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AGU: Paleoceanography

 

Keywords

  • climate changes
  • coastal stratigraphy
  • 40Ar/39Ar dating

Index Terms

  • Paleoceanography: Astronomical forcing
  • Paleoceanography: Milankovitch theory
  • Geochronology: Radioisotope geochronology
Abstract
Cited By
 

Abstract

History of glacial terminations from the Tiber River, Rome: Insights into glacial forcing mechanisms

Fabrizio Marra

Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy

Fabio Florindo

Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy

Enzo Boschi

Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy

We document the aggradational history of the Tiber River delta through the last 17,000 years by means of 17 new 14C ages from peat or wood collected from the delta sediment. An abrupt change in sediment clast size, grading from gravel to clay, occurred between 13.63 (±0.20) and 12.80 (±0.15) ka, indicating that it was synchronous with the last glacial termination, with no appreciable phase lag. Knowing this phase relationship enables us to reduce the magnitudes of age uncertainties for aggradational sections corresponding to glacial terminations IX through III, which we had dated previously by 40Ar/39Ar methods. Glacial terminations VIII, VI, and IV precede beyond 95% confidence the ages predicted by Northern Hemisphere summer insolation maxima. Additionally, we find that each of these seven glacial terminations follows particularly mild insolation minima, which we suggest may be regarded as the preconditioning factor to trigger a glacial termination.

Received 14 September 2007; accepted 1 February 2008; published 30 April 2008.

Citation: Marra, F., F. Florindo, and E. Boschi (2008), History of glacial terminations from the Tiber River, Rome: Insights into glacial forcing mechanisms, Paleoceanography, 23, PA2205, doi:10.1029/2007PA001543.

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