INTEGRATED STRATIGRAPHY OF THE UPPER PALEOCENE – EOCENE STRATA OF MARAMBIO (SEYMOUR) ISLAND, ANTARCTIC PENINSULA

MONTES, M; NOZAL, F; SANTILLANA, S; TORTOSA, F; BEAMUD, E; MARENSSI, S

Buenos Aires

Conferencia; SCAR Open Science Conference; 2010

SCAR

We present an integrated chart showing our most up to date stratigraphic knowledgeof the Upper Paleocene-Eocene strata cropping out on Marambio Island. It includes previouslitho, bio-and chemo-stratigraphic information and original (preliminary) magnetostratigraphy,results. The lithostratigraphy corresponds to that presented on the new Marambio Islandgeological map (Marenssi et al., 2008; Montes et al., in press). Biostratigraphic data arebased on palynomorphs (Askin, 1997), dinoflagellates and other groups of microfossils(Harwood, 1988, Wrenn and Hart, 1988) and vertebrates (Bond et al., 1993,Reguero et al.,2002). The chemostratigraphic data allowing to assign absolute ages is mainly based on87Sr/86Sr isotopic determinations on invertebrate shells (Dingle and Lavelle, 1998, Dutton etal., 2002; Marenssi, 2006, Ivany et al., 2008). Magnetostratigraphic data is original and wasobtained based on a preliminary sampling during the completion of the new geological map.A curve representing the variations in the sedimentation rate (meters/Ma) was obtainedplotting the uncompacted thicknesses of the Cross Valley-Wiman and La MesetaFormations against the chronoestratigraphic scale of Granstein et al., (2004) (GTS' 04). Byextrapolating the boundaries of the stratigraphic units we have derived their possibleabsolute ages. When including the eustatic curves of Miller et al., (2005) and Haq, et al.,(1987) the chart shows that the main erosive surfaces may correspond to important hiatusesconsistent with lowstands in the sea-level.