The distribution pattern of Helicosphaera inversa (Gartner) Theodoridis is examined from a mid-latitude North Atlantic core (MD01-2446) and two Mediterranean cores (Ocean Drilling Program-ODP Site 975 and Core KC01B) throughMarine Isotope Stage (MIS) 13 to 9. The earliest rare occurrences are observed from the uppermost part of MIS 12, while common and continuous abundances characterize MIS 11. The paleoenvironmental framework of the study cores suggests that the taxon thrived in warm surface waters. Correlation with new data fromplanktonic foraminifera also suggests that H. inversa may have only flourishedwithin a limited salinity range. Comparison with previous findings highlights major diachrony in the FO of the taxon between low and mid-latitude records. It first occurred at lower latitude in the Pacific as early as 0.8 Ma, while in the mid-latitude North Atlantic regions, it is not recorded before 0.51 Ma. The distribution of the taxon in the North Atlantic Ocean also apparently varies in relation with surface water masses and hydrographic fronts. The results suggest that the FO of H. inversa is ecologically controlled and needs to be used with caution in worldwide stratigraphic correlation.Nevertheless, the distribution of the specieswithin theMediterranean Basin can produce an invaluable ecostratigraphical signal.

Geomagnetic dipole moment (GDM) lows associated with polarity reversals or geomagnetic excursions induce significant modulation of the cosmogenic nuclide Beryllium-10 (10Be) production. Hence, the reconstruction of atmospheric 10Be production rates from natural archives such as marine sedimentary sequences or ice cores constitutes a complementary approach, independent from paleomagnetic measurements, to decipher past GDM fluctuations. This is particularly important in the Montalbano Jonico succession (South Italy) since it is candidate to host the Global Stratotype Section and Point of the Middle Pleistocene Stage but where the magnetostratigraphic positioning of the Matuyama–Brunhes boundary (MBB) has not been available up to now. This study presents (1) original authigenic 10Be cosmogenic nuclide and 9Be stable isotope results, and (2) new high-resolution benthic oxygen isotope record covering termination IX and Marine Isotope Stage (MIS) 19. A robust chronological framework is established on the basis of (i) our oxygen isotope stratigraphy, using the strong analogies between MIS 1 and MIS 19c in terms of orbital forcing and CO2level, and (ii) one precise 40Ar/39Ar date obtained in the tephra layer V4. The authigenic 10Be/9Be ratio record marks the atmospheric 10Be overproduction linked to the dipole low accompanying the MBB transition, with a characteristic twofold increase of the 10Be production at the end of MIS 19c and early MIS 19b. This signature is similar to those described in both marine and ice core records. The detailed chronostratigraphy constrained by a radiometrically-dated tephra layer (773.9 ±1.3ka) within the MBB interval, makesit possible to discuss the structure and to assess the timing of the 10Be-production changes, and thus the MBB geomagnetic variations, with an unprecedented accuracy for a marine archive (sedimentation rates ∼80cm/ka). These new cosmogenic nuclide production signatures provide the only missing constraint required for retaining the Montalbano Jonico succession as a global-scale correlation reference section for the Early–Middle Pleistocene boundary.

