Developing a realistic model of sequence stratigraphy from the subsurface of modern alluvial plains is an important first step toward a successful three-dimensional representation of aquifer systems. The good stratigraphic framework available for the Quatemary of the Po Basin (northem Italy), combined with the scarce degree of tectonic deformation and the well known eustatic and climatic history, allow to define reliable aquifer geometries and portray high-resolution stratigraphic architecture with climate and sea-level changes as forcing mechanisms. Stratigraphic architecture within non-marine strata reveals distinctive cyclic changes in lithofacies and channel stacking patterns (TransgressiveRegressive sequences) falling in the Milankovitch (100 ka) band. Transgressive surfaces constitute basin-wide stratigraphic markers that show easier recognition , greater extent and higher correlation potential than sequence boundaries. The transgressive surfaces are marked by abrupt facies changes from amalgamated fluvial-channel sands to mud-dominated floodplain deposits with isolated channel bodies and organic horizons (transgressive alluvial deposits or TST). This interval grades upward into thick alluvial plain deposits showing increased channel clustering and sheet-like geometries (regressive alluvial deposits , including HST, FST, and LST). Latera! tracing of the transgressive surfaces into distai areas allows the establishment of the physical linkage between alluvial an d marine deposits. The repetitive alternation of fluvial-channel and floodplain deposits is paralleled by a distinctive pollen signature, showing a strict relationship between T -R sequences and interglacial/glacial cycles. Particularly, the transgressive surfaces correlate invariably with the onset of forested conditions during interglacials , whereas return to alluvial sedimentation correlates with abrupt change to open vegetation conditions during glacials.
Climatic signature of transgressive-regressive sequences from Quaternary alluvial deposits of the Po Plain (Italy)
SARTI, GIOVANNI;
2007-01-01
Abstract
Developing a realistic model of sequence stratigraphy from the subsurface of modern alluvial plains is an important first step toward a successful three-dimensional representation of aquifer systems. The good stratigraphic framework available for the Quatemary of the Po Basin (northem Italy), combined with the scarce degree of tectonic deformation and the well known eustatic and climatic history, allow to define reliable aquifer geometries and portray high-resolution stratigraphic architecture with climate and sea-level changes as forcing mechanisms. Stratigraphic architecture within non-marine strata reveals distinctive cyclic changes in lithofacies and channel stacking patterns (TransgressiveRegressive sequences) falling in the Milankovitch (100 ka) band. Transgressive surfaces constitute basin-wide stratigraphic markers that show easier recognition , greater extent and higher correlation potential than sequence boundaries. The transgressive surfaces are marked by abrupt facies changes from amalgamated fluvial-channel sands to mud-dominated floodplain deposits with isolated channel bodies and organic horizons (transgressive alluvial deposits or TST). This interval grades upward into thick alluvial plain deposits showing increased channel clustering and sheet-like geometries (regressive alluvial deposits , including HST, FST, and LST). Latera! tracing of the transgressive surfaces into distai areas allows the establishment of the physical linkage between alluvial an d marine deposits. The repetitive alternation of fluvial-channel and floodplain deposits is paralleled by a distinctive pollen signature, showing a strict relationship between T -R sequences and interglacial/glacial cycles. Particularly, the transgressive surfaces correlate invariably with the onset of forested conditions during interglacials , whereas return to alluvial sedimentation correlates with abrupt change to open vegetation conditions during glacials.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
