Late Pliocene Middle Pleistocene Research Articles

The Late Pliocene–Middle Pleistocene Large Mammal Faunal Units of Greece

Located at the eastern corner of Mediterranean Europe, Greece occupies a critical position for mammal dispersals to/from Europe, Asia, and Africa and constitutes a potential passageway towards Western Europe. During recent decades, numerous fieldwork campaigns in several Pliocene–Pleistocene sites have greatly enriched the fossil record and provided valuable taxonomic and biostratigraphic data. However, a fully developed reference biochronological unit scheme for the Greek record that could contribute to correlations at a continental scale is still pending. In this article, we provide the updated Late Pliocene to Middle Pleistocene large mammal succession, and we introduce the Faunal Units (FUs) of Greece. We define eight FUs, the Milia, Dafnero, Gerakarou, Tsiotra Vryssi, Krimni, Apollonia, Marathousa, and Apidima FUs (from the oldest to the youngest), which are determined by a set of first and last local occurrences. The results form the basis for discussion of already set turnovers, dispersals, and extinction/immigration events and showcase the importance of the local record for the investigation of the European terrestrial ecosystems. By developing the first detailed biochronological scheme for the Pliocene–Pleistocene of Southeastern Europe, this study comprises the basis for an expanded Balkan faunal unit scale and a reference framework for future investigations.

Characteristics and transition mechanism of late Cenozoic structural deformation within the Niushoushan–Luoshan fault zone at the northeastern margin of the Tibetan Plateau

The Niushoushan–Luoshan fault zone (NLF) separates two major tectonic units: the Ordos Block and the northeastern margin of the Tibetan Plateau. The deformational processes within this fault zone recorded the uplift and expansion of the northeastern margin of the plateau. However, the tectonic transition mechanisms during the end Miocene–Pleistocene, and the characteristics of deformation at the end Pliocene and their tectonic significances, remain unclear. In this study, a detailed survey of structural deformation within the fault zone was carried out. The measurements were combined with regional tectonic analysis and geochronology to determine the effects of changing tectonic stress fields, and proposed the following late Cenozoic tectonic evolution of the NLF: NW–SE compression and left-lateral strike-slip deformation in the late Miocene–Pliocene; NE–SW compression and right-lateral strike-slip movement in late Pliocene–middle Pleistocene; and E–W extensional tectonics since the late Pleistocene. Although the late Miocene deformation indicates that expansion of the northeastern margin of the Tibetan Plateau had already reached this fault zone at this time, the most intense tectonic deformation did not commence until the end of the Pliocene. This indicates that the margin of the plateau was expanding at this time. The results show that the tectonic evolution of the NLF was closely related to collision between the Indian and Eurasian plates, and to uplift of the Tibetan Plateau. The fault zone also records the expansion of the northeastern margin of the Tibetan Plateau and the Cenozoic tectonic transition of the Ordos Block from westward extrusion to clockwise rotation.

Can the morphology of deep-sea benthic foraminifera reveal what caused their extinction during the mid-Pleistocene Climate Transition?

