In the NW Italy southalpine plain the large (505 km2) Ivrea morainic amphitheatre (IA) develops at the outlet of the Dora Baltea River Valley. The IA forms a wide complex of lateral and terminal moraines and kame terraces, dated from the end of the Early Pleistocene (on paleomagnetic basis) to the end of the Late Pleistocene (14C radiometric and 10Be exposure ages). Some embedded paleosols and palustrine deposits within the glacial deposits, interpretable as interglacial layers, outcrop along watercourses cutting the IA outer and inner edges. These stratigraphic markers allowed the subdivision of the glacigenic succession into ten alloformations corresponding to as many glaciations. So a potentially complete glacigenic succession outcrops, which can be possibly correlated to the whole sequence of the main Quaternary glaciations of the marine oxygen isotope stratigraphy from MIS 20 to MIS 2. In the middle of the IA left lateral sector a layer of gyttja was found into a deep stream incision. It separates two sequences of tills of Middle Pleistocene age, characterized by Munsell soil colours of hue 5YR. The paleobotanical analysis of this layer will possibly allow an evaluation of its paleoclimatic meaning and support to the IA climatostratigraphic subdivision.
Stratigraphical subdivision of the Middle Pleistocene glacigenic sequence of the Ivrea amphitheatre (Piedmont, NW Italy)
GIANOTTI, FRANCO;
2011-01-01
Abstract
In the NW Italy southalpine plain the large (505 km2) Ivrea morainic amphitheatre (IA) develops at the outlet of the Dora Baltea River Valley. The IA forms a wide complex of lateral and terminal moraines and kame terraces, dated from the end of the Early Pleistocene (on paleomagnetic basis) to the end of the Late Pleistocene (14C radiometric and 10Be exposure ages). Some embedded paleosols and palustrine deposits within the glacial deposits, interpretable as interglacial layers, outcrop along watercourses cutting the IA outer and inner edges. These stratigraphic markers allowed the subdivision of the glacigenic succession into ten alloformations corresponding to as many glaciations. So a potentially complete glacigenic succession outcrops, which can be possibly correlated to the whole sequence of the main Quaternary glaciations of the marine oxygen isotope stratigraphy from MIS 20 to MIS 2. In the middle of the IA left lateral sector a layer of gyttja was found into a deep stream incision. It separates two sequences of tills of Middle Pleistocene age, characterized by Munsell soil colours of hue 5YR. The paleobotanical analysis of this layer will possibly allow an evaluation of its paleoclimatic meaning and support to the IA climatostratigraphic subdivision.
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