--> ABSTRACT: Basin Geometry and Architecture of Alpine Passive Margin: Implication on the Mechanisms of Rifting, by Massimo Sarti, Alfonso Bosellini, and Edward L. Winterer; #91032 (2010)
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Basin Geometry and Architecture of Alpine Passive Margin: Implication on the Mechanisms of Rifting

Massimo Sarti, Alfonso Bosellini, Edward L. Winterer

Structural styles in the southern Alps reflect the mechanisms that extended the crust to form a Jurassic passive margin. The southern Alps consist of an array of Previous HithalfNext Hit-grabens, each with a west-tilted floor bounded on the west by an east-dipping master fault. Antithetic faults divide each Previous HithalfNext Hit-graben into a western depocenter and an eastern ramping marginal plateau, shallower and less subsident. The Previous HithalfNext Hit-grabens, from west to east, are M. Nudo-Arbostora, M. Generoso-Albenza, West Sebino-Botticino, East Sebino-Trento, and Belluno-Friuli. Typical antithetic faults, commonly with further Cenozoic displacements, include the Ballino and Carnian Prealps fault systems. Timing of Previous HithalfTop-graben formation shows an eastward-younging age progression, suggesting that extension propagated by steps into unextended crust over much of early and middle Liassic time.

The continent-facing dip of faults in the southern Alps is the reverse of the dip predicted by simple symmetrical extension models with only ductile extension in the lower lithosphere. However, it agrees with models in which low-angle shearing cuts through the entire lithosphere and results in structural asymmetry of conjugate margins. We suggest that the polarity of the observed shallow structures is the consequence of a gently east-dipping master shear cutting through the lithosphere at depth beneath the Brianconnais-southern Alps system.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.