Over 100 cosmopolitan species of deep-sea benthic foraminifera (Extinction Group, Ext. Gp) became extinct during the late Pliocene-middle Pleistocene (3.6–0.55 Ma). Most had elongate, cylindrical tests and terminal apertures with complex modifications. This study provides new hypotheses on the functions of the morphologies that characterised the Ext. Gp and how these features could have been associated with their demise. From our functional morphological analysis we infer that: i) their elongate cylindrical or flabelliform tests, combined with fine perforations and a complex terminal apertural face are indicative of infaunal k-strategists with a low rate of metabolism; and ii) their complex apertural faces may also have been an adaptation for gathering or processing their specific phytodetrital food. We propose three alternative hypotheses for the cause of these extinctions, and where possible test them using our high resolution micropaleontological and geochemical record through the last 1.07 Ma in lower bathyal site MD 97-2114 in the SW Pacific Ocean. Hypothesis 1 is that the Ext. Gp species were unable to adapt to increased variability in the overall quantity or pulsed seasonality of the food supply to the sea floor and were out-competed by opportunistic r-strategist benthic foraminifera. This is supported by the highly variable and increasing abundance of opportunistic foraminifera at our study site during the final phase of the extinction in the mid-Pleistocene Climate Transition, MPT. We doubt however, that there was increased variability in phytoplankton productivity throughout the world's oceans sufficient to bring about the global demise of the Ext. Gp. Hypothesis 2 is that lowered pCO 2 during increasingly severe MPT glacials, which coincided with the final phases of the extinction, may have caused the decline and possible loss of the Ext. Gp's phytoplankton food source. Declining pCO 2 during Neogene cooling was coeval with declining relative abundance of the Ext. Gp and reticulofenestrid nannofossils, but the final demise of this latter phytoplankton group occurred slightly later than the MPT in our study site and cannot be implicated with the extinction. If this hypothesis has any validity maybe the phytoplankton group left no fossil record. Our third alternative hypothesis is that maybe our Ext. Gp had much common DNA which made them the selective target of pathogens that caused their extinction. This does not easily explain their earlier disappearance at abyssal depths than at bathyal depths in our study region, which can be accommodated by hypotheses 1 and 2. • Functional morphology of Extinction group suggests they had low rates of metabolism. • Lowered pCO 2 during MPT glacials caused the decline of reticulofenestrid nannofossils. • Ext. Gp species may have been out-competed by opportunistic benthic foraminifera. • Ext. Gp demise was probably caused by the loss of a particular phytoplankton group particular phytoplankton.

Tectonic and sedimentary evolution of the Upper Valdarno Basin: new insights from the lacustrine S. Barbara Basin

We describe stratigraphic, structural and kinematic data from the sediments of the Upper Pliocene Santa Barbara Basin and from its substratum. The results shed light on the relationships between tectonics and sedimentation in the larger Late Pliocene-Middle Pleistocene Upper Valdarno Basin of which the Santa Barbara Basin is considered a precursor. The sediments filling up the Santa Barbara Basin are made up of alluvial to deltaic and lacustrine deposits,grouped in the Castelnuovo dei Sabbioni (CSB) Synthem, related to Late Pliocene. This synthem was deposited in a tectonic depression reasonably delimited to the East by a west-dipping normal fault system and delimited to the North and to the South by left-lateral transtensional shear zones, which controlled the main directions of the alluvial drainage. During Early Pleistocene, a new master normal fault system (Trappola fault system) developed further to the East, determining the widening of the previous tectonic depression, now delimited to the North and to the South by the regional Piombino-Faenza and Arbia-Val Marecchia transfer zones, respectively. In this new tectonic depression, with a dominant axial drainage direction, alluvial, fluvio-aeolian and fluvial sediments (Montevarchi Synthem, VRC) deposited during Early Pleistocene. The VRC Synthem, being located in the hanging-wall of the Trappola normal fault system, is slightly tilted to the NE. Finally, during Early-Middle Pleistocene, axial fluvial deposits (Torrente Ciuffenna Synthem, UFF), sealed the previously formed brittle structures. Our kinematic and structural data allow us to confirm the interpretation that the Santa Barbara Basin is the precursor of the Upper Valdarno Basin and that both basins developed in structural depressions formed by the interplay between normal and transfer faults, framed in the extensional tectonics which characterizes Tuscany since Miocene.

Rock-magnetic cyclostratigraphy for the Late Pliocene–Early Pleistocene Stirone section, Northern Apennine mountain front, Italy

Abstract Lithostratigraphic, magnetostratigraphic and rock-magnetic cyclostratigraphic data were combined to create a high-resolution age model for 342 m of Late Pliocene–Middle Pleistocene marine deposits exposed in the Stirone River, northern Italy. Magnetostratigraphic analysis of 74 oriented samples at 21 stratigraphic horizons recognized five polarity zones between c. 3.0 and 1.0 Ma. Unoriented samples were collected every metre between 0 and 311 m and low-field magnetic susceptibility ( χ ) was measured for cyclostratigraphic analysis. The χ data series was tied to absolute time using the magnetostratigraphy and subjected to multi-taper method spectral analysis. The resultant power spectra revealed significant frequency peaks that are aligned with eccentricity, obliquity and precession Milankovitch orbital cycles. The χ data, correlated to the 41 ka obliquity and the 23 ka/19 ka precession cycles and anchored to a well-established biostratigraphic horizon, were used to create a high-resolution age model for the Stirone section between 2.99 and 1.81 Ma, where stratigraphic positions of magnetic reversals were previously poorly defined. This cyclostratigraphic age model reveals that the length of an important depositional hiatus at the base of the C2An.1n subchron is 200 ka shorter than previously determined. We link the precession-aligned variability in χ to global mid-latitude, insolation-induced variability in runoff and ocean circulation.

