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Results of high-resolution integrated stratigraphic studies (calcareous plankton and magnetostratigraphy) of three Mediterranean sections (La Vedova in Central Italy, Contrada Pesciarello in Sicily and St. Peter’s Pool in Malta) and one deep-sea core from the mid-latitude North Atlantic (DSDP Hole 608) are here synthesized. They are compared with those of previously studied deep marine sections in the Mediterranean including the historical stratotype, with the aim to select the most suitable section and criterion to define the Langhian GSSP (Global Stratotype Section and Point). This study significantly improves the existing magnetobiostratigraphic framework for the upper Burdigalian-lower Langhian and opens new perspectives for defining the Langhian GSSP. An extensive review of the first stages of the Globigerinoides-Praeorbulina evolutionary lineage pointed out that the Praeorbulina datum, historically used (and/or suggested) to approximate the base of the Langhian, coincides with the First Occurrence (FO) of P. glomerosa curva instead of P. sicana which is here included in the genus Globigerinoides. The FO of P. glomerosa curva occurs close to the C5Br/C5Bn.2n reversal boundary. As a consequence, the two recommended guiding criteria to recognize the base of the Langhian, i.e. the Praeorbulina datum and the top of Chron C5Cn.1n, can not be applied together, as these two events differ in age by ~740 kyr. The selection of either of these two criteria will imply a different duration for the Langhian: relatively short, in case the FO of P. glomerosa curva is selected, or longer and probably more acceptable, in case the top of Chron C5Cn.1n is selected. The primary calcareous plankton biohorizons which, according to our data, appoximate the top of Chron C5Cn.1n, are the Last Common Occurrence (LCO) of the calcareous nannofossil Helicosphaera ampliaperta and the LCO of the planktonic foraminifer Paragloborotalia bella. Other calcareous plankton events have been recorded close to the same magnetic reversal, such as a short influx of H. ampliaperta (Ia1) and the Paragloborotalia siakensis Acme0. The P. siakensis Acmea End (AaE) and the Sphenolithus heteromorphus Paracme End (PE) represent the primary plankton biohorizons associated with the P. glomerosa curva FO. Two of the three studied Mediterranean sections (La Vedova and St. Peter’s Pool), each from different point of view, are potentially suitable to be proposed as candidates for the definition of the Langhian GSSP. Yet, further studies on stable isotope stratigraphy and cyclostratigraphy, including astronomical tuning are necessary before the most suitable section and guiding criterion can be selected.

Results of high-resolution integrated stratigraphic studies (calcareous plankton and magnetostratigraphy) of three Mediterranean sections (La Vedova in Central Italy, Contrada Pesciarello in Sicily and St. Peter's Pool in Malta) and one deep-sea core from the mid-latitude North Atlantic (DSDP Hole 608) are here synthesized. They are compared with those of previously studied deep marine sections in the Mediterranean including the historical stratotype, with the aim to select the most suitable section and criterion to define the Langhian GSSP (Global Stratotype Section and Point). This study significantly improves the existing magnetobiostratigraphic framework for the upper Burdigalian-lower Langhian and opens new perspectives for defining the Langhian GSSP. An extensive review of the first stages of the Globigerinoides-Praeorbulina evolutionary lineage pointed out that the Praeorbulina datum, historically used (and/or suggested) to approximate the base of the Langhian, coincides with the First Occurrence (FO) of P. glomerosa curva instead of P. sicana which is here included in the genus Globigerinoides. The FO of P. glomerosa curva occurs close to the C5Br/C5Bn.2n reversal boundary. As a consequence, the two recommended guiding criteria to recognize the base of the Langhian, i.e. the Praeorbulina datum and the top of Chron C5Cn.1n, can not be applied together, as these two events differ in age by ~740 kyr. The selection of either of these two criteria will imply a different duration for the Langhian: relatively short, in case the FO of P. glomerosa curva is selected, or longer and probably more acceptable, in case the top of Chron C5Cn.1n is selected. The primary calcareous plankton biohorizons which, according to our data, appoximate the top of Chron C5Cn.1n, are the Last Common Occurrence (LCO) of the calcareous nannofossil Helicosphaera ampliaperta and the LCO of the planktonic foraminifer Paragloborotalia bella. Other calcareous plankton events have been recorded close to the same magnetic reversal, such as a short influx of H. ampliaperta (Ia1) and the Paragloborotalia siakensis Acme 0. The P. siakensis Acme a End (AE) and the Sphenolithus heteromorphus Paracme End (PE) represent the primary plankton biohorizons associated with the P. glomerosa curva FO. Two of the three studied Mediterranean sections (La Vedova and St. Peter's Pool), each from different point of view, are potentially suitable to be proposed as candidates for the definition of the Langhian GSSP. Yet, further studies on stable isotope stratigraphy and cyclostratigraphy, including astronomical tuning are necessary before the most suitable section and guiding criterion can be selected.

