Strati graphical studies on the lower valley of Peschio di Iorio in Abruzzo assisted to define the depositional, erosive and pedogenetic phases that occurred after the last glacial maximum in the area. The chronology of deposits was obtained on the basis of sediments of glacial origin and a soil developed from the weathering of a tephra layer, which is widespread throughout Central and Southern Italy, and of three 14 C dates. The principal climatic and environmental events as indicated by sediments are: a) Presence of glaciers at the valley-head, which flowed into the Peschio di Iorio valley, with the snow line descending to altitudes markedly lower than 1800 m. b) A rise in temperature soon after 18,000 years B.P., which was accompanied by the rapid melting of glaciers and sedimentation of fluvioglacial deposits, c) A phase of stream activity, in presence of irregular precipitation and/or low temperatures hindering the development of abundant vegetation on the valley slopes, d) A phase of fluvial erosion favoured by probably rather regular precipitations and by a scarce contribution of material from the slopes, e) Tephra fall of "Neapolitan Yellow Tuff "(12,300±300 years BP.) and its partial colluvial re-sedimentation, in a time more recent than 8,990±80 years B.P. Re-sedimentation would have taken place during a period characterized by seasonal or irregular precipitations, f) A phase of pedogenesis with development of an andosoil all over the valley floor, which started after 8,990±80 years B.P. During the phase of pedogenesis, the area would have been under a regime of regular and/or abundant precipitations, g) A phase of colluvial deposition and covering of the andò soil on the valley floor which began around 6,900±85 years B.P. This phase indicates a negative variation or an increase - even if not much marked - of the rainfall seasonal regime, h) A phase of pronounced linear erosion, which was caused by abundant precipitations and occurred in a period well after 6,900±85 years B.P. and before 3,770±80 years B.P. i) A phase of alluvial and colluvial deposition with the covering of the andò soil still present at the foot of slopes. If due to natural causes, this phase, which occurred after 3,770±80 years B.P., would imply a rainfall decrease and/or a markedly seasonal rainfall regime.
Post-glacial deposits of the peschio di iorio lower valley (pescasseroli, national park of abruzzo, central Italy): Dating and paleoclimatic interpretation [I depositi post-glaciali della bassa valle peschio di iorio (Pescasseroli, Parco Nazionale D'abruzzo): Datazione e interpretazione paleoclimatica.]
Giraudi, C.
1997-01-01
Abstract
Strati graphical studies on the lower valley of Peschio di Iorio in Abruzzo assisted to define the depositional, erosive and pedogenetic phases that occurred after the last glacial maximum in the area. The chronology of deposits was obtained on the basis of sediments of glacial origin and a soil developed from the weathering of a tephra layer, which is widespread throughout Central and Southern Italy, and of three 14 C dates. The principal climatic and environmental events as indicated by sediments are: a) Presence of glaciers at the valley-head, which flowed into the Peschio di Iorio valley, with the snow line descending to altitudes markedly lower than 1800 m. b) A rise in temperature soon after 18,000 years B.P., which was accompanied by the rapid melting of glaciers and sedimentation of fluvioglacial deposits, c) A phase of stream activity, in presence of irregular precipitation and/or low temperatures hindering the development of abundant vegetation on the valley slopes, d) A phase of fluvial erosion favoured by probably rather regular precipitations and by a scarce contribution of material from the slopes, e) Tephra fall of "Neapolitan Yellow Tuff "(12,300±300 years BP.) and its partial colluvial re-sedimentation, in a time more recent than 8,990±80 years B.P. Re-sedimentation would have taken place during a period characterized by seasonal or irregular precipitations, f) A phase of pedogenesis with development of an andosoil all over the valley floor, which started after 8,990±80 years B.P. During the phase of pedogenesis, the area would have been under a regime of regular and/or abundant precipitations, g) A phase of colluvial deposition and covering of the andò soil on the valley floor which began around 6,900±85 years B.P. This phase indicates a negative variation or an increase - even if not much marked - of the rainfall seasonal regime, h) A phase of pronounced linear erosion, which was caused by abundant precipitations and occurred in a period well after 6,900±85 years B.P. and before 3,770±80 years B.P. i) A phase of alluvial and colluvial deposition with the covering of the andò soil still present at the foot of slopes. If due to natural causes, this phase, which occurred after 3,770±80 years B.P., would imply a rainfall decrease and/or a markedly seasonal rainfall regime.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
