Patrizia Maiorano

Integrated stratigraphy of the Oligocene pelagic sequence in the Umbria-Marche basin (northeastern Apennines, Italy): A potential Global Stratotype Section and Point (GSSP) for the Rupelian/Chattian boundary

The Oligocene represents an important time period from a wide range of perspectives and includes significant climatic and eustatic variations. The pelagic succession of the Umbria-Marche Apennines (central Italy) includes a complete and continuous sequence of marly limestones and marls, with volcaniclastic layers that enable us to construct an integrated stratigraphic framework for this time period. We present here a synthesis of detailed biostratigraphic, magnetostratigraphic, and chemostratigraphic studies, along with geochronologic results from several biotite-rich volcaniclastic layers, which provide the means for an accurate and precise radiometric calibration of the Oligocene time scale. From this study, the interpolated ages for the Rupelian/Chattian stage boundary, located in the upper half of Chron 10n at meter level 188 in the Monte Cagnero section, and corresponding to the O4/O5 planktonic foraminiferal zonal boundary, are 28.36 Ma (paleomagnetic interpolation), 28.27 ± 0.1 Ma (direct radioisotopic dating), and 27.99 Ma (astrochronological interpolation). These ages appear to be slightly younger than those reported in recent chronostratigraphic time scale compilations. The Monte Cagnero section is a potential candidate for defining the Chattian Global Stratotype Section and Point (GSSP) and some reliable criteria are here proposed for marking the Rupelian/Chattian boundary according to International Union of Geological Sciences (IUGS) recommendations.

CALCAREOUS NANNOFOSSIL EVENTS IN THE LOWER-MIDDLE PLEISTOCENE TRANSITION AT THE MONTALBANO JONICO SECTION AND ODP SITE 964: CALIBRATION WITH ISOTOPE AND SAPROPEL STRATIGRAPHY

We present quantitative data on calcareous nannofossil biostratigraphy in the section of Montalbano Jonico (Southern Italy). This is one of the candidate Global Statotype Section and Point (GSSP) of the Middle Pleistocene. The first common occurrence (FCO) and last common occurrence (LCO) of Reticulofenestra asanoi are well detectable in the section and are here proposed as additional events for improving biostratigraphic resolution in the interval corresponding to the transition between the small Gephyrocapsa Zone and Pseudoemiliania lacunosa Zone. The potential value of the bioevents is tested in a Mediterranean deep-sea core of ODP Site 964, located in the Ionian Sea. At Site 964 the FCO of R. asanoi occurs in the marine oxygen isotope stage (MIS) 30, and the LCO of the species correlates with MIS 23. The ages of the FCO and LCO of R. asanoi have been estimated at 1.06 Ma and 0.93 Ma respectively. The first occurrence (FO) of Gephyrocapsa sp. 3 has been correlated to MIS 25, both at Site 964 and at the Montalbano Jonico section. The age of the FO of Gephyrocapsa sp. 3 is estimated at 0.95 Ma, based on the astronomical datings of sapropels occurring at the Montalbano Jonico section. In addition, an interval of temporary disappearance of Gephyrocapsa sp. 3 has been identified within the P. lacunosa Zone. The beginning of this interval is correlated with MIS 20/19 and can be considered a reliable event in the Mediterranean area, occurring close to the Brunhes/Matuyama magnetic boundary. The recognized events provide a basis for interpreting the Montalbano Jonico section within a standard chronostratigraphic framework.

