Crustal structure in the Southern Apennines from teleseismic receiver
functions
Geology, 36 (2):
155--158 (01.02.2008)DOI: 10.1130/G24065A.1
Zusammenfassung
While the upper crustal structure of the Southern Apennines is known,
lack of control on the deep structure allows competing thin-skinned
and thick-skinned models of the orogen. In thin-skinned models, the
detachment decouples a stack of rootless nappes from the basement.
In thick-skinned models, basement is involved in the most recent
phase of thrusting. To examine crustal structure, we use teleseismic
data from the Calabria-Apennine-Tyrrhenian/Subduction-Accretion-Collision
Network (CAT/SCAN) array in southern Italy. We use receiver functions
(RF) processed into a common conversion point stack to generate images
of the crust. Interpretation and correlation to geological structure
are done using inversions of individual station RFs. We focus on
a shallow discontinuity where P-to-S conversions occur. In the foreland,
it corresponds to velocity jumps between carbonate and clastic strata
with basement. A similar interpretation for the Apennines provides
the most parsimonious explanation and supports a thick-skinned interpretation.
In a thick-skinned reconstruction, the amount of shortening is much
smaller than for a thin-skinned model. This implies considerably
less Pliocene-Pleistocene shortening across the Apennines and suggests
an east-southeast motion of the Calabrian arc subparallel to the
southern Apennines rather than a radial expansion of the arc.