Geochemistry and K-Ar geochronology of the Late Pliocene-Pleistocene volcanism in the southern Andes (39-42°S).

In the Andean Range, south of 39°S, there is a suite of eroded volcanic centres that includes remains of vents or proximal, intermediate or distal volcanic facies. New geochronological K-Ar data show that their ages are in the Late Pliocene-Middle Pleistocene interval, and these eroded centres are equivalent to those located on the eastern side of the Andes. Geochemical patterns of pliocene-pleistocene volcanic centres are similar to those of the Quaternary volcanoes of this segment with a gradual variation toward the east in the La/Sm, Ba/La ratios and K even reaching back-arc signature of the volcanoes far from the trench. Previous works, under the assumption that all volcanic rocks from the western side of the Andes were quaternary in age, have proposed a western migration of the volcanic arc to the west after Pliocene. Instead, our geochronological and geochemical data show that the initial wide Late Pliocene-Middle Pleistocene arc narrows in the Quaternary time preserving the volcanic front. An important variation of the convergence velocity was recognized at the end of Pliocene and the authors propose that it is a first order factor on the geometry and location of the volcanic arc south of the 39°S.

Cenozoic record of elongate, cylindrical, deep-sea benthic foraminifera in the North Atlantic and equatorial Pacific Oceans

In the late Pliocene–middle Pleistocene a group of 95 species of elongate, cylindrical, deep-sea (lower bathyal–abyssal) benthic foraminifera became extinct. This Extinction Group (Ext. Gp), belonging to three families (all the Stilostomellidae and Pleurostomellidae, some of the Nodosariidae), was a major component (20–70%) of deep-sea foraminiferal assemblages in the middle Cenozoic and subsequently declined in abundance and species richness before finally disappearing almost completely during the mid-Pleistocene Climatic Transition (MPT). So what caused these declines and extinction? In this study 127 Ext. Gp species are identified from eight Cenozoic bathyal and abyssal sequences in the North Atlantic and equatorial Pacific Oceans. Most species are long-ranging with 80% originating in the Eocene or earlier. The greatest abundance and diversity of the Ext. Gp was in the warm oceanic conditions of the middle Eocene–early Oligocene. The group was subjected to significant changes in the composition of the faunal dominants and slightly enhanced species turnover during and soon after the rapid Eocene–Oligocene cooling event. Declines in the relative abundance and flux of the Ext. Gp, together with enhanced species loss, occurred during middle–late Miocene cooling, particularly at abyssal sites. The overall number of Ext. Gp species present began declining earlier at mid abyssal depths (in middle Miocene) than at upper abyssal (in late Pliocene–early Pleistocene) and then lower bathyal depths (in MPT). By far the most significant Ext. Gp declines in abundance and species loss occurred during the more severe glacial stages of the late Pliocene–middle Pleistocene. Clearly, the decline and extinction of this group of deep-sea foraminifera was related to the function of their specialized apertures and the stepwise cooling of global climate and deep water. We infer that the apertural modifications may be related to the method of food collection or processing, and that the extinctions may have resulted from the decline or loss of their specific phytoplankton or prokaryote food source, that was more directly impacted than the foraminifera by the cooling temperatures.

Geological, pedological and paleomagnetic study of the late Cenozoic sedimentary sequence in southwestern Uruguay, South America

The results of interdisciplinary studies carried out on the coastal cliffs of southern Uruguay are presented here. The Raigón Formation (late Pliocene–middle Pleistocene) has a cratonic provenance and comprises two sections limited by a regional discontinuity. Each section is composed of an association of lithofacies Ss, Sp, Sr, rare St, and Fm. The last one represents floodplain deposits and the others are interpreted as channel-filled deposits. In the upper part, a well-structured paleosol with clay coatings and abundant rhizoliths is observed in a sharp contact with silty deposits of the Libertad Fm. (early-middle Pleistocene); these sediments have a mixed provenance (magmatic arc and cratonic), sheet-like geometry, thick stratification and vertical walls, and are composed of lithofacies Fr. These characteristics suggest a loessic origin. A paleosol with illuvial B horizons and silty loam texture is recognized at the bottom of this unit. The recent soil (Argiudoll) is developed at the top of the Libertad Fm. The characteristics of the sequence indicate climatic fluctuations and several cycles of erosion, sedimentation and pedogenesis. According to magnetostratigraphy, the chronology is roughly compatible with that one based on the fossil contents and is in agreement with magnetic ages determined in Argentine fossiliferous sequences.

