Magnetostratigraphy of the Kyparissia and Choremi stratigraphic sequences (Megalopolis basin): Preliminary results

Abstract

During the 2020 research campaign of the Megalopolis Palaeoenvironmental Project, 8 oriented core samples were collected for paleomagnetism from the archeological site of KYP4. In 2021, a more extensive paleomagnetic sampling campaign was conducted across the 22 m-thick Kyparissia-4 and 28 m-thick Choremi-6 sections, located stratigraphically the former above the latter in the Kyparissia and Choremi mines, respectively (Fig. 1). Each stratigraphic section was subdivided into different sub-sections (8 subsections for Kyparissia-4 and 6 subsections for Choremi-6), in order to cover the stratigraphy homogeneously. We sampled every 20-30 cm collecting a total of 103 oriented core samples (69 at Kyparissia-4 and 34 at Choremi-6). Cores were then cut into standard-sized ~10cc cylinders to perform different magnetostratigraphic and rock-magnetic analyses from the same stratigraphic level. The primary objective was to determine the geomagnetic polarity recorded in the sediments and perform correlations at the basin scale using primarily the Brunhes-Matuyama boundary dated to 0.773 Ma (Channell et al., 2020), which represents the most recent reversal of the Earth’s magnetic field. We also aimed at identifying short reversals that could potentially improve the magnetochronology of these sections.