Biota, palaeoenvironments and biostratigraphy of continental Oligocene deposits of the South German Molasse Basin (Penzberg Syncline) (original) (raw)
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International Journal of Earth Sciences, 2008
A detailed integrated stratigraphic study was carried out on middle Miocene fluvial successions of the Upper Freshwater Molasse (OSM) from the North Alpine Foreland Basin, in eastern Bavaria, Germany. The biostratigraphic investigations yielded six new localities thereby refining the OSM biostratigraphy for units C to E (sensu; Heissig, Actes du Congres BiochroM’97. Mem Trav EPHE, Inst Montpellier 21, 1997) and further improving biostratigraphic correlations between the different sections throughout eastern Bavaria. Radioisotopic ages of 14.55 ± 0.19 and 14.88 ± 0.11 Ma have been obtained for glass shards from the main bentonite horizon and the Ries impactite: two important stratigraphic marker beds used for confirming our magnetostratigraphic calibration to the Astronomical Tuned Neogene Time Scale (ATNTS04; Lourens et al. in Geologic Time Scale 2004, Cambridge University Press, 2004). Paleomagnetic analysis was performed using alternating field (AF) and thermal (TH) demagnetization methods. The AF method revealed both normal and reverse polarities but proofs to yield unreliable ChRM directions for the Puttenhausen section. Using the biostratigraphic information and radioisotopic ages, the magnetostratigraphic records of the different sections are tentatively correlated to the Astronomical Tuned Neogene Time Scale (ATNTS04; Lourens et al. in Geologic Time Scale 2004, Cambridge University Press, 2004). This correlation implies that the main bentonite horizon coincides to chron C5ADn, which is corroborated by its radioisotopic age of 14.55 Ma, whereas the new fossil locality Furth 460, belonging to OSM unit E, probably correlates to chron C5Bn.1r. The latter correlation agrees well with the Swiss Molasse locality Frohberg. Correlations of the older sections are not straightforward. The Brock horizon, which comprises limestone ejecta from the Ries impact, possibly correlates to C5ADr (14.581–14.784 Ma), implying that, although within error, the radioisotopic age of 14.88 ± 0.11 Ma is somewhat too old. The fossil localities in Puttenhausen, belonging to the older part of OSM unit C, probably coincide with chron C5Cn.2n or older, which is older than the correlations established for the Swiss Molasse.
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2010
The geology of the lower Miocene Upper Marine Molasse (OMM) of the North Alpine Foreland Basin (Molasse Basin) has been studied intensively. However, one problem that remains concerns the different informal names that have been assigned to the OMM units by local workers. Moreover, there is still no general consensus with regard to the precise lithostratigraphic content of these units. In this study, three outcrops in the Lake Constance area (SW Germany) displaying OMM sediments are investigated with regard to lithofacies, sedimentology and microfossils (benthic foraminiferal assemblages). The Kalkofen Formation is introduced as a formal lithostratigraphic name for the so-called Sandschiefer, which represents a mud-dominated succession of an inner to middle neritic environment. The overlying newly defi ned Baltringen Formation includes the former Bodmansande or Baltringer Schichten, which are sand-dominated deposits indicating a subtidal environment with strong tidal currents. The lower boundary of the Baltringen Fm is marked by a basal erosion surface and a pebbly basal layer (Baltringer Horizont). The Steinhöfe Formation is introduced as a formal lithostratigraphic term for the so-called Deckschichten or Feinsandserie. It overlies the Baltringen Fm and is marked by an unconformity at base. The Steinhöfe Fm comprises fi ner-grained sand/silt alternations indicative of a less high-energetic but still tidally infl uenced marginal marine setting. The abrupt shift between the mud-dominated Kalkofen Fm and sand-dominated Baltringen Fm is a result of the wellknown shallowing-upward event that separates the two classical OMM sedimentation cycles (sensu Lemcke et al. 1953). The unconformity at base of the Steinhöfe Fm adds support to the hypothesis of a third sedimentation cycle. Kurzfassung: Die Geologie der untermiozänen Oberen Meeresmolasse (OMM) im nordalpinen Vorlandbecken (Molassebecken) ist grundsätzlich gut bekannt. Allerdings gibt es für den süddeutschen Anteil des Molassebeckens noch keine lithostratigrafi sche Gliederung der OMM. Stattdessen existieren eine Reihe von informellen Schichtnamen für lokale oder regionale Faziesentwicklungen, deren stratigrafi scher Inhalt nicht immer einheitlich gehandhabt wird. In der hier vorliegenden Arbeit werden drei OMM-Aufschlüsse im Gebiet des Bodensees (SW-Deutschland) hinsichtlich ihrer Lithofazies, Sedimentologie und Mikrofossilien (benthonische Foraminiferen) vorgestellt. Die