Glacier Melting Triggers Massive Gravel Deposition in Central Italy's River Basins, Unveiling Deglacial Events From 1250 to 780 ka

Abstract

The purpose of this study was to prove the direct correlation of a successions of gravel‐clay beds recovered in borehole with the melt‐water pulses associated with the sea‐level oscillations indicated in the δ18O record in the time‐span preceding the 100‐kyr glacial cycles. Aimed at this scope, we provide combined 40Ar/ 39Ar and paleomagnetic constraints to a set of seven aggradational successions recovered from a 120 m deep borehole drilled in the buried Paleo‐Tiber delta in Rome (central Italy). The geochronologic constraints enable the correlation of each aggradational succession, characterized by a sudden transition from coarse gravel at the base to sandy clay sediments, with periods ofsea‐level rise indicated by the δ18O curve encompassing MIS 37 through MIS 19, from 1250 to 780 ka. This stratigraphy, provides a unique and unprecedented well‐dated evidence of glacial/deglacial events, matching the global benthic δ18O stack during this time frame. Furthermore, thisstudy validatesthe hypothesisthat gravel deposition in the catchment basin and the delta of the main rivers in central Italy is triggered by the melting of glaciers in the Apennines Mountain range. It demonstrates the significant potential of these deglaciation proxies to be used worldwide to unravel the chronology of glacio‐eustatic events.