Tectonic Evolution of the Apennines: ABSTRACT

Abstract

Italy's backbone is a fold-thrust belt of Cretaceous to Holocene tectonic age. It involves Paleozoic basement, thick Mesozoic carbonates, exotic terranes of western Mediterranean origin, and eastward migrating foredeeps. Foothills structures contain commercial mixtures of immature and mature gas. These structures and the giant Malossa field nearby encourage exploration. Plate motions, a quantitative tool in Apennine exploration, result from 2 components. Crustal coherence across the eastern Mediterranean invokes the motions between Europe and Africa, and Tertiary tectonics of the western Mediterranean add a local component. The Apennines are a collision belt with a polarity flip in the north and persistence in the south. Fossil arc material is scarcely recognized, but plate-size clastic sources include European foreland highs and Tethyan terranes in the north, and the Betic-Sardinian belt in the south. Recent volcanism occurs in 3 settings: arc, bent and fragmented foreland, and basin-range type extension. Refraction-seismic data suggest thrust repetitions of the Moho at odds with surface structure in polarity and location. In detail, these data are contestable, but their regional significance must be honored. It confirms estimates of stretching at Tethyan passive margins, flexing of visco-elastic foreland, 3-dimensional overlap of Europe, Alps, and Apennines, and, perhaps, crustal shear zones mapped at the surface. Style elements common to fold-thrust belts include ramps with decollements, duplexes, and blind thrusts. Interleaving thrust arcs suggest crustal control of ramps. Polyphase recumbent folds in several settings record the attaining of critical taper. Normal faulting is abundant and similar to the Idaho-Utah thrust belt. End_of_Article - Last_Page 798------------