigenous supply in the lowermost Oligocene.

A fossil heron from the early Oligocene of Belgium: the earliest temporally well‐constrained record of the Ardeidae

We describe the earliest temporally well‐constrained fossil that can be assigned to the Ardeidae (herons), from the lowermost Oligocene (32.0–33.0 million years ago) of Belgium. The specimen, a partial tarsometatarsus, belongs to a small species and is described as Proardea? deschutteri n. sp. It exhibits the characteristic tarsometatarsus morphology found in extant heron species, but a confident assignment to one of the ardeid subclades is not possible and even the assignment of the new fossil species to the crown group (the clade including the extant species) cannot be established. The fossil indicates a divergence of herons from their sister taxon by at least the earliest Oligocene, and current paleontological data suggest that herons arrived in Europe shortly after a major faunal turnover at the Eocene/Oligocene boundary. We consider that dispersal is the likely reason for the sudden appearance of herons in the earliest Oligocene of Europe but it is uncertain from where exactly this took place, with Asia and Africa being among the candidate areas.

Paleobiogeography of the fossil box crab Calappilia (Brachyura: Calappidae) with a new species from the Eocene-Oligocene of Florida, USA

Members of the family Calappidae, or box crabs, date back to at least the Eocene, with Calappilia being the most species-rich calappid genus in the fossil record. The European species of Calappilia were reviewed recently, but less work has been done lately on the American species. We describe Calappilia calculosa n. sp. based on carapaces originating from the uppermost Eocene to lowermost Oligocene Rotularia vernoni Zone (Priabonian-Rupelian) in Suwannee County, Florida, USA. The new species is the youngest member of the genus in North America thus far. We further discuss some other occurrences of Calappilia that includes reassigning Calappilia ocalanus (Ross, Lewis and Scolaro, 1964) to Calappa , in part to better interpret the paleobiogeography of Calappilia . A worldwide paleobiogeographic analysis of Calappilia suggests that the genus first appeared in North America or Europe in the early Cenozoic. Rapid dispersal and radiation seem to have occurred in the Eocene because Calappilia is also reported from Eocene sediments of the Pacific side of Mexico and Indonesia. We hypothesize that individuals of Calappilia crossed the Central American Seaway prior to the closure of the Isthmus of Panama and they also migrated across the Tethys Sea. Miocene occurrences are known from Brazil, Chile, Australia, and New Zealand, suggesting dispersal well into the Southern Hemisphere by the Miocene. Quaternary occurrences have not been confirmed thus far.

Evolution of depositional systems and sedimentary cycles in Želiezovce Depression of the Danube Basin

Five deep wells (Pozba4, Pozba3, Dubnik1, Nova Vieska1, Modrany1), drilled in the Želiezovce depression of the south-east Danube Basin penetrate the Cenozoic sedimentary record in overall thickness ranging from 1000 m up to 3000 m, the total thickness gradually increases from South to the North. This area is well known for the complex geological structure related to the Central Western Carpathians and Transdanubian Range junction along the Hurbanovo – Diosjeno line. Many authors have studied this area in the past, nevertheless Depositional systems, sedimentary cycles and the development of sedimentary facies were never understood in detail. The Re-evaluation of biostratigraphy, paleoecology, sedimentology and the Re-interpretation of e-logs ware all incorporated into well correlations, what resulted in definition of four main sedimentary cycles: (1) The Lowermost Oligocene cycle, consisting of mudstones with occasional sandstone intercalations, associated with slope to offshore marine environment what is supported by the presence of the NP 22 calcareous nannoplankton zone. (2) The transgressive Langhian (Lower Badenian) deposits, composed of mudstones with epiclastic volcanic material and tuffite beds ware associated with shelfall to offshore environement the age is supported by the NN4 - NN5 calcareous nannoplankton zone. (3) The Serravallian (Upper Badenian - Sarmatian) cycle is composed mainly by mudstones with abundant Lithothamnium fragments associated with brackish coastal pain environment, supported by the NN6 calcareous nannoplankton zone and by the mass occurrence of fish scales and Ervilia dissita (Eichwald) bivalves. (4) The overlying strata are represent the Tortonian-Pliocene (Pannonian-Pliocene) cycle, consists mostly from claystone which are overlain by sandstone and siltstones layers is associated with lake, deltaic and alluvial plain environment.

