The Age and Stratigraphy of Middle Pleistocene and Younger Deposits along the Gulf of Taranto (Southeast Italy)

Paul J. Hearty, Giuseppe Dai Pra

Abstract


Tectonically elevated siliciclastic marine terrace deposits dominate coastal areas in the province of Basilicata, while further east along the Salentine Peninsula, authigenic and biogenic fossiliferous limestones are most common. These limestones are often stratigraphically superimposed along the margins of the low-profile carbonate platform. Amino acid racemization geochronology (AAR) and radiometric methods have been used to date and correlate 14 coastal sections along 200 km of the Gulf of Taranto. This is accomplished by calibration of D-alloisoleucine/L-isoleucine (A/l) ratios with U-series and 14C dates which establishes an absolute age framework for marine transgressions, dune formation and pedogenesis. In addition, these data define the nature of the epimerization reaction as it proceeds toward equilibrium (A/I of ca. 1.30) for Helix and Glycymeris in timescales of 103, 105 and 106 of years. At least five shoreline complexes (littoral, eolian, and pedogenic depositional units) have been identified. Two middle Pleistocene transgressions are equated with Aminozones F and G. Aminozone H is associated with a third but is poorly defined. A late Pleistocene interglacial complex is bracketed by two aminozones. The earlier, Aminozone E, consists of widespread limestones, eolianites and thin soils, while the latter, Aminozone C, is less frequently preserved as marine calcarenite and dunes. Deposition during the Holocene (Aminozone A), however, was quite active as indicated by the numerous sequences of beaches, dunes and soils. The AAR method is useful for correlating coastal deposits over great distances, reconstructing paleoenvironments, establishing a tectonic history, and estimating ages of these events the Gulf of Taranto.

 

 


Keywords


Amino acid racemization; epimerization; geochronology; littoral deposits; shoreline stratigraphy; eustatic sea levels; interglacial periods; carbonate platform; tectonic uplift; Salentine Peninsula; Puglia and Basilicata Provinces

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