Paleocene magneto-biostratigraphy and climate-controlled rock magnetism from the Belluno Basin, Tethys Ocean, Italy

The Paleocene South Ardo section consists of ~113m of red to gray marls and calcareous marls continuously exposed along the South Ardo riverbed in the Venetian Southern Alps of Northern Italy. Magneto-biostratigraphic data imply that the section extends from magnetic polarity Chron C29r across the Cretaceous-Paleogene boundary to Chron C24r across the Paleocene-Eocene boundary, and from calcareous nannofossil Micula murus Zone in the Maastrichtian to Zone NP10 in the Ypresian. The average sediment accumulation rate, calculated by means of magnetic-polarity correlation with published Paleocene time scales, was found to vary from ~1.2 to 23m/Myr throughout the section, and was used to calibrate the age of key calcareous nannofossil biohorizons, thus augmenting the resolution of existing time scales, as well as to migrate to the time domain the observed vertical variations of rock-magnetic properties. Our analyses allow to extend back into the Paleocene the temporal correlation between rock-magnetic properties and Earth's long-term climate previously observed in the neighboring late Paleocene-early Eocene Cicogna section. In detail, the composite South Ardo-Cicogna rock-magnetic dataset, which extends from ~65Ma to 52.5Ma, reveals that the warmer and more humid the climate, the higher the detrital hematite content of the sediments relative to maghemite/magnetite. We infer that our climate-controlled rock-magnetic curve reflects the efficiency of the silicate weathering mechanism to buffer pCO 2 long-term variations, and thus Earth's climate, during the Paleocene-Eocene. © 2012 Elsevier B.V.