The Taverna San Felice Dike (NE of Roccamonfina Volcano): Unraveling Magmatic Intrusion Processes and Volcano‐Tectonics in the Tyrrhenian Margin of the Southern Apennines

Abstract

The Roccamonfina volcano is located within the Garigliano Graben (southern Apennines, Italy) and has been active throughout the Middle-Late Pleistocene. Along its polyphase volcanic history (630–55 ka), including several caldera-forming eruptions (385–230 ka), several effusive/mildly explosive monogenetic events occurred along the volcano slopes, within the summit caldera, and along the graben-bounding carbonate reliefs. In this paper, we present a multidisciplinary study of a mafic magmatic feeder dike intruded within the Meso-Tertiary carbonates and overlying Lower Pleistocene breccias of Mt Cesima, northeast of the Roccamonfina volcano. We performed a stratigraphic and structural survey of the area and petrographic analyses on several samples of the dike. Results indicate that a ∼1 km long fissure fed an eruption that also emplaced a Strombolian pyroclastic sequence. Petrological data show that an open-system mafic recharge fueled the tephritic magma that fed the eruption, whereas no evidence of significant pre/syn-eruptive assimilation of carbonate has been identified. Stratigraphic and petrological data do not allow to firmly constrain the timing of the eruption, which could belong both to the pre-Brown Leucitic Tuff (>354 ka) and to the post-White Trachytic Tuffs (<230 ka) epochs of activity of the Roccamonfina volcano. Structural data show that the dike is broadly oriented E-W and changes direction toward NE-SW in correspondence with a pre-existing fault damage zone. We suggest that magma was intruded during an N-S trending extensional event in the Middle Pleistocene, whose prolonged activity resulted in regional uplift and exhumation of regional significance.