Erosion and reworking of Pacific sediments near the Eocene‐Oligocene boundary

The Eocene‐Oligocene (E/O) boundary interval marks one of the largest and most rapid changes in climate during the last 50 Myr. Because of a very shallow calcium carbonate compensation depth in the Eocene, as well as the reworking of sediments and hiatuses in the boundary zone, it has also been one of the most difficult stratigraphic boundaries to study in deep water marine sections, especially in the Pacific Ocean. Recently, three drill sites have recovered complete sections of the E/O boundary interval in the tropical Pacific. A detailed study of these sections shows a series of pulses of reworked older radiolarians in the upper Eocene and lowermost Oligocene. The two largest pulses are coincident with the two sharp steps in carbon and oxygen isotope values that bracket the E/O boundary. Several smaller peaks in reworked material precede these two maxima. It is proposed that immixing of the older radiolarian species results from erosion and redeposition, possibly linked to pulses of new bottom water formation and the formation of a deep pycnocline.

Circum-Tethyan carbonate platform evolution during the Palaeogene: the Prebetic platform as a test for climatically controlled facies shifts

The distribution of selected shallow-benthic biota at circum-Tethyan carbonate platforms demonstrates an excellent proxy for the impact of latitudinally controlled cooling and variations in the trophic resources during the Palaeogene. In this study, we link and compare the spatial distribution and abundance of larger benthic foraminifera and hermatypic corals of Tethyan carbonate successions with new records from the Prebetic platform in SE Spain. The succession of the Prebetic platform is dominated by larger benthic foraminifera and coralline red algae throughout the Eocene, whereas corals were not recorded until the Late Eocene. Similar biotic trends were reported from 10 selected circum-Tethyan carbonate platforms. High-resolution carbon isotopes indicate a decoupling from the global carbon cycle during the latest Eocene and Early Oligocene. Thus, a possible scenario is demonstrated by the increasing restriction of the Prebetic shelf due to the continuing convergence of the Betic domain towards Iberia during the Early Oligocene. Based on previous studies, we refined earlier established Palaeogene platform stages, which reflect the evolution of shallow-benthic communities during the transition from global greenhouse to icehouse conditions. Global cooling led to the recovery of coral communities in the northern Tethyan realm during the Bartonian (stage IV). A prominent cooling event at the Bartonian-Priabonian boundary, associated with the demise of many symbiont-bearing larger foraminifera, caused the proliferation of coral reefs in the northern Tethys and the recovery of corals in the southern Tethys (stage V). The massive temperature drop related to the Oi-1 glaciation represented the base of platform stage VI (Early Oligocene-?). After a transient platform crisis during the lowermost Oligocene, coral reefs spread throughout the Tethys and proliferated with newly emerged larger benthic foraminifera.

EARLY OLIGOCENE RIPARIAN AND SWAMP FORESTS WITH A MASS OCCURRENCE OF ZINGIBEROIDEOPHYLLUM (EXTINCT ZINGIBERALES) FROM SAXONY, CENTRAL GERMANY

Abstract A remarkable fossil plant assemblage from the lowermost Oligocene Haselbach horizon (Grobers Member, Bohlen Formation) was excavated at the Vereinigtes Schleenhain opencast mine (northwestern Saxony, Germany) and is described herein. The lower unit of the Haselbach horizon represents abandoned channel deposits that contain masses of Zingiberoideophyllum liblarense leaves. Species identification of the leaves is based on morphological characters and micromorphological features of the cuticle. Other plant organs of the previously described whole plant Spirematospermum wetzleri-Zingiberoideophyllum liblarense, such as fruits, seeds, rhizomes, and rootlets, were also observed on associated bedding planes, which supports this whole-plant reconstruction. The other megafossil remains in this taphocoenosis, mostly leaves, are identified taxonomically and interpreted as being derived from a mixed softwood and hardwood riparian forest of Acer haselbachense, Apocynophyllum neriifolium, Carpinus grandis, Eng...

