The architecture of an incipient oceanic basin: a tentative reconstruction of the Jurassic Liguria-Piemonte basin along the Northern Apennines–Alpine Corsica transect |
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| Authors: | Michele Marroni Luca Pandolfi |
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| Institution: | (1) Dipartimento di Scienze della Terra, Università di Pisa and Istituto di Geoscienze e Georisorse, CNR, Sezione di Pisa, Via S.Maria 53, 56126 Pisa, Italy |
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| Abstract: | In this paper, a scenario for the early evolution of the Jurassic oceanic Liguria-Piemonte basin is sketched. For this purpose,
four selected examples of ophiolite sequences from the Northern Apennines and Corsica are described and analyzed. In the External
Ligurian units (Northern Apennines), the ocean–continent transition of the Adria plate was characterized by a basement made
up of subcontinental mantle and lower continental crust, covered by extensional allochthons of upper crust. Both, the basement
rocks and the extensional allochthons are cut by basaltic dikes and covered by basalts and pelagic deposits. The conjugate
ocean–continent transition of the Corsica margin, represented by the Balagne nappe (Corsica), was composed of mantle peridotites
and gabbros covered by basaltic flows and minor breccias, that in addition include continent-derived clasts. By contrast,
the innermost (i.e., closest to the ocean) preserved area observed in the Internal Ligurian (Northern Apennines) and Inzecca
(Corsica) units consists of former morphological highs of mantle peridotites and gabbros, bordered by small basins where the
basement is covered by a volcano-sedimentary complex, characterized by ophiolitic breccias and cherts interlayered with basaltic
flows. The overall picture resulting from our reconstructions suggests an asymmetric architecture for the Liguria-Piemonte
basin with a central area bounded by two different transition zones toward the continental margins. This architecture can
be interpreted as the result of a rifting process whose development includes a final stage characterized by passive, asymmetric
extension of the lithosphere along an east-dipping detachment fault system. |
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| Keywords: | Ophiolites Ocean– continent transition Liguria-Piemonte basin Corsica Northern Apennines |
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