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How deep can we find the traces of Alpine subduction?
Author(s) -
Piromallo Claudia,
Faccenna Claudio
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl019288
Subject(s) - geology , subduction , slab , seismology , trench , lithosphere , mantle (geology) , discontinuity (linguistics) , slab window , transition zone , seismic tomography , tomography , geophysics , tectonics , oceanic crust , mathematical analysis , chemistry , mathematics , organic chemistry , layer (electronics) , physics , optics
Slab‐like seismic velocity heterogeneities below the Alpine chain, interpreted as subducted lithosphere, are imaged by tomographic studies down to only about 300 km depth. A non‐negligible discrepancy therefore exists between tomographic and geological data, the latter indicating at least 500 km of Tertiary convergence at trench. Yet a recently published tomographic study detects a pronounced high velocity anomaly at the bottom of the upper mantle right below the Alpine area. Combining tomographic images of the mantle, geological findings and plate system kinematics, we investigate how the presence of this feature in the transition zone below the Alps can be traced back to the Tertiary Alpine subduction and possibly explain the observed discrepancy. We propose that a part of the fast velocity body now residing just above the 660 km discontinuity once belonged to the Alpine slab, torn off by an event occurred at about 30–35 Ma.