Kalkofen-Formation wird als lithostratigrafi scher Name für die bisher als Sandschiefer bezeichneten Schichten eingeführt; sie repräsentiert eine überwiegend tonigsiltige Abfolge des inneren bis mittleren Neritikums. Die darüber folgende neu defi nierte Baltringen-Formation umfasst die früher als Bodmansande oder Baltringer Schichten bezeichneten Sedimente; es handelt sich um Sand-dominierte Ablagerungen des subtidalen Bereichs mit starken Gezeitenströmungen. Die Untergrenze der Baltringen-Formation ist durch eine Erosionsdiskordanz und eine basale Gerölllage (Baltringer Horizont) charakterisiert. Für die über der Baltringen-Formation folgenden feinkörnigeren Sedimente, die bisher als Deckschichten oder Feinsandserie bezeichnet wurden, wird der Name Steinhöfe-Formation eingeführt. Die Steinhöfe-Formation zeigt an ihrer Basis ebenfalls eine Diskordanz. Sie besteht überwiegend aus Feinsand/Silt-Wechsellagerungen, die in einem weniger hochenergetischen, aber immer noch Gezeiten-beeinfl ussten Milieu abgelagert wurden. Der sehr deutliche Wechsel zwischen der Ton-Silt-dominierten Kalkofen-Formation und der Sand-dominierten Baltringen-Formation belegt die schon von Lemcke et al. (1953) festgestellte Verfl achung des Beckens, die zur Untergliederung der OMM in zwei Sedimentationszyklen geführt hat. Die Diskordanz an der Basis der Steinhöfe-Formation unterstützt die Annahme eines dritten OMM-Sedimentationszyklus.
E&G Quaternary Science Journal
The age of the push moraine complex Wallsbüll-Böxlund, Schleswig-Holstein, is unclear despite investigations in this area for decades. To address the timing of formation of both the push moraine complex and the peat and soils found in its depressions, an outcrop in Osterbylund (OBL) was investigated. Optically stimulated luminescence and 230 Th/U dating, as well as pollen analyses, were undertaken with the aim to correlate the soils OBL 1 to OBL 4 to interglacials and interstadials. The chronological studies were accompanied by detailed sedimentological investigations. The results of the pollen analyses put the peat unambiguously to the Eemian; the peat is equivalent to OBL 1. The overlying sands and the other intercalated soils are to be placed into the early Weichselian. While for OBL 2 the assignment to the Brörup interstadial is clear, it is more difficult to clearly correlate OBL 3 and OBL 4 to an interstadial due to poor luminescence signal resetting of the sands, especially above OBL 4. Considering all data available, it is most likely that OBL 3 formed during the Odderade interstadial and OBL 4 during the Keller interstadial. From the Eemian to early Weichselian ages of the peat and soils it is evident that the push moraine complex is of Saalian age; a Weichselian ice margin further in the west, as assumed in other studies, can therefore be excluded. Kurzfassung: Die Altersstellung des Stauchmoränenkomplexes Wallsbüll-Böxlund in Schleswig-Holstein ist trotz jahrzehntelanger Untersuchungen noch ungeklärt. Die in einem Aufschluss in Osterbylund (OBL) aufgeschlossenen Sedimente und Torfe sowie Böden wurden zur Klärung dieser Frage und auch zur Korrelation der Böden OBL 1 bis OBL 4 mit den bekannten Interglazialen und Interstadialen mittels optisch stimulierter Lumineszenz und Uran-Thorium sowie Pollenanalysen datiert. Detaillierte Published by Copernicus Publications on behalf of the Deutsche Quartärvereinigung (DEUQUA) e.V. 58 C. Thiel et al.: Chronological and sedimentological investigations sedimentologische Aufnahmen ergänzten die chronologischen Arbeiten. Die Pollenanalysen ordnen den in Depressionen vorkommenden Torf dem Eem zu; der Torf ist mit OBL 1 gleichzusetzen. Die aufliegenden Sande und die übrigen eingeschalteten Böden können alle in das Frühweichsel gestellt werden. Während für OBL 2 die Stellung in das Brörup-Interstadial aufgrund der Daten belegbar ist, gestalten sich die Zuordnungen für OBL 3 und OBL 4 etwas schwieriger, da schlechte Bleichung der Lumineszenzsignale der Sande insbesondere oberhalb von OBL 4 Unsicherheiten mit sich bringen. Unter Berücksichtigung der Gesamtheit der Daten ist eine Korrelation von OBL 3 mit dem Odderade-Interstadial und von OBL 4 mit dem Keller-Interstadial am wahrscheinlichsten. Aus diesen Daten ergibt sich zudem eine saalezeitliche Entstehung des Stauchmoränenwalls; ein, wie in anderen Studien angenommen, weichselzeitlicher Eisrand noch weiter westlich als der hier untersuchte Standort kann somit ausgeschlossen werden.
of the Early to Middle Miocene Upper Freshwater Molasse in eastern Bavaria (Germany)
2000
A detailed integrated stratigraphic study was carried out on middle Miocene fluvial successions of the Upper Freshwater Molasse (OSM) from the North Alpine Foreland Basin, in eastern Bavaria, Germany. The biostratigraphic investigations yielded six new localities thereby refining the OSM biostra-the older part of OSM unit C, probably coincide with chron C5Cn.2n or older, which is older than the correlations established for the Swiss Molasse.