Middle Eocene to earliest Oligocene development in the eastern North Sea Basin: Biostratigraphy, magnetostratigraphy and palaeoenvironment of the Kysing-4 borehole, Denmark

The cored 154.5m deep Kysing-4 borehole in central Jutland is unique for high northern latitudes because it comprises an almost complete Middle Eocene to lowermost Oligocene succession mostly in a highly calcareous facies with abundant well preserved microfossils and from an upper bathyal environment. It has therefore been possible to carry out biostratigraphical analyses of calcareous nannofossils, benthic and planktonic foraminifera as well as dinoflagellate cysts. In order to correlate the section to the geomagnetic polarity time scale a detailed palaeomagnetic analysis has been performed. The magnetobiostratigraphic calibration allowed a well constrained identification of nearly all magnetochrons between Chron C21n and Chron C13n. The Eocene deposits consist mostly of calcareous ooze (Søvind Marl Formation with three new members formally defined), whereas the Oligocene Viborg Formation consists of moderately calcareous mud. Overall, the lithology of the deposits is in agreement with previous interpretations of a British provenance for the Eocene deposits and a Scandinavian provenance for the Oligocene deposits. Cyclic shifts in the clay/carbonate content during the Middle Eocene (chrons C19–C17) are attributed to orbitally controlled climate shifts. Obliquity seems to have been the dominating factor, but intervals dominated by precession end eccentricity signals also occur. A 10m thick hitherto unknown black mud (Moesgaard Member) of Scandinavian provenance and deposited very rapidly during the late Eocene Chron C16n.1n is interpreted as a precursor event to the Oligocene mode of sedimentation. Both the Moesgaard Member and the Lower Oligocene Viborg Formation are associated with sea-level falls.

Early Oligocene cooling reflected by the dinoflagellate cyst Svalbardella cooksoniae

The early Oligocene interval in several boreholes from the eastern North Sea and Denmark has been studied for dinoflagellate cysts. The cold water dinoflagellate cyst Svalbardella cooksoniae was recorded in a narrow lowermost Oligocene interval in all offshore sections. A critical evaluation of previous records of Svalbardella cooksoniae reveals that it is present in the same narrow interval of Chron 12r, close to the NP21/NP22 boundary in many high and mid latitude Northern Hemisphere sections, ranging from the Greenland Sea in the north to Italy in the south. The Svalbardella cooksoniae interval is closely associated with the LO of the dinoflagellate cyst Areosphaeridium diktyoplokum. The age of the Svalbardella cooksoniae event indicates that it is synchronous with the Oi1a oxygen isotope maximum of Pekar and Miller (1996) and Pekar et al. (2002). In the Danish land area the Svalbardella cooksoniae interval and hence the Oi1a event is shown to coincide with an unconformity. A regional comparison shows that synchronous unconformities are present also in Belgium and New Jersey. A slightly older regional unconformity occurring on both sides of the North Atlantic coincides with the Oi1 oxygen isotope maximum of Pekar and Miller (1996). The finding of a sedimentary package separated by two successive regional unconformities is interpreted to reflect a significant, temporary eustatic sea level rise, and hence a melting phase on the East Antarctic ice sheet between the Oi1 and Oi1a glacioeustatic sea level falls. The paleogeographic distribution and lower frequency of Svalbardella during the earliest Oligocene Oi1a event, as compared with the mid Oligocene Oi2b Svalbardella spp. event, suggest that the Oi1a glacial episode was less severe than the Oi2b glaciation. This is in agreement with recent ice volume estimates for the two events.

Eocene-Oligocene global climate and sea-level changes: St. Stephens Quarry, Alabama

