HR: 0800h
AN: T11C-0731    [Abstracts]
TI: Ready to Detach: new insight into the geodynamics of northern Apennines.
AU: * Levin, V
EM: vlevin@rci.rutgers.edu
AF: Rutgers University, Dept. of Geological Sciences, Piscataway, NJ 08854, United States
AU: Park, J
EM: jeffrey.park@yale.edu
AF: Yale University, Dept. of Geology and Geophysics, New Haven, CT 06520, United States
AU: Lucente, F P
EM: lucente@ingv.it
AF: INGV, Via Vigna Murata 605, Rome, 00143, Italy
AU: Margheriti, L
EM: margheriti@ingv.it
AF: INGV, Via Vigna Murata 605, Rome, 00143, Italy
AU: Pondrelli, S
EM: pondrelli@bo.ingv.it
AF: INGV, Via Donato Creti 12, Bologna, 40128, Italy
AU: Salimbeni, S
EM: salimbeni@bo.ingv.it
AF: INGV, Via Donato Creti 12, Bologna, 40128, Italy
AB: Due to their near-alignment with the relative plate motion between African and Eurasian plates, the Apennines mountain range requires a local geodynamic mechanism. A subduction zone retreat scenario is often invoked, with the lithosphere under the Adriatic sea descending beneath the lithosphere of the Tyrrhenian sea. Many surface expressions of a retreating subduction zone are found in the Apennines, such as the seismic expression of a lithospheric slab at depth, juxtaposed belts of compression and extension in the crust, a difference in crustal thickness consistent with thinning the overriding plate, and evidence for lateral translation of the orogen over time. In northern Apennines the lack of active volcanism and deep seismicity suggest an interruption of the subduction process, or else encourage models of lithospheric removal that leave the upper crust in place. New seismological observations obtained in the northern part of the Apennines also encourage scenarios independent of steady-state subduction. The indicators of upper mantle deformation derived from two different seismological techniques (shear-wave splitting and surface-wave mode conversion) suggest a pattern of upper mantle deformation that differs in significant ways from that predicted by the subduction zone retreat scenario. We compare the inferred mantle flow pattern with tomographic images, trench position reconstructions and deep crustal seismicity, and argue for the incipient-detachment scenario in northern part of the Apennines. Specifically, we propose that upper mantle flow on the western side of northern Apennines (beneath the Tyrrhenian Sea) likely responds to the retreat of the Adriatic subduction zone further south, while deformation on the eastern side is better explained by an incipient detachment of the Adriatic mantle lithosphere.
UR: http://earth.geology.yale.edu/RETREAT/
DE: 1213 Earth's interior: dynamics (1507, 7207, 7208, 8115, 8120)
DE: 1236 Rheology of the lithosphere and mantle (7218, 8160)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting