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Paleomagnetic evidence for a post-1.2 Ma disruption of the Calabria Terrane; consequences of slab breakoff on orogenic wedge tectonics

Fabio Speranza, Patrizia Macri, Domenico Rio, Eliana Fornaciari and Chiara Consolaro
Paleomagnetic evidence for a post-1.2 Ma disruption of the Calabria Terrane; consequences of slab breakoff on orogenic wedge tectonics
Geological Society of America Bulletin (May 2011) 123 (5-6): 925-933

Abstract

In the past few years, a wealth of paleomagnetic data gathered from Neogene sediments consistently showed that since ca. 10 Ma the Calabria terrane coherently drifted approximately 500 km ESE-ward from the Sardinian margin, and rotated 15 degrees -20 degrees clockwise (CW) as a rigid microplate between 2 and 1 Ma. Here we report on a high-resolution paleomagnetic investigation of the Crotone forearc basin of northern Calabria. The integrated calcareous plankton biostratigraphy indicates early Pliocene (Zanclean) to late early Pleistocene (Calabrian) ages for 29 successful paleomagnetic sites and/or sections. Unexpectedly, four domains undergoing distinct rotations are documented. Two blocks have undergone a CW rotation statistically undistinguishable, for both timing and magnitude, from the rigid Calabria rotation documented in the past. Two additional approximately 10-km-wide blocks yielded a 30.8 degrees + or -22.5 degrees and 32.0 degrees + or -9.2 degrees post-1.2 Ma counterclockwise rotation, likely due to left-lateral shear along two NW-SE fault zones. We infer that since advanced early Pleistocene times, after the end of the uniform CW rotation, left-lateral strike-slip tectonics disrupted the Calabria terrane, overwhelming a widespread extensional regime accompanying the Calabria drift since late Miocene times. Seismological evidence reveals that only the southern part of the Ionian slab subducting below Calabria is continuous, while beneath northern Calabria a slab window between 100 and 200 km depth is apparent. We suggest that the partial breakoff of the Ionian slab after 1 Ma induced the fragmentation of the Calabria wedge, and that strike-slip faults from the Crotone basin decoupled "inactive" northern Calabria from southern Calabria, still drifting towards the trench.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 123
Serial Issue: 5-6
Title: Paleomagnetic evidence for a post-1.2 Ma disruption of the Calabria Terrane; consequences of slab breakoff on orogenic wedge tectonics
Affiliation: Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
Pages: 925-933
Published: 201105
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 58
Accession Number: 2011-044427
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2011006
Illustration Description: illus. incl. 2 tables, sketch maps
N38°00'00" - N40°10'00", E15°45'00" - E17°00'00"
Secondary Affiliation: Universita di Padova, ITA, Italy
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201125
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