We integrate upper Eocene–lower Oligocene lithostratigraphic, magnetostratigraphic, biostratigraphic, stable isotopic, benthic foraminiferal faunal, downhole log, and sequence stratigraphic studies from the Alabama St. Stephens Quarry (SSQ) core hole, linking global ice volume, sea level, and temperature changes through the greenhouse to icehouse transition of the Cenozoic. We show that the SSQ succession is dissected by hiatuses associated with sequence boundaries. Three previously reported sequence boundaries are well dated here: North Twistwood Creek–Cocoa (35.4–35.9 Ma), Mint Spring– Red Bluff (33.0 Ma), and Bucatunna-Chickasawhay (the mid-Oligocene fall, ca. 30.2 Ma). In addition, we document three previously undetected or controversial sequences: midPachuta (33.9–35.0 Ma), Shubuta-Bumpnose (lowermost Oligocene, ca. 33.6 Ma), and Byram-Glendon (30.5–31.7 Ma). An ~0.9‰ δ 18 O increase in the SSQ core hole is correlated to the global earliest Oligocene (Oi1) event using magnetobiostratigraphy; this increase is associated with the ShubutaBumpnose contact, an erosional surface, and a biofacies shift in the core hole, providing a fi rst-order correlation between ice growth and a sequence boundary that indicates a sea-level fall. The δ 18 O increase is associated with a eustatic fall of ~55 m, indicating that ~0.4‰ of the increase at Oi1 time was due to temperature. Maximum δ 18 O values of Oi1 occur above the sequence boundary, requiring that deposition resumed during the lowest eustatic lowstand. A precursor δ 18 O increase of 0.5‰ (33.8 Ma, mid-chron C13r) at SSQ correlates with a 0.5‰ increase in the deep Pacifi c Ocean; the lack of evidence for a sea-level change with the precursor suggests that this was primarily a cooling event, not an ice-volume event. Eocene–Oligocene shelf water temperatures of ~17–19 °C at SSQ are similar to modern values for 100 m water depth in this region. Our study establishes the relationships among ice volume, δ 18 O, and sequences: a latest Eocene cooling event was followed by an earliest Oligocene ice volume and cooling event that lowered sea level and formed a sequence boundary during the early stages of eustatic fall.

Shallow-marine ostracode faunas around the Eocene/Oligocene boundary in the northwestern Kyushu, southwestern Japan

Middle Eocene–early Oligocene ostracode faunal changes in northwestern Kyushu of southwestern Japan are identified in this study. Ostracodes occur from shelf deposits of five formations: the middle Eocene Okinoshima, the upper Eocene Funazu, the uppermost Eocene–lowermost Oligocene Kishima, the lowermost Oligocene Itanoura, and the lower Oligocene Waita Formations. The middle Eocene–earliest Oligocene ostracodes were characterized by warm-water genera, indicating tropical, subtropical and Tethyan genera, whereas the late early Oligocene ostracodes do not include warm-water taxa, consisting of temperate realm genera. The middle Eocene–earliest Oligocene ostracodes do not include remarkable changes of species composition, in contract with equatorial Pacific radiolarians and West Coast USA molluscs. Ostracodes suggest that distinct climatic cooling did not occur in the southwestern Japan during the middle Eocene–earliest Oligocene.

Dinoflagellate cysts from the Middle Eocene to ?lowermost Oligocene succession in the Kysing research borehole, central Danish basin

Rich and well‐preserved assemblages of organic walled dinoflagellate cysts in 50 samples from a 154 m thick and almost complete, Middle Eocene to ?lowermost Oligocene section from the Kysing Research Borehole in eastern Jylland, Denmark are systematically described. One genus Costacysta gen. nov., and twelve species Chiropteridium eocaenicum sp. nov., Costacysta bucina gen. et sp.nov., Distatodinium pilosum sp. nov., Echinidiniuml lucidum sp.nov., Hapsocysta kysingensis sp.nov., Horologinellal pentagonalis sp.nov., Operculodinium eisenackii sp. nov., Phthanoperidinium cornutum sp. nov., Selenopemphix septum sp. nov., Svalbardella partimtabulata sp. nov., Thalassiphora gracilis sp. nov. and Thalassiphora microperforata sp. nov. are formally described. The genus Hapsocysta is emended, and is considered to be a senior synonym of Piccoladinium. The gradual change of the dinoflagellate cyst assemblages in this section demonstrates that sedimentation was almost continuous during the time span of ca. 12 Ma. The biostratigraphic resolution based on dinoflagellate cyst events is generally finer than the calcareous nannofossil NP biozonation. A comparison with published dinoflagellate cyst data from the Norwegian‐Greenland Sea shows that several important events are mainly synchronous throughout the region, suggesting a general similarity of the water masses. An isolated occurrence of Svalbardella suggests a short cooling event during early Bartonian times. The palynofacies in most of the section is almost purely of pelagic type. A more proximal, mid shelf palynofacies and a distinctive episode of reworking coincide with the Upper Eocene Moesgaard Clay and indicate a brief, but rather large sea level fall during the deposition of this unit. The Eocene/Oligocene boundary is tentatively identified near the base of the Viborg Formation, and approximately coincides with increased reworking of dinoflagellate cysts and a strong increase in bisaccate pollen, indicating more proximal conditions and possibly also a climatic cooling.