The Early Pliocene re-colonisation of the deep Mediterranean Sea by benthic foraminifera and their pulsed Late Pliocene–Middle Pleistocene decline

Ninety-five species and 19 genera of cosmopolitan, deep-sea benthic foraminifera belonging to the families Pleurostomellidae, Stilostomellidae and Nodosariidae, became extinct during the Late Pliocene–Middle Pleistocene. Only 50% of these (44 species) were present in the Pliocene or Pleistocene of the deep Mediterranean Sea (ODP Sites 654, 966, 967, 975, 976), being those which had successfully migrated in via the Strait of Gibraltar from the deep Atlantic following the annihilation of the Mediterranean deep-sea fauna during the Late Miocene Messinian Crisis. Most colonisation occurred within the first 0.8 myrs (5.3–4.5 Ma) after re-establishment of the Mediterranean–Atlantic link, with possibly a second lesser period of immigration in the Late Pliocene (3.4–3.0 Ma). We infer that colonisations may have been fortuitous and few in number, as some common members of the group in the Atlantic never succeeded in establishing in the Mediterranean Sea. There is no evidence of any new immigration events during the Pleistocene, implying that the present anti-estuarine circulation may have been in place throughout this period. Our studies suggest that these deep-water, low-oxygen-tolerant foraminifera survived the many periods of deep-water sapropel formation in the Pliocene–Early Pleistocene, possibly in somewhat shallower (~ 500 m) refuges with dysoxic, rather than anoxic conditions. The Pliocene–Pleistocene stratigraphic record of this group of elongate, cylindrical benthic foraminifera with constricted and specialised apertures is similar in the west and east Mediterranean basins. The group declined in abundance (flux) and diversity in two pulses, during the Late Pliocene (3.1–2.7 Ma) and the late Early Pleistocene (1.3–1.0 Ma) in concert with global, southern-sourced, deep-water sites (AABW, CPDW) and earlier than the single decline (1.0–0.6 Ma) in global, intermediate water sites (uNADW, AAIW). All species, with one possible exception, disappeared earlier in the Mediterranean than globally. The highest occurrence of any species of this group in Mediterranean sites was 0.8–0.43 Ma, comparable with 0.7–0.2 Ma outside with the youngest survivors being in abyssal, deep-water. Thus, despite the unusual oceanographic conditions and isolation, the deep Mediterranean Sea was in this case neither the centre for the evolution of new species nor a refuge where species survived after they had disappeared elsewhere.

Seismotectonics of strike–slip earthquakes within the deep crust of southern Italy: Geometry, kinematics, stress field and crustal rheology of the Potenza 1990–1991 seismic sequences (M max 5.7)

