The Santa Lucia Nappe (Alpine Corsica): paleotectonic heritage and deformation history

The Santa Lucia Nappe is a continental-derived unit exposed East of Corte, in central Alpine Corsica (Durand Delga 1984; Rossi et al., 1996).  The unit includes a peculiar lower- to mid-crustal section, exposing mafic and felsic granulites, with an overall structure, Permian age of tectono-metamorphic and magmatic history (Caby et al., 2002; Zibra et al, 2010, 2012), like that of the Ivrea Zone (northwestern Alps), and of the Sila-Stilo unit in the Calabria terrane (Molli et al., 2020). Moreover, the Santa Lucia Nappe includes a Cretaceous metasedimentary cover, with a basal conglomerate transitioning to a calcareous flysch, which shows affinities with calcareous-marly Ligurian Flysch (Amaudric Du Chaffaut 1972; Rieuf 1980). The Santa Lucia Nappe recorded a polyphase Alpine tectonic evolution, developed under greenschist-facies conditions (Zibra, 2006; Vitale-Brovarone et al., 2013)

Because of its unique lithological association, the structural position, significance, and paleotectonic attribution of the Santa Lucia Nappe are  the subject of a long-standing debate. These topics are here re-discussed, based on our data collected in the last two decades of field work.

Our observations allow: (i) to document the Alpine deformation structures affecting both basement and cover sequence, their styles and distribution; (ii) to analyze the structural characters and kinematics of its basal tectonic contacts; (iii) to confirm its tectonic position with respect to the “Schistes Lustres”- composite Nappe system; and, finally, (iv) to propose an original interpretation of its internal architecture. The latter results from the tectonic inversion of pre-Cretaceous high-angle faults, which were originally arranged in an east-dipping, domino-like system, which affected the already exhumed and exposed basement, formerly part of a Permian regional-scale transtensional shear zone.