The aim of this research is to present a paleomorphological reconstruction of the buried incised valley of the Volturno River, across the coastal region connecting the northern Campania Plain and the Gaeta Bay during the Last Glacial cycle. The study is based on comprehensive set of onland borehole data and offshore reflection profiles and will attempt an interpretation of the Volturno incised valley as an example of a highly dynamic stratigraphic system dominated by volcanic activity during severe climatic changes. The volcaniclastic deposits originated by the Phlegrean Field caldera 39 ka eruption (Campania Grey Tuff - CGT) form the substrate for the Holocene and recent sedimentation. The digital surface model reconstructed for the upper CGT surface shows a 15-20 km wide Late Quaternary paleovalley incised by the Volturno River into the thick ignimbritic unit. The asimmetry of the southern valley flanks was shaped by the presence of an ancient river (Clanio River), reclaimed during the XVI century, that resulted in the enlargement of the valley and the formation of a complex deltaic system in the southern part. Correlation of stratigraphic data from the subsurface of the Volturno Plain with sequence stratigraphic interpretation of high-resolution (1kJ sparker) single channel reflection seismic profile offshore the Volturno river mouth indicates that the Volturno buried paleo-valley was likely incised throughout the Late Pleistocene - early Holocene, during the Last Glacial eustatic cycle. The boundary between the substratum of the paleo-Volturno valley and its sedimentary fill is marked by a well-developed unconformity and associated stratigraphic gap that separates the older Quaternary alluvial deposits and the Campania Ignimbrite (ca 40 ka BP) from the overlying uppermost Pleistocene-Holocene coastal prism entrenching the incised valley. The onset of the sea-level rise, that followed the climax of the Last Glacial Maximum since ca. 15 ka BP, caused marine ingression deep into the Volturno incised Valley and was associated with rapid backstepping and landward shift of depositional systems. Maximum marine flooding conditions are documented at 7,0-6,5 ka BP by the occurrence of prodeltaic deposit, that have been cored between 18 and 25 m beneath the surface. Since the middle Holocene, a progressive lowering of the Post Glacial sea-level rise created conditions favorable to early aggradation (6,5 -4,5 ka BP) and late stage progradation (< 4,5 ka), accompanied by seaward shift of depositional systems. This caused, in turn, a rapid filling of the accommodation space over the former incised valley, with the formation of the modern Volturno alluvial Plain, coastal lagoon and beach barrier system.
The Holocene stratigraphic architecture of the Volturno River delta (Southern Italy).
Ruberti D.
;Vigliotti M.
2018
Abstract
The aim of this research is to present a paleomorphological reconstruction of the buried incised valley of the Volturno River, across the coastal region connecting the northern Campania Plain and the Gaeta Bay during the Last Glacial cycle. The study is based on comprehensive set of onland borehole data and offshore reflection profiles and will attempt an interpretation of the Volturno incised valley as an example of a highly dynamic stratigraphic system dominated by volcanic activity during severe climatic changes. The volcaniclastic deposits originated by the Phlegrean Field caldera 39 ka eruption (Campania Grey Tuff - CGT) form the substrate for the Holocene and recent sedimentation. The digital surface model reconstructed for the upper CGT surface shows a 15-20 km wide Late Quaternary paleovalley incised by the Volturno River into the thick ignimbritic unit. The asimmetry of the southern valley flanks was shaped by the presence of an ancient river (Clanio River), reclaimed during the XVI century, that resulted in the enlargement of the valley and the formation of a complex deltaic system in the southern part. Correlation of stratigraphic data from the subsurface of the Volturno Plain with sequence stratigraphic interpretation of high-resolution (1kJ sparker) single channel reflection seismic profile offshore the Volturno river mouth indicates that the Volturno buried paleo-valley was likely incised throughout the Late Pleistocene - early Holocene, during the Last Glacial eustatic cycle. The boundary between the substratum of the paleo-Volturno valley and its sedimentary fill is marked by a well-developed unconformity and associated stratigraphic gap that separates the older Quaternary alluvial deposits and the Campania Ignimbrite (ca 40 ka BP) from the overlying uppermost Pleistocene-Holocene coastal prism entrenching the incised valley. The onset of the sea-level rise, that followed the climax of the Last Glacial Maximum since ca. 15 ka BP, caused marine ingression deep into the Volturno incised Valley and was associated with rapid backstepping and landward shift of depositional systems. Maximum marine flooding conditions are documented at 7,0-6,5 ka BP by the occurrence of prodeltaic deposit, that have been cored between 18 and 25 m beneath the surface. Since the middle Holocene, a progressive lowering of the Post Glacial sea-level rise created conditions favorable to early aggradation (6,5 -4,5 ka BP) and late stage progradation (< 4,5 ka), accompanied by seaward shift of depositional systems. This caused, in turn, a rapid filling of the accommodation space over the former incised valley, with the formation of the modern Volturno alluvial Plain, coastal lagoon and beach barrier system.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
