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Central Mediterranean and Carpathians |
1 Geomare Sud, Institute of Marine Science, CNR, Via Vespucci 10, Napoli, Italy
2 Dipartimento di Scienze della Terra, Università di Napoli, Largo San Marcellino 10, Napoli, Italy
3 Department of Geological Sciences, University of Plymouth PL4 8AA, UK
After rigorous geological and petrological study to exclude all Miocene rock samples that may have been affected by post-deposition disturbances and selecting only sites where the Miocene rocks appear to be rigidly attached to their Mesozoic substrate, over 100 samples were collected from the Monte Matese region. Over 200 oriented specimens, cut from these samples, were subjected to rigorous thermal and alternating field demagnetization. Strict criteria for the definition and within-site consistency of remanent vectors showed that most sites were dominated below 200°C or 20 mT by a magnetization associated with the present geomagnetic field direction. In almost all sites, any higher coercivity or blocking temperature components were inconsistent with the exception of one locality near Pescorosito. Re-sampling of two outcrops at this locality, 100 m apart, provided 26 samples that met all of the geological, petrological and palaeomagnetic criteria. The low temperature/coercivity component is the same as the present geomagnetic field in the locality, but all samples from eight of the nine sites have identical remanence vectors between 200 and 400/450°C. Petrological and tectonic considerations imply that this remanence must be associated with very early diagenesis and is thus probably of Mid-Miocene but possibly Early Miocene age. As these sites are autochthonous relative to their Mesozoic basement, they indicate a 40° anticlockwise rotation of the Monte Matese block, relative to Apulia, since Mid-Miocene times. Thus most of the post-Early Cretaceous rotation of this block has occurred since Mid-Miocene times. It is suggested that similar age constraints may also apply to other rotated blocks within the Southern Apennines.