Coccolithophores as proxy of seawater changes at orbital-to-millennial scale during middle Pleistocene Marine Isotope Stages 14–9 in North Atlantic core MD01-2446

Quantitative coccolithophore analyses were performed in core MD01-2446, located in the midlatitude North Atlantic, to reconstruct climatically induced sea surface water conditions throughout Marine Isotope Stages (MIS) 14–9. The data are compared to new and available paleoenvironmental proxies from the same site as well as other nearby North Atlantic records that support the coccolithophore signature at glacial-interglacial to millennial climate scale. Total coccolithophore absolute abundance increases during interglacials but abruptly drops during the colder glacial phases and deglaciations. Coccolithophore warm water taxa (wwt) indicate that MIS11c and MIS9e experienced warmer and more stable conditions throughout the whole photic zone compared to MIS13. MIS11 was a long-lasting warmer and stable interglacial characterized by a climate optimum during MIS11c when a more prominent influence of the subtropical front at the site is inferred. The wwt pattern also suggests distinct interstadial and stadial events lasting about 4–10 kyr. The glacial increases of Gephyrocapsa margereli-G. muellerae 3–4 µm along with higher values of Corg, additionally supported by the total alkenone abundance at Site U1313, indicate more productive surface waters, likely reflecting the migration of the polar front into the midlatitude North Atlantic. Distinctive peaks of G. margereli-muellerae (>4 µm), C. pelagicus pelagicus, Neogloboquadrina pachyderma left coiling, and reworked nannofossils, combined with minima in total nannofossil accumulation rate, are tracers of Heinrich-type events during MIS12 and MIS10. Additional Heinrich-type events are suggested during MIS12 and MIS14 based on biotic proxies, and we discuss possible iceberg sources at these times. Our results improve the understanding of mid-Brunhes paleoclimate and the impact on phytoplankton diversity in the midlatitude North Atlantic region.

Revised correlations of Early and Middle Miocene calcareous nannofossil events and magnetostratigraphy from DSDP Site 563 (North Atlantic Ocean)

Abstract Deep Sea Drilling Project Site 563, located on the west flank of the northern Mid-Atlantic Ridge, recovered a long Miocene section from which magnetostratigraphic and isotopic stratigraphy are available. Quantitative analyses of calcareous nannofossil assemblages have been performed in the Lower and Middle Miocene sediments from Site 563. The abundance patterns of the identified species allow us to determine several bioevents for this time interval. The recognized biohorizons, related to the available magnetostratigraphy, provide new data on the biostratigraphic value of many species and on the synchroneity of the events over a wide geographic area. Relations with the oxygen isotope stratigraphy are also reported. Sphenolith distribution is examined in particular detail due to their biostratigraphic importance in the Early Miocene. In particular the recently described species Sphenolithus procerus , Sphenolithus tintinnabulum and Sphenolithus multispinatus can be useful to subdivide the Lower Miocene zones NN2 and NN3. A large variety of Reticulofenestra pseudoumbilicus has been identified within zones NN6 and NN7.

EARLY TO LATE OLIGOCENE CALCAREOUS NANNOFOSSIL BIOEVENTS IN THE MEDITERRANEAN (UMBRIA-MARCHE BASIN, CENTRAL ITALY)

Calcareous nannofossil assemblages have been investigated by means of quantitative analyses in three Oligocene pelagic sections located in the Umbria-Marche Apennines (Central Italy). The studied sections mainly consist of marly limestones and marls belonging to the Scaglia Cinerea Formation, and include the interval between NP23 and NP25 representing a time interval of about 3.5 Ma. Biostratigraphic resolution is extremely low and only two standard bioevents are known, which are the FO of Sphenolithus ciperoensis and the LO of Sphenolithus distentus . The distribution patterns of poorly known or recently described calcareous nannofossils provided a valuable tool for improving the current biostratigraphic framework. The studied interval is characterized by significant changes in the calcareous nannofossil assemblages and by several extinction events. The last occurrence (LO) and/or the last common occurrence (LCO) here proposed are: the LO of Sphenolithus akropodus , the LO of Reticulofenestra circus , the LCO of Helicosphaera ethologa , the LCO of Helicosphaera compacta the LO of Discoaster tanii nodifer . The reversal in abundance between Sphenolithus predistentus and S. distentus provided an additional biostratigraphic constraint at the NP23-NP24 transition. In addition biometric criteria enabled the recognition of the first common occurrence (FCO) of Cyclicargolithus abisectus > 12 mm as potential bioevent within NP24. The quantitative distribution of Sphenolithus distentus suggests to rely on the LCO of the species rather than on the LO, for the identification of NP24-NP25 boundary. The identified bioevents is a first step towards the improvement of the present Mediterranean biostratigraphic framework of the Oligocene geological record. A preliminary correlation of the bioevents to the Geomagnetic Polarity Time Scale is presented.