We present a revision and a seismotectonic interpretation of deep crust strike–slip earthquake sequences that occurred in 1990–1991 in the Southern Apennines (Potenza area). The revision is motivated by: i) the striking similarity to a seismic sequence that occurred in 2002 ∼ 140 km NNW, in an analogous tectonic context (Molise area), suggesting a common seismotectonic environment of regional importance; ii) the close proximity of such deep strike–slip seismicity with shallow extensional seismicity (Apennine area); and iii) the lack of knowledge about the mechanical properties of the crust that might justify the observed crustal seismicity. A comparison between the revised 1990–1991 earthquakes and the 2002 earthquakes, as well as the integration of seismological data with a rheological analysis offer new constraints on the regional seismotectonic context of crustal seismicity in the Southern Apennines. The seismological revision consists of a relocation of the aftershock sequences based on newly constrained velocity models. New focal mechanisms of the aftershocks are computed and the active state of stress is constrained via the use of a stress inversion technique. The relationships among the observed seismicity, the crustal structure of the Southern Apennines, and the rheological layering are analysed along a crustal section crossing southern Italy, by computing geotherms and two-mechanism (brittle frictional vs. ductile plastic strength) rheological profiles. The 1990–1991 seismicity is concentrated in a well-defined depth range (mostly between 15 and 23 km depths). This depth range corresponds to the upper pat of the middle crust underlying the Apulian sedimentary cover, in the footwall of the easternmost Apennine thrust system. The 3D distribution of the aftershocks, the fault kinematics, and the stress inversion indicate the activation of a right-lateral strike–slip fault striking N100°E under a stress field characterized by a sub-horizontal N142°-trending σ1 and a sub-horizontal N232°-trending σ3, very similar to the known stress field of the Gargano seismic zone in the Apulian foreland. The apparent anomalous depths of the earthquakes (> 15 km) and the confinement within a relatively narrow depth range are explained by the crustal rheology, which consists of a strong brittle layer at mid crustal depths sandwiched between two plastic horizons. This articulated rheological stratification is typical of the central part of the Southern Apennine crust, where the Apulian crust is overthrusted by Apennine units. Both the Potenza 1990–1991 and the Molise 2002 seismic sequences can be interpreted to be due to crustal E–W fault zones within the Apulian crust inherited from previous tectonic phases and overthrusted by Apennine units during the Late Pliocene–Middle Pleistocene. The present strike–slip tectonic regime reactivated these fault zones and caused them to move with an uneven mechanical behaviour; brittle seismogenic faulting is confined to the strong brittle part of the middle crust. This strong brittle layer might also act as a stress guide able to laterally transmit the deviatoric stresses responsible for the strike–slip regime in the Apulian crust and may explain the close proximity (nearly overlapping) of the strike–slip and normal faulting regimes in the Southern Apennines. From a methodological point of view, it seems that rather simple two-mechanism rheological profiles, though affected by uncertainties, are still a useful tool for estimating the rheological properties and likely seismogenic behaviour of the crust.

Last global extinction in the deep sea during the mid‐Pleistocene climate transition

Twenty percent (19 genera, 95 species) of cosmopolitan, deep‐sea (500–4000 m), benthic foraminiferal species became extinct during the late Pliocene–Middle Pleistocene (3–0.12 Ma), with the peak of extinctions (76 species) occurring during the mid‐Pleistocene Climate Transition (MPT, 1.2–0.55 Ma). One whole family (Stilostomellidae, 30 species) was wiped out, and a second (Pleurostomellidae, 29 species) was decimated with just one species possibly surviving through to the present. Our studies at 21 deep‐sea core sites show widespread pulsed declines in abundance and diversity of the extinction group species during more extreme glacials, with partial interglacial recoveries. These declines started in the late Pliocene in southern sourced deep water masses (Antarctic Bottom Water, Circumpolar Deep Water) and extending into intermediate waters (Antarctic Intermediate Water, North Atlantic Deep Water) in the MPT, with the youngest declines in sites farthest downstream from high‐latitude source areas for intermediate waters. We infer that the unusual apertural types that were targeted by this extinction period were adaptations for a specific kind of food source and that it was probably the demise of this microbial food that resulted in the foraminiferal extinctions. We hypothesize that it may have been increased cold and oxygenation of the southern sourced deep water masses that impacted on this deep water microbial food source during major late Pliocene and Early Pleistocene glacials when Antarctic ice was substantially expanded. The food source in intermediate water was not impacted until major glacials in the MPT when there were significant expansion of polar sea ice in both hemispheres and major changes in the source areas, temperature, and oxygenation of global intermediate waters.

Extinction of deep-sea foraminifera as a result of Pliocene–Pleistocene deep-sea circulation changes in the South China Sea (ODP Sites 1143 and 1146)

