Thermal and structural modeling of the Scillato wedge-top basin source-to-sink system: Insights into the Sicilian fold-and-thrust belt evolution (Italy)

Martina Balestra (1) , Sveva Corrado (1) , Luca Aldega (2) , Maurizio Gasparo Morticelli , Attilio Sulli (3) , Jean-Luc Rudkiewicz (4) , William Sassi (4)

1 ROMA TRE - Università degli Studi Roma Tre = Roma Tre University
2 UNIROMA - Università degli Studi di Roma "La Sapienza" = Sapienza University [Rome]
3 Università degli studi di Palermo - University of Palermo
4 IFPEN - IFP Energies nouvelles

Temperature-dependent clay mineral assemblages, vitrinite reflectance, and one-dimensional (1-D) thermal and three-dimensional (3-D) geological modeling of a Neogene wedge-top basin in the Sicilian fold-and-thrust belt and its pre-orogenic substratum allowed us to: (1) define the burial history of the sedimentary succession filling the wedge-top basin and its substratum, (2) reconstruct the wedge-top basin geometry, depocenter migration, and sediment provenance through time in the framework of a source-to-sink system, and (3) shed new light into the kinematic evolution of the Apennine-Maghrebian fold-and-thrust belt. The pre-orogenic substratum of the Scillato basin shows an increase in levels of thermal maturity as a function of stratigraphic age that is consistent with maximum burial to 3.5 km in deep diagenetic conditions. In detail, Ro% values range from 0.40% to 0.94%, and random ordered illite-smectite (I-S) first converts to short-range ordered structures and then evolves to long-range ordered structures at the base of the Imerese unit. The wedge-top basin fill experienced shallow burial (∼2 km) and levels of thermal maturity in the immature stage of hydrocarbon generation and early diagenesis. Vitrinite reflectance and mixed-layer I-S values show two populations of authigenic and inherited phases. The indigenous population corresponds to macerals with Ro% values of 0.33%–0.45% and I-S with no preferred sequence in stacking of layers, whereas the reworked group corresponds to macerals with Ro% values of 0.42%–0.47% and short-range ordered I-S with no correlation as a function of depth. Authigenic and reworked components of the Scillato basin fill allowed us to unravel sediment provenance during the Neogene, identifying two main source areas feeding the wedge-top basin (crystalline units of the European domain and sedimentary units of the African domain), and to detect an early phase of exhumation driven by low-angle extensional faults that predated Neogene compression.

Mots clés: Cenozoic deformation; Europe faults; Mesozoic sedimentary rocks tectonics; Tertiary; wedge-top basin; vitrinite reflectance; mixed layers illite-smectite; thermal modelling; source-to-sink systems; Sicilian fold-and-thrust belt

Domaines: Sciences de la Terre

Martina Balestra, Sveva Corrado, Luca Aldega, Maurizio Gasparo Morticelli, Attilio Sulli, et al.. Thermal and structural modeling of the Scillato wedge-top basin source-to-sink system: Insights into the Sicilian fold-and-thrust belt evolution (Italy). Geological Society of America Bulletin, 2019, 131 (11-12), pp.1763-1782. ⟨10.1130/B35078.1⟩. ⟨hal-02409671⟩