Magneto- and biostratigraphy of the Jurassic/Cretaceous boundary in the Lókút section (transdanubian range, Hungary)

Abstract

Jurassic-Cretaceous sediments of Transdanubian Range in NorthernHungary mostly retain their primary magnetizations and are suitable for detailed bio-and magnetostratigraphic studies. The Lókút section, 13 m in thickness, is localized in the central part of the Transdanubian Range. It contains the Jurassic/Cretaceous boundary in pelagic carbonate facies. Although the colour of the rocks changes from reddish-pinkish in the bottom to almost white at the top of the section, magnetite was identified as a magnetic carrier without evidence of hematite. Integrated bio-and magnetostratigraphical investigations resulted in construction of chronostratigraphical scheme. The section, embraces magnetozones from M21r to M18r, of upper Lower Tithonian (Parastomiosphaera malmica Zone) to Lower Berriasian age (Calpionella alpina Subzone). Sedimentation rate of pelagic limestones increased from 1−3 m/My during Tithonian to 5−7 m/My during Berriasian. The sedimentation rate and its changes up the section are comparable to those from the Jurassic/Cretaceous boundary sections of Trento plateau (Southern Alps, Italy) -sedimentary environments of Trento plateau and central Transdanubian Range in that time might be similar. Sedimentation rate within Umbrian Apennine basins and Križna unit in the Western Tatra Mts. seems significantly higher. Analysis of rock magnetic parameters reveals that detrital input was much lower into the Lókút section than into Križna basin in the Tatra Mts. (Zliechov trough). Increase of sedimentation rate occurs in both sections in the Upper Tithonian -Lower Berriasian. It coincides with the onset of calpionellid limestone facies and is related to increased productivity of calcareous micro-and nannoplankton. Detailed correlation of both sections basing on rock magnetic parameters and susceptibility changes is, however, not possible. They are dependent mostly on the local sedimentary conditions (Bakony Mts. -deep water plateau; Križna unit -deep water trough) and correlation with any "global" paleoenvironmental (climatic, eustatic) trends is not straightforward. J. Grabowski et al. 2 Stud. Geophys. Geod., 54 (2010) K e y w o r d s : Jurassic/Cretaceous boundary, magnetostratigraphy, calpionellids, Transdanubian Range, Hungary

Carbon cycle history through the Jurassic–Cretaceous boundary: A new global δ13C stack

“…Higher up-section, a return towards more positive values up to 0.7‰ is observed. iostratigraphic data (Vigh, 1984;Főzy et al, 2011;rabowski et al, 2010a) together with magnetostratigraphic data (Grabowski et al, 2010a) allow us to accurately place the low point seen in the carbon isotope curve within these schemes. This minimum appears in the upper part of …”

Magneto-, and isotope stratigraphy around the Jurassic/Cretaceous boundary in the Vysoká Unit (Malé Karpaty Mountains, Slovakia): correlations and tectonic implications

“…It should be noted that the magnetic susceptibility pattern across the J/K boundary is exactly opposite to that noted typically in the Tethyan sections. There is a general tendency of magnetic susceptibility decrease from the Upper Tithonian to Lower Berriasian strata; it is known from sections of Val Bosso (Houša et al 2004), Brodno (Houša et al 1996(Houša et al , 1999 Grabowski et al 2010). The opposite trend, observed in the Hlboča section only, is related to relative abundance of SP magnetite in the Padlá Voda Formation.…”

“…Microbiostratigraphic callibration of Late Tithonian/Berriasian magnetozones was successfully performed in south Tethyan sections of the Apennines and Southern Alps Ogg et al 1991). Detailed magnetostratigraphic studies in the Apennines, Tatra Mts and Transdanubian Mts were published recently (Houša et al 2004;Speranza et al 2005;Grabowski & Pszczółkowski 2006;Grabowski et al 2010) and pilot results were reported from the Eastern Alps (Pruner et al 2009). The Brodno section in the Pieniny Klippen Belt (PKB) is currently proposed as the J/K regional stratotype in the Carpathians ).…”

Hungarian national report on IAGA 2007–2010

“…Publications by Pálfy et al (2007) and Grabowski et al (2010) deal with geological correlation with the aid of palaeomagnetic polarity zones. Karátson et al (2007), Márton E (2007), Márton E et al (2007aMárton E et al ( , 2007b are concerned in correlation through the combination of palaeomagnetic marker horizons (which are the manifestations of dramatic changes in the orientation of the relevant tectonic unit) and polarity zones.…”