MIOCENE QUANTITATIVE CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY FROM SOUTHERN APENNINES FOREDEEP DEPOSITS AND MEDITERRANEAN DSDP SITE 372

A quantitative biostratigraphic study based on calcareous nannofossil assemblages was carried out in nine Miocene calcareous and siliciclastic foredeep sections, cropping out in the outer part of the Southern Apennines and generally ascribed to the external Irpinian units. Several biozonal events were recognised by means of quantitative analyses, according to the biostratigraphic schemes of Fornaciari & Rio (1996) and Fornaciari et al. (1996) for the lower and middle Miocene and of Theodoridis (1984) for the upper Miocene. In the lower and middle Miocene interval some biohorizons such as the first common occurrence of Helicosphaera walbersdorfensis and last common occurrence of Calcidiscus premacintyrei are not always detectable in the studied sections and the first common occurrence of Calcidiscus macintyrei appears to be a better biohorizon in the MNN6b/7 than the last common occurrence of C. premacintyrei . New data on abundance patterns of selected calcareous nannofossils have been collected, thus improving the biostratigraphic resolution of the zonal schemes: a paracme interval of small Reticulofenestra pseudoumbilicus was noted within Zone MNN4b and MNN5a; the beginning and the end of the paracme are useful events in the studied sections for stratigraphic correlations. Moreover the occurrence of R. pseudoumbilicus has been recorded from Zone MNN2b on upwards, fairly below the FCO of the species that defines the base of Zone MNN6b. The distributions observed in the on-land sections are consistent with those recognised in DSDP Site 372 located in the western Mediterranean Sea, confirming their potential biostratigraphic utility within the Mediterranean region.

Revised stratigraphy of the Serra Palazzo Formation, a Miocene foredeep turbidite succession of the Southern Apennines (Italy)

This paper illustrates a new structural and stratigraphical framework of the Serra Palazzo Formation which represents a Miocene turbidite succession cropping out at the outer border of the Southern Apennines. The study has been performed in the type area of the Serra Palazzo Formation, in the neighbourhood of Stigliano village (Basilicata, Southern Italy). Structural evidence allowed to recognise that in the study area the Serra Palazzo Formation has been splitted in different east verging thrust sheets whose decollement level is localized in the upper part of the Flysch Rosso Formation. The stratigraphical features of the study formation have been collected in two sections (S1 and S2) belonging to two superimposed thrust sheets; biostratigraphic analyses have been performed by means of quantitative methods on the calcareous nannofossil assemblages. The obtained results indicate that in the type area the Serra Palazzo Formation is about 500 m thick and from the bottom to the top consists of: a lower coarse grained siliciclastic turbidite unit (Tempa Cisterna Member), which lies stratigraphically on the Flysch Numidico Formation and is Burdigalian-Langhian in age; an upper siliciclastic and calciclastic fine grained turbidite unit (Jazzo Porcellini Member) that is Serravallian in age. The Jazzo Porcellini Member passes upward into the Marne argillose del Toppo Capuana Formation, of Serravallian-Tortonian age. The Tempa Cisterna Member, which has a north western feeding, reaches its maximun thickness (350 m) in the inner thrust sheet; on the contrary, the Jazzo Porcellini Member shows evidence of a consistent eastern supply and has its maximun thickness (250 m) in the outer thrust sheet. Preliminary studies suggest that the stratigraphical framework of the Serra Palazzo Formation as reconstructed in the study area can be also recognised in other areas of the Southern Apennines; these evidences provide new data on the evolution of the Southern Apennines Miocene foredeep.