During the Late Pliocene–Middle Pleistocene, 56 species and 15 genera of elongate, cylindrical benthic foraminifera disappeared from the deep sea in the South China Sea (ODP Sites 1143 and 1146) as part of the last global extinction in the deep sea. This extinction group (Ext. Gp) exhibited a pulsed decline in abundance and species richness mostly during glacials, and often associated with periods of expansion of polar ice that resulted from increased cooling of the Earth's climate since ∼2.5 Ma, particularly during the Mid-Pleistocene Climate Transition (MPT, 1.2–0.6 Ma). We infer that the Ext. Gp decline in abundance and disappearance was a result of the increased glacial cooling and consequent increased ventilation of the deep-sea water masses. The detailed record of withdrawal of the Ext. Gp differs between the two sites, with far more disappearances occurring prior to the MPT in the deeper Site 1143 (2772 m) than in the shallower Site 1146 (2092 m). The Late Pliocene and Early Pleistocene declines in deeper parts of the South China Sea (Site 1143) may have resulted from enhanced glacial production of deep, southern-sourced water passing over the sill into the basin from the North-west Pacific. During the MPT however, the Ext. Gp declines and disappearances were of similar timing and magnitude in both sites, implying that both were influenced by the same deep-water mass during glacials at this time. This could have been North Pacific Deep Water, which many workers infer was formed in the northern Pacific during the last glacial, and may have begun forming during MPT glacials, in association with the progressively enhanced cooling of the Northern Hemisphere.

Tectonic and climatic controls on coastal sedimentation: The Late Pliocene–Middle Pleistocene of northeastern Rhodes, Greece

The Late Pliocene to Middle Pleistocene coastal sediments of northeastern Rhodes (Greece) were deposited in an active tectonic setting. They provide an excellent opportunity to investigate the relative roles played by climate and tectonics in sedimentary processes. The tectono-sedimentary organization of these deposits is revised in the light of an integrated study combining data from field investigations, sedimentology, bio- and magnetostratigraphy, radiometric dating, palaeoecology, and palynology. Three lithostratigraphic units are recognised: the Rhodes Formation, the newly defined Ladiko–Tsampika Formation, and the Lindos Acropolis Formation. A major erosional surface separates the Rhodes Formation from the Ladiko–Tsampika Formation, which was deposited in deep and narrow palaeovalleys. The Rhodes Formation (Late Pliocene to 1.4–1.3 Ma) comprises three Members: the Kritika, the Lindos Bay clay and the Cape Arkhangelos calcarenite. The shallow-water clastic sediments of the Ladiko–Tsampika Formation (1.3 to 0.3 Ma) are subdivided into two Members: the Ladiko (mostly sandy) and the Tsampika (predominantly clayey). The Lindos Acropolis Formation is Late Pleistocene in age. Two major transgression–regression cycles occurred prior to the Lindos Acropolis cycle. The deposition of the first cycle (Rhodes Formation) is tectonically controlled, with very high rates of vertical movements (2.6–5.2 mm/year). The second cycle (Ladiko–Tsampika Formation) records sea-level changes controlled by slow vertical motions (around 0.16 mm/year) and glacio-eustatic events with 40-kyr and 100-kyr periods. Finally, the tectonic and sedimentary evolution of Rhodes is integrated into the geodynamic context of the eastern Aegean fore-arc.

Benthic foraminiferal extinctions linked to late Pliocene–Pleistocene deep-sea circulation changes in the northern Indian Ocean (ODP Sites 722 and 758)

During the late Pliocene–middle Pleistocene, 63 species of elongate, bathyal–upper abyssal benthic foraminifera (Extinction Group = Stilostomellidae, Pleurostomellidae, some Nodosariidae) declined in abundance and finally disappeared in the northern Indian Ocean (ODP Sites 722, 758), as part of the global extinction of at least 88 related species at this time. The detailed record of withdrawal of these species differs by depth and geography in the Indian Ocean. In northwest Indian Ocean Site 722 (2045 m), the Extinction Group of 54 species comprised 2–15% of the benthic foraminiferal fauna in the earliest Pleistocene, but declined dramatically during the onset of the mid-Pleistocene Transition (MPT) at 1.2–1.1 Ma, with all but three species disappearing by the end of the MPT (∼0.6 Ma). In northeast Indian Ocean Site 758 (2925 m), the Extinction Group of 44 species comprised 1–5% of the benthic foraminiferal fauna at ∼3.3–2.6 Ma, but declined in abundance and diversity in three steps, at ∼2.5, 1.7, and 1.2 Ma, with all but one species disappearing by the end of the MPT. At both sites there are strong positive correlations between the accumulation rate of the Extinction Group and proxies indicating low-oxygen conditions with a high organic carbon input. In both sites, there was a pulsed decline in Extinction Group abundance and species richness, especially in glacial periods, with some partial recoveries in interglacials. We infer that the glacial declines at the deeper Site 758 were a result of increased production of colder, well-ventilated Antarctic Bottom Water (AABW), particularly in the late Pliocene and during the MPT. The Extinction Group at shallower water depths (Site 722) were not impacted by the deeper water mass changes until the onset of the MPT, when cold, well-ventilated Glacial North Atlantic Intermediate Water (GNAIW) production increased and may have spread into the Indian Ocean. Increased chemical ventilation at various water depths since late Pliocene, particularly in glacial periods, possibly in association with decreased or more fluctuating organic carbon flux, might be responsible for the pulsed global decline and extinction of this rather specialised group of benthic foraminifera.

