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

Abstract

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.

Growth oscillation in larger foraminifera

“…Larger benthic foraminifera (LBF) are large-sized shallow-water marine protists that host symbiotic microalgae, and whose tests (shells) have to function as glass houses to let light penetrate them (Hottinger 1982). Because of their high evolutionary rates, great diversity, and exceptional abundance in fossil and Recent oligotrophic tropic and warm temperate marine environments, LBF are routinely used in biostratigraphy (e.g., Serra-Kiel et al 1998; Egger et al 2013) and paleoenvironmental analyses (e.g., Beavington-Penney and Racey 2004, Gebhardt et al 2013).…”

Towards a Calibrated Larger Foraminifera Biostratigraphic Zonation: Celebrating 18 Years of the Application of Shallow Benthic Zones

“…During the eighteen years since the appearance of the SB zonation, a wealth of data on the morphology, biostratigraphy, and paleogeography of Paleogene LBF became available, leading to significant updates ( Fig. 1): (1) Increasing the precision in determining boundaries and achieving further subdivision of the previous standard zones as results of biometric studies on different nummulitid genera such as Heterostegina and Spiroclypeus (Less and Ozcan 2008) or through a multidisciplinary study of a section (Less et al 2011;Zakrevskaya et al 2011;Ozcan et al 2009Ozcan et al , 2014Ozcan et al , 2015; (2) Increasing knowledge of the characteristic foraminiferal assemblages in standard biozones, due to new studies on composition, ecology, and age attribution of regional faunas spanning from the Pyrenean Basin, to the Adriatic-Apulian area, Greece, Eastern Africa, Turkey, Oman, Pakistan, and Tibet (Benedetti et al 2010(Benedetti et al , 2011Pearson 2011, 2012;Zhang et al 2013;Accordi et al 2014;Cotton et al 2014Cotton et al , 2015Drobne et al 2014;Kahsnitz et al 2016); (3) New attempts at correlating the SB zones with isotope and magnetic stratigraphy and with the standard plankton zones (Rodriguez-Pintó 2012Gebhardt et al 2013;Egger et al 2013;Molina et al 2016); (4) New studies of foraminiferal assemblages from the Peritethys (Crimea, Northern Caucasus to Mangyschlak, Northern Peri-Aralian areas) and from the Caribbean region (Zakrevskaya 2011;Molina et al 2016); and (5) New detailed studies of the systematics and inner structures of particular LBF groups, such as rotaliids, larger miliolids, and ophtalmidids (Hottinger 2009(Hottinger , 2014Benedetti and Briguglio 2012;Benedetti 2015;Briguglio et al 2011Briguglio et al , 2013Briguglio et al , 2016.…”

Morphological variations in Cycloclypeus carpenteri: Multiple embryos and multiple equatorial layers

“…Changes in the internal structures of LBF have been successfully correlated to time, and most of the shallow water biozones are now calibrated using biometry on selected parameters in LBF (e.g., Less, 1987;Serra-Kiel et al, 1998;Egger et al, 2013).…”