Tectonic controls on the genesis of ignimbrites from the Campanian Volcanic Zone, southern Italy

Abstract

¶The Campanian Plain is an 80 × 30 km region of southern Italy, bordered by the Apennine Chain, that has experienced subsidence during the Quaternary. This region, volcanologically active in the last 600 ka, has been identified as the Campanian Volcanic Zone (CVZ). The products of three periods of trachytic ignimbrite volcanism (289–246 ka, 157 ka and 106 ka) have been identified in the Apennine area in the last 300 ka. These deposits probably represent distal ash flow units of ignimbrite eruptions which occurred throughout the CVZ. The resulting deposits are interstratified with marine sediments indicating that periods of repeated volcano-tectonic emergence and subsidence may have occurred in the past. The eruption, defined as the Campanian Ignimbrite (CI), with the largest volume (310 km3), occurred in the CVZ 39 ka ago. The products of the CI eruption consist of two units (unit-1 and unit-2) formed from a single compositionally zoned magma body. Slightly different in composition, three trachytic melts constitute the two units. Unit-1 type A is an acid trachyte, type B is a trachyte and type C of unit-2 is a mafic trachyte.