Basin geometry and architecture of alpine passive margin: Implication on the mechanisms of rifting
- Universita della Calabria, Castiglione Cosentino Scalo (Italy)
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 half-grabens, each with a west-tilted floor bounded on the west by an east-dipping master fault. Antithetic faults divide each half-graben into a western depocenter and an eastern ramping marginal plateau, shallower and less subsident. The half-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 half-graven 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. The authors 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 systems.
- OSTI ID:
- 5749416
- Report Number(s):
- CONF-8809346-; CODEN: AABUD
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 72:8; Conference: Mediterranean Basins conference and exhibition, Nice (France), 25-28 Sep 1988; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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