The paleoenvironmental conditions through MIS 15-9 at the Mediterranean Ocean Drilling Program (ODP) Site 975 were interpreted by high resolution study of calcareous plankton assemblages compared with available δ18O and δ13C records and high resolution paleoclimate proxies from the Atlantic Ocean. Sea Surface Temperatures (SSTs) have been estimated fromplanktonic foraminiferal assemblages using the artificial neural networks method. Calcareous plankton varied dominantly on a glacial–interglacial scale as testified by the SST record, foraminiferal diversity, total coccolith abundance and changes in warm-water calcareous nannofossil taxa. A general increase in foraminiferal diversity and of total coccolith abundance is observed during interglacials.Warmest SSTs are reached during MIS 11, while MIS 12 and MIS 10 represent the coldest intervals of the studied record. During MIS 12, one of the most extreme glacials of the last million years, occurrence of Globorotalia inflata and of neogloboquadrinids indicates a shoaling of the interface between Atlantic inflowing and Mediterranean outflowing waters. Among calcareous nannofossils the distribution of Gephyrocapsa margereli–Gephyrocapsa muellerae N 4 μm also supports a reduced Atlantic–Mediterranean exchange during MIS 12. Superimposed on glacial–interglacial variability, six short-term coolings are recognized during MIS 12 and 10, which appear comparable in their distribution and amplitude to the Heinrich-type events documented in the Atlantic Ocean in the same interval. During these H-type events, Neogloboquadrina pachyderma (s) and G. margereli– G.muellerae N 4 μmincrease as a response to the enhanced inflow of cold Atlanticwater into theMediterranean via the Strait of Gibraltar. Mediterranean surfacewater hydrography appears to have beenmost severely affected at Termination V during the H-type event Ht4, possibly as a response to a large volume of Atlantic meltwater inflow via the Strait of Gibraltar and/or to freshwater/terrigenous input deriving from local mountain glaciers. Three additional SST coolings are recorded through MIS 14–16, but these are not well correlated with Heinrich-type events documented in the Atlantic Ocean in the same interval; during these cooling episodes only the subpolar Turborotalita quinqueloba increases. These results highlight the sensitive response of the Mediterranean basin to millennial-scale climate variations related to Northern Hemisphere ice-sheet instability and support the hypothesis that the tight connection between high latitude climate dynamics andMediterranean sea surface water features can be traced through the Middle Pleistocene.

Coccolithophore assemblages have been investigated at Integrated Ocean Drilling Program Site U1385, on the western Iberian margin, through Marine Isotope Stage (MIS) 16 to 10, between the end of the Mid-Pleistocene Transition and the Mid-Brunhes interval, with the aim to reconstruct orbital and millennial-scale surface water modifications. Assemblage variations are interpreted in terms of paleoclimate and paleoproductivity proxies. The pattern of C37 alkenones is also presented as an additional indicator of primary paleoproductivity. The overall proxies are compared with the available benthic and planktonic δ18O records and Ca/Ti profile. A newbenthic and planktonic δ13C dataset is also shown. The coccolithophore abundance mirrors the Ca/Ti pattern indicating that coccolith-derived carbonate is the dominant contributor to carbonate production in the studied interval. The distinct increase in the coccolithophore abundance, as well as in the accumulation rate, occurring at the MIS 14/13 transition, reflects the beginning of the worldwide-scale mid-Brunhes blooming of Gephyrocapsa caribbeanica and triggers the increase in carbonate production imprinted on the Ca/Ti profile. Interglacials are marked by enhanced abundances of the coccolithophore warm water group (wwt group) that also displays high frequency variability related to precessional/insolation forcing. Warmest surface water conditions are recorded during MIS 15, suggesting an intensified contribution of the subtropical AzC, essentially during MIS 15.5 and 15.1. Reduced productivity in these intervals is in agreement with a major influence of nutrient-poor and less ventilated subtropical waters. On the other hand, productive and mixed surface water conditions can be inferred during MIS 13 in agreement with other North Atlantic records. A long lasting period of warm, stratified and oligotrophic waters is inferred during MIS 11.3, indicating a continuous and more persistent influence of subtropical waters at the site location. Glacial phases are marked by increases of Coccolithus pelagicus ssp. pelagicus and of Gephyrocapsa margereli–Gephyrocapsa muellerae. The pattern of C. pelagicus ssp. pelagicus during MIS 16 is in agreement with a southern position of the Polar Front at the end of the Mid-Pleistocene Transition with respect to younger counterparts, whereas the pattern of the wwt group during MIS 14 attests the influence of subtropical water during this weak glacial. Throughout the interval, short-lived increases of C. pelagicus ssp. pelagicus, G. margereli–G. muellerae N 4 μm and of reworked taxa are concomitant to decreases of coccolithophore productivity and heavier values of planktonic δ18O, testifying the occurrence of abrupt cold episodes related to North Hemisphere millennial-scale climate oscillations.