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 2009
Evidence for tidal influences in the Upper Marine Molasse (OMM) of the Allgäu area (Southwest German part of the Molasse Basin) is presented. The studied sections in the "Ellhofer Tobel" ravine reveal an approximately 140 m thick succession of marine sediments. Four different facies types are distinguished in this succession: 1) a Glauconitic Sandstone Facies, 2) a Heterolithic Facies, 3) a Cross-Stratified Sandstone Facies and 4) a Conglomeratic Facies. These lithofacies represent different near coastal and shallow marine environments. A tidal influence is indicated by the presence of the Heterolithic Facies which contains associated epsilon cross-stratification and megaripples (or subaquatic dunes). A general current direction from south to north is consistent documented by subaquatic dune foresets and the orientation of ripple foresets. If the coastal environment near the southern coast of the Molasse Sea had a rather simple tidal current regime this dominant northerly current direction could be interpreted as ebb currents.
2015
The present work is a taxonomical study of the continental mollusks collected in several fossil outcrops in the districts of Biberach and Ravensburg (SE Baden-Württemberg state) and Neu-Ulm (SW Bavaria state), Germany, by one of the authors (V.J.S.) in the years 1983-2013. All these fossil sites are of Middle Miocene age (European Mammal Neogene zones MN 5 and MN 6) and belong to the Upper Freshwater Molasse (“Obere Süßwassermolasse” or OSM), in the North Alpine Foreland Basin of southern Germany. The molluscan fauna of these sites counts with 17 gastropod and three bivalve species: Tinnyea laureae, Pomatias sp., Bithynia sp., Theodoxus sp., Galba cf. G. dupuyiana, Lymnaea dilatata, Gyraulus applanatus, Planorbarius cornu, Opeas minutum, Clausiliidae indet., Triptychia sp., Archaeozonites costatus, Klikia sp., Pseudochloritis incrassata, Palaeotachea renevieri, Megalotachea silvana, Deroceras sp., Margaritifera fl abellata, Unio kirchbergensis and Sphaerium aff. S. rivicola. Finally, a few paleoenvironmental remarks are offered.
Austrian Journal of Earth Sciences, 2018
A detailed study of OMV wells throughout the Lower Austrian Molasse Basin demonstrates the existence of a distinct and synchronous upper Ottnangian (lower Miocene) stratigraphic signal, the Calcite Minimum Interval (CMI). It corresponds to the depositional phase of the Rzehakia Lake System. This signal is interpreted to be of chronostratigraphic importance as an expression of palaeoclimate and related sea-level change. It is represented by the brackish Traisen Formation, which crops out south of the Danube. The Traisen Formation correlates with sands and shales in OMV wells to the north, termed Wildendürnbach Formation. However, the CMI underlies a marine unit, the so-called “Oncophora Beds” (also known as Rzehakia Beds) as reported from OMV wells in the north at the border to the Czech Republic. We demonstrate that these former “Oncophora Beds” are younger, i.e. of Karpatian age, than originally assumed. Therefore, these deposits cannot be correlated to the late Ottnangian Traisen ...
Palaeontologische Zeitschrift, 2009
The continental mollusc fauna of Sandelzhausen (Southern Germany, Early/Middle Miocene, MN5) is presented and shown to consist of 66 snail and 3 bivalve taxa. Previous ecological interpretations were partly based on poorly preserved material and are shown to be erroneous. Within a series of quantitative samples, ecologically four mollusc communities can be distinguished (two each for terrestrial and freshwater molluscs), highly indicative of ecological conditions and changes in the landscape surrounding the fossil site as well as the locality itself. Open scrub-lands with temporary waters, as indicated by forms such as Granaria and the dominance of lymnaeids, are steadily replaced with damp forests with abundant litter and rotting wood surrounding a perennial lake with small tributaries. These more favorable conditions are indicated by an overall increase of mollusc diversity, rising abundance of planorbids, and presence of restricted forms such as Drepanotrema (intolerant to droughts) as well as certain forest dwellers such as Gastrocopta and hygromiids. Molluscs are highly sensitive to environmental changes, which is reflected in the fossil record of Sandelzhausen.