--> ABSTRACT: Controls of Structural Inheritance in Normal Fault Propagation and Extensional Basin Segmentation: The Crati Basin, Northern Calabria, Italy, by Spina, Vincenzo; Tondi, Emanuele; Mazzoli, Stefano; #90135 (2011)

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Controls of Structural Inheritance in Normal Fault Propagation and Extensional Basin Segmentation: The Crati Basin, Northern Calabria, Italy

Spina, Vincenzo 1; Tondi, Emanuele 2; Mazzoli, Stefano 3
(1)Geosciences Division, TOTAL E&P Italia, Rome, Italy. (2) Earth Sciences, University of Camerino, camerino, Italy. (3) Earth Sciences, University of Naples "Federico II", Naples, Italy.

The western sector of the Calabrian Arc is considered a classic extensional domain that developed as a result of subduction rollback and related back-arc opening since Late Miocene times.

However, the development of the back-arc domain is controlled by major strike-slip faults related to the heterogeneous nature of the Adria lithosphere and accommodating the SE migration of the Calabrian Arc. Since Middle Miocene to Lower Pleistocene, en-échelon NW-SE oriented left-lateral strike-slip faults exerted a major control on the tectonic evolution of northern-central Calabria. A series of extensional basins also developed in the area since the Plio-Pleistocene, being linked with, and segmented by these strike-slip faults.

The Crati Basin developed in the northern portion of the Calabrian Arc, being filled by Tortonian to Lower-Middle Pleistocene marine to deltaic deposits. Strike-slip faults and associated shortening at contractional jogs affected the basin fill during the early stages of its evolution. Since the Middle Pleistocene, N-S striking normal faults began to form, controlling the basin architecture.

The tectonic evolution of the Crati Basin has been investigated by the integration of field mapping, the construction of geological cross sections and bio-stratigraphic analyses with the interpretation of 2D seismic data. Seismic interpretation, used to constrain the structure of the basin at depth, confirmed that the master fault of the extensional fault system controlling the Crati Basin is represented by a blind fault dipping towards the west. This indicates that the Crati Basin may be interpreted as a half-graben that formed since Middle Pleistocene time. A minimum value of cumulative vertical displacement of ca. 600 m has been unraveled for the central sector of the Crati Basin since Middle Pleistocene times. This yields a vertical strain rate of ca. 0.9 mm/y during the last 700 ka.

Normal faults started to develop in the southernmost sector of the basin, where they abut against pre-existing strike-slip faults. It is envisaged that strike-slip faults, becoming progressively inactive and working as persistent barriers, inhibited the propagation towards the south of the newly formed normal faults, which therefore propagated towards the north, where such barriers were absent.

 

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.