High-resolution quantitative and qualitative analyses of the planktonic foraminifer and calcareous nannofossil content have been carried out on three Middle Miocene sections, from the Mediterranean area. Such sections (Cretaccio section, Tremiti Islands, Southern Italy; Moria section, Marche Region, Central Italy; DSDP Site 372 succession, Balearic Basin), all well known in the literature, have been chosen because of their high-quality biostratigraphic potential. Remarkable magnetostratigraphic data were provided by the Site 372 succession where all chrons and subchrons of the interval C5Br-C5AAn have been recognised. The investigated interval falls between the First Occurrence (FO) of Praeorbulina glomerosa sicana and the Last Occurrence (LO) of Sphenolithus heteromorphus and Globorotalia peripheroronda. The LO of S. heteromorphus was detected in the uppermost part of the investigated sequence of Site 372 at the same stratigraphic level of the G. peripheroronda LO. A drastic decrease in abundance of S. heteromorphus (Last Common Occurrence -LCO) was detected slightly below its last occurrence; this event is well correlatable with the same event astronomically calibrated at Ras-il Pellegrin section (Malta Island), which has been recently ratified as the Global Stratotype Section and Point (GSSP) for the base of the Serravallian by the International Union of Geological Sciences. The stratigraphic correlation of the studied sections is based on first and last occurrences, abundance fluctuations of selected taxa and additional biohorizons. In particular the peculiar distribution pattern of some taxa, e.g. Paragloborotalia siakensis and Helicosphaera waltrans, offered the opportunity to increase the biostratigraphic resolution of the Langhian interval. The resulting integrated calcareous plankton bio-magnetostratigraphic scheme represents the downward extension of that one previously established for the Serravallian-Tortonian interval. The biostratigraphic correlation of the studied sections with the Langhian historical Stratotype pointed out its low degree of reliability. On the other hand, none of the sections here studied is suitable to be proposed as candidate for defining the Langhian GSSP. Thus the problem of finding, in the Mediterranean area, a valid section which could yield a new GSSP for the Langhian Stage is still open., Rivista italiana di Paleontologia e Stratigrafia, Vol 114, No 1

The relative position of 30 main bioevents pertaining to calcareous nannofossils and planktonic foraminifera was identified in the time interval between 13.75 Ma and 10.50 Ma, based on the quantitative study of the those microfossils in three Mediterranean sections spanning the late Langhian – lower Tortonian stratigraphic interval. The events were correlated to the astronomic target curve using a cyclostratigraphic approach, resulting in a very detailed biostratigraphic and biochronologic subdivision of the interval. The zonal scheme proposed by Fornaciari et al. (1996) was adopted for the calcareous nannofossils, but three subzones were identified in the MMN7 Zone. For the planktonic foraminifera reference is made to the zonal scheme recently proposed by Foresi et al. (1998), slightly modified in order to increase its biostratigraphic resolution. The age of all the zonal boundaries is reported., Rivista italiana di Paleontologia e Stratigrafia, Vol 108, No 2

The planktonic foraminifer and calcareous nannofossil content of two Middle Miocene sections of the Tremiti Islands (Southern Adriatic Sea) have been studied. The two sections are composed of marly limestones rich in calcareous plankton which show cyclic alternations of indurated (higher carbonate content) whitish and less indurated grey or reddish beds. The two sections represent a succession with a total thickness of 38 m. Samples have been collected at a mean spacing of 10-15 cm; qualitative analyses were performed on one sample per meter but quantitative analyses were made for each sample. The abundance fluctuations of several marker species proved to be a very useful tool to correlate the two sections. The astronomical calibration of the sedimentary cycles provided absolute ages for all the recognised calcareous plankton bioevents., Rivista italiana di Paleontologia e Stratigrafia, Vol 108, No 2