Holocene uplift rates and historical rapid sea-level changes at the Gargano Promontory, Italy

Abstract

This paper uses a combination of geomorphological and radiometric data from the northern coast of the Gargano promontory (comprising the Fortore River coastal plain and Punta delle Pietre Nere) to reconstruct Holocene uplift rates. The coastal plain consists of a sandy progradational beach sequence that extends seawards from the base of a relict cliff. This cliff probably marks the maximum position reached by the Holocene transgression. Altimetric data compared with the age of beach deposits and the available eustatic sea-level curves indicate an average Holocene uplift rate of 1.5 mm yr(-1). A similar uplift rate has been estimated by dating a bioherm constituted of calcareous algae, Vermetids and subordinately by Cladocora caespitosa (L.), which crops out in the locality of Punta delle Pietre Nere. This deposit, which was previously assigned an interglacial age, yielded a mid-Holocene age by means of Th/U and C-14 age determinations. Our observations also reveal evidence for coseismic deformation along the northern coast of the Gargano promontory during the last millennium. Vertical displacements of >0.5 m have affected the Punta delle Pietre Nere coastal block, and were preceded by periods of slow coastal subsidence, which increased rapidly shortly before a major earthquake. Copyright (C) 2002 John Wiley Sons, Ltd