Tracking Paleodrainage in Pleistocene Foreland Basins

摘要

Foreland basins are comprehensive stratigraphic archives, from which many details of the tectonic history of associatedorogens can potentially be retrieved by quantitative provenance analysis of sedimentary sequences. Because of complexbasin-fill architecture, however, provenance diagnoses often remain ambiguous. Trends in sediment compositioncannot be safely interpreted as documenting paleotectonic or paleoclimatic changes whenever paleodrainage shiftsrepresent an equally reasonable alternative. Understanding drainage patterns is thus a fundamental step in correctlyunraveling tectonic and climatic events that punctuate the erosional evolution of mountain belts. In this study, wefocus on well-studied Quaternary subsurface successions of the Po Plain to illustrate a quantitative method of paleodrainageanalysis. This method, based on high-resolution petrographic and heavy-mineral data from modern andPleistocene sands, allowed us to objectively reconstruct the drainage changes of Po River tributaries triggered bymajor Alpine glaciations in the past million years.