Crustal Structure in the Southern Apennines from Teleseismic Receiver Functions

Abstract

While the upper structure of the Southern Apennines is known, lack of control on the deep structure allows competing thin-skin and tick-skin models of the orogen. In thin-skin models the detachment decouples a stack of rootless nappes from the basement. In the tick-skin models, besement is involved in the most recent phase of thrusting. To examine crustal structure, we use teleseismic data from the CAT/SCAN array in southern Italy. We use receiver functions (RF) processed into a Common Conversion Point (CCP) stack to generate images of the crust. Interpretation and correlation to geological structure is 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 tick-skin interpretation. In a thick-skin reconstruction, the amount of shortening is much smaller than for a thin-skin model. This implies considerably less Plio-Pleistocene shortening across the Apennines and suggests an E-SE motion of the Calabrian Arc subparallel to the southern Apennines rather than a radial expansion of the Arc.