We present the preliminary results of a ~ 230 m deep borehole (CN1) drilled in the eastern part of the Paganica-San Demetrio-Castelnuovo Basin (PSC) (L'Aquila, central Italy), at the top of the Castelnuovo hill within the Valle Daria paleosurface (Fig. 1). The PSC is a NW-SE trending graben bordered by active normal faults and filled by Plio-Quaternary deposits (Fig. 2). The oldest ones, largely outcropping in the Valle Daria area, pertain to the San Demetrio-Colle Cantaro Synthem and are composed by several formations, laterally interfingered each other, representing different depositional environments of the Paleolake San Nicandro (Fig. 2) (Cosentino et al., 2017; Nocentini et al., 2017; Nocentini et al., 2018). The deep lacustrine facies (San Nicandro Fm. - SNF) is formed by laminated to massive whitish calcareous silts, bearing an endemic ostracod assemblage mainly composed by Caspiocypris ssp. (Spadi et al., 2016), allowing to ascribe the SNF to a late Piacenzian-Gelasian age (Cosentino et al., 2017). The outcropping part of the SNF, usually less than 50 m thick, shows a normal magnetic polarity in the basal 10 m, passing upwards to a reverse polarity. In addition, in the upper portion of the SNF, close to Castelnuovo village, three blackish tephra layers are present. Starting from these premises, the Castelnuovo deep borehole (CN1) was realized to investigate, in a palaeoenvironmental and palaeoclimatic perspective, the early sedimentary infilling of the PSC and the evolution of the lacustrine system. The borehole reached a depth of 229.30 m b.g.l., drilling a succession mainly composed by cyclic alternations of fine-grained laminated and massive sediments (Fig. 3). The cyclic variations of different parameters among which the CaCO3 content, the granulometry, the sediment colour and the magnetic susceptibility testify that sedimentation was controlled by orbital and climatic oscillations (Fig. 3). In detail, the upper part of the well-log (<71.60 m), partly matching the outcropping succession, is characterized by the typical features of the SNF, consisting of a cyclic alternation of white calcareous silts and light grey clayey-silts couplets, often separated by a thin oxidized silty-sandy layer. In this interval, the CaCO3 content cyclically ranges between 50% and 90%, mostly occurring as lacustrine endogenic calcite. Between 71.60 and 118.80 m, clayey levels become more abundant and thicker and organic-rich clay levels appear, whereas minima CaCO3 contents are periodically recorded, around 25%. From 118.80 to 154.70 m, massive to laminated over-consolidated organic-rich clays are predominant, while calcareous silty levels become occasional and thin. In the first meters od this interval the CaCO3 content drops down, showing minimum values lower than 10%. From 154.70 to 194.8 m the sequence is formed by alternations of clayey-silts and laminated whitish calcareous silts, while down to 223.30 m it is composed by alternations of clays, marls and clayey-gravels, with coarser sediments becoming more and more frequent. Below 223.30 m, fine grain deposits almost disappear, passing to coarse poligenic calcareous breccias with rare clayey-silty layers. Several centimetric thick tephra layers occur in the first 105 meters of the sedimentary core CN1 and outcropping sections of the deep-lake deposits of the San Nicandro Formation (Fig. 3). These tephras share a common lithology of greyish ash made up of moderately vesicular glass shards, clinopyroxene, plagioclase, and minor orthopyroxene. Glasses and whole rock have a calc-alkaline intermediate composition ranging from basaltic-andesite to andesite, with slightly variable major and trace element contents. This composition is similar to the ? 2 Ma old volcanic rocks found in deep boreholes in Campanian Plain, southern Italy (Albini et al., 1980; Barbieri et al., 1979: Di Girolamo et al., 1976) (Fig. 4a). Incompatible trace elements normalised to the primordial mantle display typical subduction-related patterns with troughs at Ta, Nb, and Ti, and peaks at Pb, which are found in both Plio-Quaternary calc-alkaline rocks of the Balkan and Italian regions. However, Sr, Nd, and Pb isotope ratios differ significantly from Balkan calc-alkaline volcanic rocks, whereas they are within the range of the Early Pleistocene Campanian Plain buried volcanism (Fig. 4b). Based on both major-trace element composition, isotope data and the chronological setting of the San Nicandro Formation, the Early Pleistocene calc-alkaline volcanism of the Neapolitan-Campanian area can be thus regarded as the most likely source for San Nicandro tephra. Ongoing analyses, consisting in a multidisciplinary approach that integrates sedimentology, micropaleontology, palynology, tephrochronology, geochemistry and magnetostratigraphy, will constrain the onset and subsequent evolution of the San Nicandro lacustrine system, unraveling the late Pliocene-early Pleistocene climatic variations in the central Mediterranean area and bringing new insights on the post-orogenic evolution of the central Apennines.