New bio-magnetostratigraphic data on the Miocene Moria section (Northern Apennines, Italy): connections between the Mediterranean region and the North Atlantic Ocean

Abstract

New bio-magnetostratigraphic data have been acquired from the Burdigalian part of the Moria section in the Umbria–Marche Apennine (Central Italy). The investigated sedimentary sequence is 55 meters thick and comprises the transition between the Bisciaro and the Schlier formations (Auctorum), composed of five meters of indurated marly limestones, followed by about 40 meters of blue marly clays capped by 10m of alternating clays and calcareous layers. According to existing literature, the sequence contains the so-called “Piero della Francesca Level” (Auctorum), a few-centimeters-thick biotite-rich level. The sequence has been sampled for paleomagnetic and calcareous plankton analyses. Four magnetic polarity zones have been documented in the middle and upper part of the section. The calcareous plankton content shows different degrees of preservation, from poor to good for calcareous nannofossils and poor to medium for planktonic foramini- fers. Several useful biohorizons have been observed and chronologically constrained through calibration to the magnetostratigraphic data. The studied section ranges from the top of Chron C5Dr.1n to Chron C5Cn.2r, covering the time interval from 17.7 to 16.4Ma (according to the ATNTS04) almost continuously, with a small hiatus of at least 34ka at the C5Dn/C5Cr transition. The integration of our results with those from previous studies of the same section and comparisons with data from other Mediterranean and North Atlantic sequences allows to evaluate the synchrony of the observed biohorizons with other parts of the Mediterranean and the Atlantic Ocean during a still relatively poorly known time interval.