Abstract

A multidisciplinary study of drill core C45 from the Gulf of Policastro slop (Tyrrhenian Sea) was aimed at contributing to the biostratigraphy, paleoclimatology, tephrochronology, sedimentology and paleo-ecology of the region. The sedimentary sequence, Late Pleistocene-Holocene in age, was deposited during the 32-30 ka before present. Some subdivisions have been distringuished on the basis of sedimentological analyses. The succession recovered consists of silty-clay and clayey-silt with four interbedded levels rich in pyroclastic components. The sedimentation rate is variable, reaching the value of about 20 cm for 1.000 years. Turbidites have been mainly recognized in the lower part of last glacial sedimentary body (Late Pleistocene), whereas frequent pelagites have been found in the middle and upper part of the core which correspond to a deglaciation phase (Late glacial) and to the next post glacial transgression (Holocene). The pyroclastic horizons, a few centimetres in thickness, are related to the great eruptive events of the Somma Vesuvius and Phlegrean Fields except for one which belongs to the event known as Y3, widespread in the Mediterranean region, whose source area is still unknown. The present report also deals with the quantitative faunal analyses of foraminiferal and pteropod assemblages recovered from 59 samples of core, in order to reconstruct the paleoclimatic conditions of water masses at the core location. This shows that in the lower and middle part of sequence high productivity and oligotypic assemblages of Pteropods occur, mainly containing the subartic species Limacina retroversa. Also some taxa of planktonic foraminifers typical of subpolar-transitional waters as Globorotalia scitula, Neogloboquadrina pachyderma lx, Turborotalita quinqueloba were recognized. From 180 cm toward the top, these assemblages were replaced by others with temperate and/or warm-temperate species, with higher species diversity indicative of subtropical-tropical water masses (among which mainly Limacina inflata for the Pteropods and Globigerinoides spp. for planktonic Foraminifers). Paleoclimatic curves for the planktonic Foraminifers and Pteropods were inferred based on the algebraic sum of the cumulative percentages of cold and warm water indicators. They show that the basal and middle parts of the sequence can be referred to the last glaciation (Wurm) and that the assemblages reflect a clear Atlantic influence whereas the upper part shows characteristic species of western and eastern Mediterranean typical of Late Pleistocene-Holocene Epoch. The inferred climatic curves were compared: basically they are in good agreement but the climatic pulsations are less evident in the foraminifers curve. The most significant dated events are: the Last glacial maximum (about 19-18 ka BP), the Bolling-Allerod warm event (13-11 ka BP), the Younger Dryas cold-temperate event (about 11-10 ka BP), whose top marks the Upper Pleistocene-Holocene transition. The ages of these key events together with <sup>14</sup> C dating were used to calculate the sedimentation rates of the core. The palaeoecological results indicate that the time-evolution of the sedimentation, the productivity and the specific diversity of the assemblages (mainly of the Pteropods) were controlled by climatic and eustatic changes, and by volcanic events affecting the Tyrrhenian Sea during the time span considered.

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