Integrated high resolution data from calcareous plankton assemblages (foraminifera and nannofossils) together with geochemical and mineralogical investigations have been collected at the on-land Montalbano Jonico section (southern Italy) in order to reconstruct the paleoenvironmental changes through Marine Isotope Stages (MIS) 23–37. Time-series analysis on Globigerina bulloides and Cassidulina carinata δ18O records and on selected calcareous plankton proxies mainly revealed the occurrence of precession and obliquity forcing. The deposition of sapropel layers, which are interbedded in the Montalbano Jonico section, was driven by water column stratification (insolation cycle i-104) and enhanced sea surface water productivity (insolation cycle i-112, i-102 and i-86). Different paleoenvironmental conditions mark the sedimentary evolution of the section. From 1240 to 1082 ka (MIS 37–MIS 32), high percentage abundances of warm and oligotrophic planktonic foraminifera and calcareous nannofossil taxa indicate the establishment of oligotrophic and stratified surface water conditions. A key paleoenvironmental change occurred during MIS 31 (from about 1080 to 1065 ka),which was a very warminterglacial characterized by an increase of tropical–subtropical (Globigerinoides ruber group and Globigerinoides trilobus) and low salinity (Braarudosphaera bigelowii) sea surface water taxa. During this interval, more humid climate conditions coupled with changes in local paleomorphology may have triggered a higher and unusual freshwater input and the creation of a new entry point for sediment supply into the basin from a different drainage area. From about 1065 to 1010 ka (MIS 30– MIS 29), a cool and dry climate prevailed in the circum-Mediterranean area during a time of precession maxima. This favored lowered sea surface temperatures and an increase of polar-water Neogloboquadrina pachyderma left coiling. There are also indications of a reduction of the terrigenous input fromthe newsource area. From1010 ka upward (MIS 28–MIS 23), the higher abundances of Globigerina bulloides, Turborotalita quinqueloba and Calciosolenia spp. indicate enhanced productivity conditions probably related to high turbidity of sea surface waters triggered by a more conspicuous sediment input from land. Analysis of the long-term trends in the multiproxy patterns suggests that themajor paleoenvironmental changes occurred as a consequence of the combined effect of orbitally-controlled global climate and regional processes.

Quantitative analyses on calcareous nannofossil assemblages on high temporal resolution (600-800 years) have been carried out from Core KC01B in the Ionian sea (Eastern Mediterranean) throughout Marine Isotope Stage (MIS) 13-9, between 500-300 kiloyears. This is an interval of considerable climate changes known as Mid-Brunhes event, which includes MIS 11, that is considered as a possible analogue for future interglacial conditions. At the Mediterranean core the interval is characterized by the dominance of Gephyrocapsa spp. as also known from ocean records. Calcareous nannofossil abundance fluctuations have been interpreted in terms of modification of sea surface primary productivity/water stratification and temperature. Specifically, increase in abundance of Gephyrocapsa caribbeanica and small Gephyrocapsa coupled with decrease of F. profunda, Syracosphaera spp. and Rhabdosphaera spp. suggests enhanced primary productivity/mixed surface waters during interglacial stages and at the Terminations which can be interpreted in terms of interaction between climate changes and mesoscale oceanographic circulation. On the other hand, distributions of Calciosolenia spp., Oolithotus spp. and Umbilicosphaera sibogae, which are in phase with 18O curve showing higher abundances at the lighter values of the oxygen isotope record,, are considered as warm-water indicators. Biotic proxies point to a peculiar climate dynamics through MIS 12-11 transition (i.e. Termination V). High productive, cool, low salinity and turbid surface waters characterize the early MIS 11 (421-408 ky) and likely reflect enhanced continental humidity/monsoon activity over North Africa and increased runoff into the basin. A late surface water warming with respect to Termination V is established at about 403 ky, during a period of low insolation forcing almost coeval with the deposition of sapropel S11. A climate optimum, lasting about 15 ky (403-389 ky), is then recorded during a period of low insolation forcing centred at 398 ky. The later part of MIS 11 is characterized by climate deterioration at about 389 ky. Comparison with results from subtropical to polar Atlantic records suggests a remarkable relation between Mediterranean and Atlantic climate regime.

