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Mid-Eocene mass wasting melanges in the context of wrench faulting along the oblique-convergent Corsica-Sardinia margin

Francesco Massari and Iginio Dieni
Mid-Eocene mass wasting melanges in the context of wrench faulting along the oblique-convergent Corsica-Sardinia margin
Italian Journal of Geosciences (October 2014) 133 (3): 381-395

Abstract

The Mid-Eocene clastic wedge with olistoliths of the Caporalino Unit and correlated units in Corsica are regarded as sedimentary melanges emplaced at shallow structural level by means of submarine, gravity-driven mass wasting processes in fault-bounded basins of the Corsican accretionary wedge. This occurred in the frame of synorogenic sinistral strike-slip motion generated by oblique convergence between the Iberia and Adria plates. During the final, Late Eocene collisional stage the melanges were overprinted and structurally reworked as olistostromal carpets at the base of the uppermost thrust sheets of the nappe stack (the Balagne-Nebbio Nappe). It is believed that the Corsica orogenic belt continued southwards, and that the present-day Sardinia behaved as foreland of the Alpine belt, as suggested by evidence of forebulge migration from Late Cretaceous onwards. However, the NE and SE sectors of Sardinia show different responses to the Mid-Eocene geodynamic event, as the related wrench faulting and transpressional deformation are well developed only in the NE part, the change being identifiable at the level of the Gulf of Orosei. We propose that the Orosei Canyon Line (OCL), an important lineament identified by Sartori et alii (2001), could have been active in Eocene times as a transform boundary preventing the southward prosecution of the Alpine subduction. The transpressional response of NE sector of Sardinia to the stress field was accompanied by accumulation of elongate clastic wedges by mass-wasting processes at the base of tectonic scarps. The wedges display several features comparable to those of Corsican melanges, and, although obviously generated in different geologic contexts, both are considered to be the expression of a peculiar Mid-Eocene geodynamic event of the Alpine orogenic belt.


ISSN: 2038-1719
EISSN: 2038-1727
Coden: BOGIAT
Serial Title: Italian Journal of Geosciences
Serial Volume: 133
Serial Issue: 3
Title: Mid-Eocene mass wasting melanges in the context of wrench faulting along the oblique-convergent Corsica-Sardinia margin
Affiliation: Universita di Padova, Dipartimento di Geoscienze, Padua, Italy
Pages: 381-395
Published: 201410
Text Language: English
Publisher: Societa Geologica Italiana, Rome, Italy
References: 103
Accession Number: 2014-105275
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch maps
N38°49'60" - N41°30'00", E08°15'00" - E09°45'00"
Country of Publication: Italy
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Societa Geologica Italiana. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201452
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