DINOFLAGELLATE CYSTS FROM THE MIDDLE EOCENE TO ?LOWERMOST OLIGOCENE SUCCESSION IN THE KYSING RESEARCH BOREHOLE, CENTRAL DANISH BASIN

Abstract Rich and well-preserved assemblages of organic walled dinoflagellate cysts in 50 samples from a 154 m thick and almost complete, Middle Eocene to ?lowermost Oligocene section from the Kysing Research Borehole in eastern Jylland, Denmark are systematically described. One genus Costacysta gen. nov., and twelve species Chiropteridium eocaenicum sp. nov., Costacysta bucina gen. et sp. nov., Distatodinium pilosum sp. nov., Echinidinium? lucidum sp. nov., Hapsocysta kysingensis sp. nov., Horologinella? pentagonalis sp. nov., Operculodinium eisenackii sp. nov., Phthanoperidinium cornutum sp. nov., Selenopemphix septum sp. nov., Svalbardella partimtabulata sp. nov., Thalassiphora gracilis sp. nov. and Thalassiphora microperforata sp. nov. are formally described. The genus Hapsocysta is emended, and is considered to be a senior synonym of Piccoladinium. The gradual change of the dinoflagellate cyst assemblages in this section demonstrates that sedimentation was almost continuous during the time span of ca...

The Palaeogene flora of Hochstetten‐Dhaun (Nahe‐area, Rhineland‐Palatinate, SW‐Germany)

AbstractA flora from the Palaeogene of Hochstetten‐Dhaun (Nahe‐area, Rhineland‐Palatinate, SW‐Germany) is described. Leaf remains of the intermediate Fagaceae species Eotrigonobalanus furcinervis (Rossmaessler) Walther &amp; Kvaček represent the dominant element. Moreover, Equisetum sp., Tetraclinis salicornioides (Unger) Kvaček, Daphnogene cinnamomifolia (Brongniart) Unger forma lanceolata sensu Kvaček &amp; Walther, Daphnogene cinnamomifolia (Brongniart) Unger forma cinnamomifolia sensu Kvaček &amp; Walther, Daphnogene sp., cf. Quercus sp. vel Castaneophyllum sp., Eotrigonobalanus furcinervis (Rossmaessler) Walther &amp; Kvaček, cf. subsp. haselbachensis Kvaček &amp; Walther, cf. Trigonobalanopsis rhamnoides (Rossmaessler) Kvaček &amp; Walther, and Populus cf. germanica (Menzel) Walther occur in this flora. In addition, three leaf‐morphotypes are characterized and several undeterminable leaf remains are listed. We interpret the source vegetation as a mixed mesophytic forest. Based on the composition and overall morphological and physiognomical character, we conclude that the flora is of lowermost Oligocene age.

New constraints to the geodynamic evolution of the southern sector of the Calabria–Peloritani Arc (Italy)

Abstract New studies have been carried out on the Tertiary of the Stilo Unit, the uppermost of the Calabria–Peloritani Arc southern sector, and the Stilo–Capo d'Orlando Formation, sealing the whole nappe stack. The Tertiary terrains linked to the Mesozoic cover of the Stilo Unit consist of the lowermost Oligocene Palizzi Formation and the Late Rupelian–Aquitanian Pignolo Formation. The possibility that they deposited before the emplacement of this unit as the highest tectonic sheet of the sector is suggested. The base of the Stilo–Capo d'Orlando Formation resulted of Burdigalian age in both type areas. This interpretation, together with the existing and new data, allows proposing an age close to the Aquitanian–Burdigalian boundary for the stacking of the whole Calabria–Peloritani Arc southern sector. To cite this article: G. Bonardi et al., C. R. Geoscience 334 (2002) 423–430.