The paleomagnetic investigation of the western Sicily Maghrebian belt has revealed since the 1970s that large clockwise rotations up to 140° with respect to the Hyblean-African foreland occurred synchronous with Tertiary shortening of the chain. The observation that rotations decrease stepwise from internal to external tectono-stratigraphic units led in the 1990s to a widely accepted model postulating that rotational thrust-sheet emplaced during forward orogenic propagation. More recently, other authors suggested that clockwise rotations from Sicily are conversely the result of late orogenic dextral strike-slip tectonics. Here we report on a paleomagnetic investigation of 30 Jurassic-Eocene sedimentary sites sampled mainly across the WNW-ESE Mt. Kumeta and Rocca Busambra ridges (Trapanese Unit), both bounded to the north by high-angle reverse faults with dextral strike-slip components. We find rotations of 110°–120° at faults of northern ridge margins, which decrease to 80°–90° at ~200 m to the south and rise again moving further south. Thus, an excess rotation of 20°–40° due to dextral-strike-slip shear is annulled to the regional rotational background of the Trapanese Unit at only 200 m from fault traces, translating to paleomagnetically calculated strike-slip offsets not exceeding 600 m. Further north, seven sites sampled in the Imerese Unit, tectonically stacked above the Trapanese Unit, yield a ~130° rotation. Thus, our data confirm that CW rotations in Sicily are predominantly related to thrust-sheet emplacement. Strike-slip tectonics has very limited relevance and gives local rotations that fade out at only 200 m from fault planes.

Speranza, F., Hernandez-Moreno, C., Avellone, G., Gasparo Morticelli, M., Agate, M., Sulli, A., et al. (2018). Understanding Paleomagnetic Rotations in Sicily: Thrust Versus Strike-Slip Tectonics. TECTONICS, 37(4), 1138-1158 [10.1002/2017TC004815].

Understanding Paleomagnetic Rotations in Sicily: Thrust Versus Strike-Slip Tectonics

Avellone, Giuseppe;Gasparo Morticelli, Maurizio;Agate, Mauro;Sulli, Attilio;Di Stefano, Enrico
2018-01-01

Abstract

The paleomagnetic investigation of the western Sicily Maghrebian belt has revealed since the 1970s that large clockwise rotations up to 140° with respect to the Hyblean-African foreland occurred synchronous with Tertiary shortening of the chain. The observation that rotations decrease stepwise from internal to external tectono-stratigraphic units led in the 1990s to a widely accepted model postulating that rotational thrust-sheet emplaced during forward orogenic propagation. More recently, other authors suggested that clockwise rotations from Sicily are conversely the result of late orogenic dextral strike-slip tectonics. Here we report on a paleomagnetic investigation of 30 Jurassic-Eocene sedimentary sites sampled mainly across the WNW-ESE Mt. Kumeta and Rocca Busambra ridges (Trapanese Unit), both bounded to the north by high-angle reverse faults with dextral strike-slip components. We find rotations of 110°–120° at faults of northern ridge margins, which decrease to 80°–90° at ~200 m to the south and rise again moving further south. Thus, an excess rotation of 20°–40° due to dextral-strike-slip shear is annulled to the regional rotational background of the Trapanese Unit at only 200 m from fault traces, translating to paleomagnetically calculated strike-slip offsets not exceeding 600 m. Further north, seven sites sampled in the Imerese Unit, tectonically stacked above the Trapanese Unit, yield a ~130° rotation. Thus, our data confirm that CW rotations in Sicily are predominantly related to thrust-sheet emplacement. Strike-slip tectonics has very limited relevance and gives local rotations that fade out at only 200 m from fault planes.
2018
Speranza, F., Hernandez-Moreno, C., Avellone, G., Gasparo Morticelli, M., Agate, M., Sulli, A., et al. (2018). Understanding Paleomagnetic Rotations in Sicily: Thrust Versus Strike-Slip Tectonics. TECTONICS, 37(4), 1138-1158 [10.1002/2017TC004815].
File in questo prodotto:
File Dimensione Formato  
Speranza_et_al-2017-Tectonics.pdf

Solo gestori archvio

Descrizione: PdF articolo. L'articolo è liberamente consultabile sul sito dell'editore all'URL https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017TC004815
Tipologia: Versione Editoriale
Dimensione 7.96 MB
Formato Adobe PDF
7.96 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/289751
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 19
  • ???jsp.display-item.citation.isi??? 17
social impact