The Tyrrhenian transgression in the Tarquinia area (Northern Latium, Italy)

Abstract

Between the rivers Marta and Mignone, approximately 70 km North of Rome, the presence of Tyrrhenian sediments containing Strombus bubonius and Conus testudinarius has been known for a long time. Due to swift lateral facies variations, poor exposures and intervening tectonic uplift, coastline identification has not however been straightforward. Careful examination of morphologic features as well as of all the sections available in the area has led the authors to correlate the calcarenites of the distal area with the sands and gravels outcropping in the proximal area, directly fed by streams down the steep slopes. The coastline of maximum Tyrrhenian transgression was located from morphologic evidences between 40 and 45 meters. Just South of the River Mignone, the Tyrrhenian coastline had been previously identified at approximately the same altitude. North of the River Marta the coastline of the same age is instead found as low as 25 m a.s.l. and, farther North, at about 15 m. The differential uplift thus evidenced is consistent with the middle Pleistocene Tectonics in the same area.