Abstract

A detailed micropaleontological and geochemical study of early Pliocene limestone-marl couplets from the Capo Spartivento section in Calabria, southern Italy indicates that the rhythmic sedimentation pattern is related to changes in surface water productivity. Relative to the marls, the limestone units are typically marked by higher abundances of the planktonic foraminifera G. bulloides , higher numbers of benthic foraminifera, higher delta 13 C values and lower delta 18 O values. These characteristics are interpreted as indicating that cool, highly productive conditions existed during the deposition of the limestone units. Time series analysis indicates that a significant amount of the variance in the carbonate record is associated with periods of 17 and 23 ky. Similarly, cross-spectral analysis demonstrates that the precession signal and the carbonate record are strongly coherent over the 23 ky frequency band. We propose a model in which intensified winds associated with precession maxima result in increased upwelling, higher productivity, and limestone deposition.

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