Pattern of extensional faulting in pelagic carbonates of the Unbria-Marche Apennines of central Italy

Journal Article · Tue May 01 00:00:00 EDT 1990 · Geology; (USA)

DOI:https://doi.org/10.1130/0091-7613(1990)018<0407:POEFIP>2.3.CO;2· OSTI ID:6213078

Alvarez, W ^[1]

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1. Univ. of California, Berkeley (USA)

The Umbria-Marche Apennines provide a new region in which the nature passive-margin extensional faulting can be studied in outcrop. In these dominantly pelagic carbonate rocks of Jurassic and Cretaceous age, horsts acted as shallow, nonvolcani seamounts, while tilted half grabens formed deeper basins. One well-exposed seamount-basin transition agrees in general with the model of listric normal faulting and tilted half grabens, but shows interesting and significant divergences when studied in detail. A small sedimentary wedge at the faulted margin of a horst-block seamount thickens unexpectedly toward the adjacent basin. This wedge developed because of local convex-upward curvature of the shallowest part of a fault which at depth must have concave-up, listric geometry. The local sedimentary wedge resulted from deposition on the hanging wall as it tilted, followed by differential compaction of younger limestones that lapped onto the gentle slope leading from the horst-block seamount toward the basin. The map pattern of listric normal faulting in the Umbria-Marche Apennines suggests that both principal strain axes were extensional, in contrast to the usual pattern of listric faults crossed by transfer faults.

• OSTI ID: 6213078
• Journal Information: Geology; (USA), Vol. 18:5; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ITALY
MOUNTAINS
GEOLOGIC FAULTS
CARBONATE ROCKS
CRETACEOUS PERIOD
DEFORMATION
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
JURASSIC PERIOD
LIMESTONE
SEDIMENTARY BASINS
STRAINS
TECTONICS
EUROPE
GEOLOGIC AGES
GEOLOGIC FRACTURES
MESOZOIC ERA
ROCKS
SEDIMENTARY ROCKS
WESTERN EUROPE
580000* - Geosciences