Page 1 - 68_1_001_021

Anna/es Societatis Geologorum Poloniae (1998), vol. 68: 1-21.

NEOTECTONIC EVENTS AND KINEMATICS OF
RHEGMATIC-LIKE BASINS IN SICILY AND ADJACENT AREAS.

IMPLICATIONS FORA STRUCTURAL MODEL OF THE
TYRRHENIAN OPENING

Fabrizio NIGRO

Department ofGeology and Geodesy, University ojPalermo, C.so Tukory n. 131, 90134, Palermo, Italy

Nigro, F., 1998. Neotectonic events and kinematics of rhegmatic-like basins in Sicily and adjacent areas.
Implications fora structural mode! ofthe tyrrhenian opening. Ann. Soc. Geo!. Polon., 68: 1-21.

Abstract: The last few Ma kinematic history ofthe Southern peri-Tyrrhenian orogenic belt has been reconstructed
with the purpose of delineating a possible mode! of its recent geodynamic evolution. Unpublished field survey
data, geophysical soundings, aerial photographic support and a review of literature have been utilised in order to
propose a deep structural mode! ofmainland Sicily and adjacent off-shore areas.

A review of the published geophysical data and the interpretation of some published seismic profiles, coming
from the offshore areas, facilitate the neotectonic structural setting of the Centrai Mediterranean. The observed
fie! d geometries of the Sicily mainland, and a comparison with the marine data, are used to formulate a dynamic
mode!, characterised by the development of severa! mega-shear systems, related to the northward Afì-ica motion
and active since the late Miocene-early Pliocene, superimposed onto a previous very complicated mobile belt
geometri es, that controlled the opening of severa! rhegmatic-like basins.

Abstrakt: W celu skonstruowania wsp6lczesnego modelu ewolucji poludniowego peri-tyrrenskiego pasa oroge-
nicznego dokonano rekonstrukcji jego kinematycznej historii w ostatnich kilku milionach lat. Dost~pne w litera-
turze dane geofìzyczne i interpretacje profili sejsmicznych usytuowanych na Morzu Tyrrenskim umozliwily poz-
nanie neotektonicznej struktury centralnej cz~sci Morza Sr6dziemnego. Obserwowane na Sycylii struktury tekto-
niczne i ich por6wnanie z wynikami badan na obszarach morskich zostaly ui:yte do skonstruowania dynamiczne-
go modelu rozwoju licznych system6w wielkoskalowych sci~é (mega-shear) zwi1tzanych z ruchem Afryki ku p61-
nocy. Systemy te byly aktywne od p6inego miocenu do wczesnego pliocenu, oraz zostaly nalozone na wczdniej-
szy bardzo skomplikowany mobilny pas strukturalny, kt6ry kontrolowal otwieranie si~ basen6w typu regmatycz-
nego.

Key words: Neotectonic, Tyrrhenian, rhegmatic basins.

Manuscript received 17 lune 1997, aceppted 3 February 1998

INTRODUCTION

The Tyrrhenian Sea is interpreted as a basin with thin tors, ali related to Tyrrhenian stretching and evolution. The
continental/oceanic crust, superimposed onto the Europe- main trends that have been recognised are E-W, NW-SE
Africa Collisional Thrust Belt since the late Miocene. West- and NE-SW Ali these cut the E-W trending Sicily Thrust
wards, this basin is bordered by a fragment of the Alpine Belt. The main NW-SE and NE-SW trending fault systems
Belt (Sardinia and Corsica), and eastwards and southwards (generally with strike-slip movements) mostly outcrop in
by the Apennine-Sicily Belt. North and Centrai Sicily, where they stretch and/or truncate
the previous compressive thrust imbricates of the Thrust
The large extension and the oceanization in the centrai Belt. These systems are explained as E-W trending strike-
parts of the basin and the attendant compression in the pre- slip associated fault mega-riedels. Some of these recent
vious deformed Apennine-Sicily Thrust Belt, ali related to structures, which outcrop more frequently, are interpreted as
the progressive spreading of the Tyrrhenian Sea, created in the result of different scale and strike-slip movements that
the Sicily mainland a complex sequence of alternating ex- have produced positive and negative flower structures cut-
tensional and compressional tectonic events. ting, in places, the previous compressional structures not
older than 3 or 5 Ma (Maghrebides Terrains).
Some of field evidences, expressed by the neotectonic
fault systems affecting the studied segment of the Centrai Moreover, along the Northern and Eastern Sicilian
Mediterranean, show different trends and kinematic indica-