Paper No. 378-4
Presentation Time: 9:00 AM-6:30 PM
REASSESSING THE BARTONIAN UNIT STRATOTYPES: AN INTEGRATED APPROACH
COTTON, Laura J., Department of Geological Sciences and Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, RIVERO-CUESTA, Lucía, Departamento de Ciencias de la Tierra, Universidad de Zaragoza, Pedro Cerbuna 12, Zaragoza, 50009, Spain, FRANCESCHETTI, Gloria, Dipartimento di Scienze della Terra, Universit. di Firenze, Via LaPira 4, Firenze, I 50121, Italy, IAKOVLEVA, Alina, Laboratory of Paleofloristics, Geological Institute, Russian Academy of Sciences, Pyzhevsky pereulok 7, Moscow, 119017, Russian Federation, HOOKER, Jerry J., Palaeontology Department, Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom, ALEGRET, Laia, Dept. Ciencias de la Tierra & IUCA, University of Zaragoza, Zaragoza, 50009, Spain, DINARÈS-TURELL, Jaume, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via di Vigna Murata 605, Roma, I-00143, Italy, YAGER, Stacy L., Dept. of Geological Studies, Ball State University, Muncie, IN 47306, FLUEGEMAN, Richard H., Dept. of Geological Sciences, Ball State University, Muncie, IN 47306-0475 and MONECHI, Simonetta, Dipartimento di Scienze della Terra, Universita degli Studi Firenze, Via La Pira 4, Firenze, 50121, Italy, lcotton@flmnh.ufl.edu
The Global boundary Stratotype Section and Point (GSSP) for the base of the Bartonian, currently remains undefined. The Bartonian unit stratotype is located at the Barton coastal section in the Hampshire Basin, on the South Coast of the UK. However the bases of the chronostratigraphic and lithostratigraphic units do not coincide. The parastratotype section is located at Alum Bay, 7 km away, on the Isle of Wight. Despite a number of studies carried out in 1970s and ‘80s on both sections, global correlation remains problematic.
The base of the Bartonian Stage in the type area is defined by the Nummulites prestwichianus bed, which provides a locally distinctive level, however is not widely correlatable outside of the Hampshire basin. Only a single, long-ranged, planktonic foraminifera has been identified, Dipsidripella danvillensis, and so correlation of this bed with planktonic foraminiferal biostratigraphy has not been possible. The dinoflagellates do show a taxonomic turnover with Rhombodinium draco occurring a few centemeters above the level of the N. prestwichianus bed at several localities in the Hampshire basin, however, this is not consistant outside of this region. Calcareous nannofossils from the site were relatively impoverished, with NP zones being largely recognized by secondary markers. However, Aubry (1983, 1986) recognized Reticulofenestra umbilica, which is a primary marker within the CP zonation, and suggests further correlation potential for calcareous nannoplankton. Palaeomagnetic studies have also been carried out at the Alum bay section; Dawber et al., (2011) identified C18n with the NP16-17 boundary and the Nummulites prestwichianus bed as being within the underlying reversed interval, but there are problems with their interpretation with the nannofossil record.Improvement in the stratigraphy is essential to better define this interval and provide a globally useful datum. In order to resolve this issue, we present a new assessment of the Alum Bay section using integrated smaller and larger benthic foraminiferal, dinoflagellate and nannofossil stratigraphy.
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