HR: 10:20h
AN: T52B-01 INVITED     [Abstracts]
TI: Subduction and Mantle Convection in the Western Mediterranean
AU: * Faccenna, C
EM: faccenna@uniroma3.it
AF: Dip. Scienze Geologiche, Univ."Roma TRE", L.go S.L. Murialdo 1, Roma, 00146 Italy
AU: Piromallo, C
EM: piromallo@ingv.it
AF: Istituto Nazionele di Geofisica e Vulcanologia, Via di Vigna Murata 605, Roma, 00143 Italy
AU: Civetta, L
EM: civetta@ov.ingv.it
AF: Osservatorio Vesuviano, Via Diocleziano, 328, Napoli, 80124 Italy
AU: D'Antonio, M
EM: masdanto@unina.it
AF: Dip. Scienze della Terra, Univ Federico II, L.go S.Marcellino 10, Napoli, 80138 Italy
AU: Margheriti, L
EM: margheriti@ingv.it
AF: Istituto Nazionele di Geofisica e Vulcanologia, Via di Vigna Murata 605, Roma, 00143 Italy
AU: Funiciello, F
EM: ffunicie@uniroma3.it
AF: Dip. Scienze Geologiche, Univ."Roma TRE", L.go S.L. Murialdo 1, Roma, 00146 Italy
AU: Rossetti, F
EM: rossetti@uniroma3.it
AF: Dip. Scienze Geologiche, Univ."Roma TRE", L.go S.L. Murialdo 1, Roma, 00146 Italy
AB: The western Mediterranean subduction zone (WMSz) extends from the northern Apennine to southern Spain and turns around forming the narrow and tight Calabrian and Gibraltar Arcs. The evolution of the WMSz is characterised by a first phase of orogenic wedging followed, from 30 Ma on, by trench retreat and back-arc extension. Combining geological data, tomographic images of the western Mediterranean mantle, plate kinematics, geochemical data and laboratory modelling, we describe the evolution of the WMSz during the last 35 Ma. Our reconstruction shows that the two arcs form by fragmentation of the 1500 km long WMSz in small, narrow slabs. Once formed, these two narrow slabs retreat outward, producing back-arc extension and large-scale rotation of the flanks, shaping the arcs. The Gibraltar arc first formed during the middle Miocene, while the Calabrian arc formed later, during the Late Miocene-Pliocene. Despite the different paleogeographic settings, the mechanism of rupture and backward migration of the narrow slabs presents similarities on both sides of the western Mediterranean, suggesting that the slab deformation is also driven by lateral mantle flow that is particularly efficient when slabs show a retrograde motion in a restricted (upper mantle) style of mantle convection. In particular we present evidences on the presence of lateral mantle flow around the edge of the Calabrian slab and reconstruct its path during the last 10 Ma. This has been unravel using present-day seismological constraints on the geometry of the slab (tomographic images) and on the path of mantle anisotropy, coupled with tectonic reconstruction and geochemical signature of volcanic rocks.
DE: 8180 Tomography
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8155 Plate motions--general
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting