Abstract
The deep structure of the southern Apennines (SA) accretionary wedge
is still debated since industrial seismic reflection and well data
provide reliable constraints only to a depth of about 10 km. As a
consequence, two directly linked questions regard (1) the shortening
in the accretionary prism (particularly within the buried Apulian
thrust units) and (2) the degree of involvement of the lower plate
basement (i.e., the Apulian crystalline basement). To address these
issues, we have constructed a regional section along a recently released
deep seismic reflection profile (CROP-04) which intersects the entire
SA. The resulting cross section, adequately constrained to a depth
of about 15 km, has been framed in a geodynamic scenario characterized
by the eastward roll-back of the westward subducting Apulo-Adriatic
lithosphere. On the basis of this section we speculate on the deep
structure, building both thin- and thick-skinned thrust models. A
cross-check of these end-members models against documented tectonic,
geophysical, and geochemical features shows that the thin-skinned
model is generally more consistent with the available data. The development
of basement slices with thicknesses of tens of kilometers is unlikely,
while it remains possible that the Apulian basement could have been
involved with its upper few kilometers. In the thin-skinned model,
the total shortening of the allochthonous units (i.e., Apennine and
Apulian carbonate platforms and Lagonegro basin) is estimated to
be greater than 280-300 km. Some 90 km of shortening can be attributed
to the Apulian thrust units.
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