A DETAILED SEQUENCE STRATIGRAPHIC AND MAGNETOSTRATIGRAPHIC INVESTIGATION OF THE EOCENE-OLIGOCENE TRANSITION ON THE ISLE OF WIGHT, UK

The integrated sequence and magnetostratigraphic cross correlation of six continuous sections in Bouldnor Cliff (Western Isle of Wight) produced a high resolution Early Oligocene magnetic polarity stratigraphy. A composite magnetic polarity sequence from sections defines a continuous sequence from Chron C13r to C12r, from 33.6 to 33.17 Ma (Early Oligocene). In addition, a short reverse polarity event that correlates to the cryptochron in the GPTS is observed (i.e. in C13n). Sequences (transgressive-regressive cycle and confined unconformities) are well identified in Bouldnor Cliff sections marking the sedimentary hiatus as FSST. Observed system tracts (LST, TST) suggest freshwater-estuarine-freshwater environment at Boudnor cliff section during Early Oligocene period. Sedimentary hiatus in between the log bed and the Nematura Bed is therefore correlated to the sea level fall due to Oi-1 glaciation event. The resulting sequence-magnetostratigraphic framework now established enables to correlate the Oi-1 event and the Grande Coupure to the sedimentary hiatus below the Nematura Bed and follows the re-defined magnetochrons as proposed by Hooker et al., (2009). Improved calibration to GPTS further recognizes the location of Eocene-Oligocene boundary within the upper half of Bembridge Marl Member as interpreted by Hooker et al., (2009).Faculty of Science and Technolog