Geological map of the eastern sector of the Gorgoglione Basin (southern Italy)

In this paper we report new stratigraphic data related to a new geological map of the Miocene Gorgoglione Basin of southern Italy, traditionally considered as a piggy-back or wedge-top basin filled by a turbidite-like succession. Well exposed outcrops in the study area (eastern sector of the basin) show four unconformities in the Castelmezzano-Pietrapertosa area. Two of these unconformities pass to paraconformities southeastward, in the Cirigliano-Gorgoglione area. Based on new stratigraphic data the succession of the Gorgoglione Flysch can be divided into different informal units: Val Miletta formation and Gorgoglione supersynthem. The latter can be subdivided into the Cirigliano and Castelmezzano synthems. The previously established Cirigliano synthem is here divided into three subsynthems. The lowermost sediments of the Gorgoglione Flysch on the eastern sectors correspond to a complex unit (Val Miletta formation) including Numidian-like quartzarenites, Gorgoglionelike sandstones, and, at the top of the formation, an olistostrome of varicoloured clays, belonging to the Argille Variegate Group. The stratigraphic analyses and the biostratigraphic results based on calcareous plankton assemblage, improve the reconstruction of the geometries of the sedimentary bodies and the time-space facies evolution of the synthems. Sedimentologic and petrographic characters of the upper part of the Castelmezzano synthem show a clear fining and thinning upward trend. Medium- and fine-grained arenites, varying in composition from quartz sandstones to siltstones and shales, are locally marked by abundant planktonic foraminifera and are interpreted as contourites. Moreover, the relationships between tectonics and sedimentation are analyzed. The data are used to propose a scheme of the Burdigalian to Tortonian tectono-stratigrafiphic evolution of the eastern sector of the basin.

Magmatic and geodynamic significance of two volcaniclastic deposits in the Oligo-Miocene successions of the Southern Apennines (Italy)

Two volcaniclastic deposits, ROC and SBA, in the Oligo-Miocene succession of the Southern Apennines, between the Apulia and Campania regions, have been studied for the first time. Mineral composition, SEM-EDS and LA-ICP-MS analyses, for major and trace elements, respectively, allowed recognizing magmatic products of typical calc-alkaline to high-K calc-alkaline affinity. ROC glasses have a restricted compositional range in the rhyolitic field whereas SBA glasses show a wide compositional range from andesite to rhyolite, with dacite as the most common composition. Fission-track dating of apatite in the SBA deposits yielded an age of 21.7 ± 2.2 Ma, which is comprised between the Chattian and the Burdigalian. Biostratigraphic analyses in sedimentary layers adjacent to ROC layers indicate they were deposited not before Burdigalian. A provenance analysis of the studied volcaniclastics in relation to the possible source areas of the Mediterranean and neighbouring areas was performed. On the basis of time constraints, mineral and trace element composition a convincing correlation of the ROC deposits with potential source areas did not emerge. Instead, a provenance from the southwestern and northwestern Sardinian volcanic centres was favoured for the SBA volcaniclastic deposits. This hypothesis is compatible with the Oligo-Miocene paleogeographic reconstructions, that show the proximity of the Apennine sedimentary basins to Sardinia before the opening of the Tyrrhenian sea.

Climate variability through the Marine isotope Stage 19 in the Bradano Trough (Southern Italy): a multi-proxy record

Abstract from 88th Congress of the Italian Geological Society, 2016-09-07 - 2016-09-09, NaplesAbstract from 88th Congress of the Italian Geological Society, 2016-09-07, 2016-09-09, Naplesbook Edited by D. Calcaterra, S. Mazzoli, F.M. Petti, B. Carmina & A. Zuccari doi: 10.3301/ROL.2016.79