The Montalbano Jonico (MJ) section, cropping out in Southern Italy, represents a potential candidate to define the Lower/Middle Pleistocene boundary and it has been proposed as a suitable Global Stratotype Section and Point (GSSP) of the Ionian Stage (Middle Pleistocene). The MJ section is the only continuous benthic and planktonic δ18O on-land reference in the Mediterranean area for the Mid-Pleistocene transition, spanning an interval between about 1240 and 645 ka. Combined biostratigraphy and sapropel chronology, tephra stratigraphy and complete high-resolution benthic and planktonic foraminiferal stable oxygen isotope records already provide a firm chronostratigraphic framework for the MJ section. However, magnetostratigraphy was still required to precisely locate the Brunhes-Matuyama transition and to mark the GSSP for the Ionian stage. We carried out a palaeomagnetic study of a subsection (Ideale section) of the MJ composite section, sampling 61 oriented cores from 56 stratigraphic levels spread over a ca. 80-m-thick stratigraphic interval that correlates to the oxygen isotopic stage 19 and should therefore include the Brunhes-Matuyama reversal. The palaeomagnetic data indicate a stable and almost single-component natural remanent magnetization (NRM).Acharacteristic remanent magnetization (ChRM)was clearly identified by stepwise demagnetization of the NRM. The ChRM declination values vary around 0◦ and the ChRM inclination around the expected value (59◦) for a geocentric axial dipole field at the sampling locality. This result indicates that the section has been remagnetized during the Brunhes Chron. A preliminary study of 27 additional not azimuthally oriented hand samples, collected at various levels from other parts of the MJ composite section, indicates that all the samples are of normal polarity and demonstrates that the remagnetization is widespread across the whole exposed stratigraphic sequence. A series of specific rock magnetic techniques were then applied to investigate the nature of the main magnetic carrier in the study sediments, and they suggest that the main magnetic mineral in the MJ section is the iron sulphide greigite (Fe3S4). Scanning electron microscope observations and elemental microanalysis reveal that greigite occurs both as individual euhedral crystals and in iron sulphides aggregates filling voids in the clay matrix. Therefore, we infer that the remagnetization of the section is due to the late-diagenetic growth of greigite under reducing conditions,most likely resulting in the almost complete dissolution of the original magnetic minerals. Iron sulphide formation in the MJ section can be linked to migration of mineralized fluids. Our inferred timing of the remagnetization associated with greigite growth represents the longest remanence acquisition delay documented in greigite-bearing clays of the Italian peninsula so far.

A unique composite record from the Mediterranean area exposed on land and spanning the entire time interval of the Calabrian Stage is presented. The record is composed of the Vrica-Crotone section (Calabria, southern Italy) and the Montalbano Jonico section (Basilicata, southern Italy). The Vrica-Crotone section contains the proposed Global Stratotype Section and Point (GSSP) of the Calabrian Stage and extends from Marine Isotope Stage (MIS) 65 to 37 for its Calabrian portion. The Montalbano Jonico section extends from MIS 37 to 17-16. Its upper portion contains MIS 19, which is known to occur close to the Matuyama/Brunhes reversal, and may represent a suitable horizon for the definition of the GSSP of the ‘Ionian’ Stage. Both sections are astronomically tuned, thus providing accurate ages for the bioevents. New biostratigraphic results and radiometric data on volcaniclastic layer V3 of the Montalbano Jonico section are presented together with an updated tuning of the section. A comparison with several Mediterranean and north Atlantic deepsea cores is also shown to verify the consistency and reliability of the biostratigraphic data. The Vrica-Crotone and Montalbano Jonico sections can be considered a suitable composite record for the Calabrian unitstratotype and support the revaluation of the unitstratotype concept in addition to the GSSP approach.