A latest Biharian small vertebrate fauna from the lacustrine succession of San Lorenzo (Sant’Arcangelo Basin, Basilicata, Italy)

The Sant’Arcangelo Basin is located in the southern part of the Apennine chain (Basilicata). It is filled by a siliciclastic sequence 3500 m thick, dated to the Late Pliocene–Middle Pleistocene time interval. In this basin an Early Middle Pleistocene fluvio-lacustrine sequence, known as San Lorenzo Cycle, has been recognised. In the upper part of the sequence, in Rifreddo, a fairly diversified small vertebrate assemblage has been recovered. The occurrence of Mimomys savini allows to the fauna to be considered as Biharian. The presence of some faunal elements such as Microtus ( Terricola) arvalidens, Microtus ( Iberomys) ex gr . huescarensis-brecciensis, and Macroneomys cf. brachygnathus restricts the age of the Rifreddo assemblage to the latest part of this Mammal Age. In several European localities, sediments containing such late Biharian faunas are correlated with the lower part of Brunhes magnetochrone (e.g. the normally magnetised sections at West Runton in the United Kingdom, Voigtstedt in Germany and Přezletice in the Czech Republic) or just below this boundary (e.g. the negatively magnetised part of the Atapuerca section —levels TD4-6 in Spain). Taking into account the faunal composition and the positive magnetisation of the sediments outcropping at the Rifreddo locality, the chronological referral of the mammal assemblage can be restricted to the early Brunhes and therefore to the early middle part of Middle Pleistocene.

Benthic foraminiferal proxy evidence for the Neogene palaeoceanographic history of the Southwest Pacific, east of New Zealand

Canonical correspondence analysis indicates that the distribution of Neogene benthic foraminiferal faunas (>63 μm) in seven DSDP and ODP sites (500–4500 m water depth) east of New Zealand (38–51°S, 170°E–170°W) is most strongly influenced by depth (water mass stratification), and secondly by age (palaeoceanographic changes influencing faunal composition and biotic evolution). Stratigraphic faunal changes are interpretted in terms of the pulsed sequential development of southern, and later northern, polar glaciation and consequent cooling of bottom waters, increased vertical and lateral stratification of ocean water masses, and increased overall and seasonal surface water productivity. Oligocene initiation of the Antarctic Circumpolar Current and Deep Western Boundary Current (DWBC), flowing northwards past New Zealand, resulted in extensive hiatuses throughout the Southwest Pacific, some extending through into the Miocene. Planktic foraminiferal fragmentation index values indicate that carbonate dissolution was significant at abyssal depths throughout most of the Neogene, peaking at upper abyssal depths in the late Miocene (11–7 Ma), with the lysocline progressively deepened thereafter. Miocene abyssal faunas are dominated by Globocassidulina subglobosa and Oridorsalis umbonatus, with increasing Epistominella exigua after 16 Ma at upper abyssal depths. Peak abundances of Epistominella umbonifera indicate increased input of cold Southern Component Water to the DWBC at 7–6 Ma. Faunal association changes imply establishment of the modern Oxygen Minimum Zone (upper Circumpolar Deep Water) in the latest Miocene. Significant latitudinal differences between the benthic foraminiferal faunas at lower bathyal depths indicate the existence of an oceanic front along the Chatham Rise (location of present Subtropical Front), since the early late Miocene at least, with more pulsed productivity (higher E. exigua) along the south side. Modern Antarctic Intermediate Water faunal associations were established north of the Chatham Rise at 10–9 Ma, and south of it at 3–1.5 Ma. Middle–upper bathyal faunas on the Campbell Plateau are dominated by reticulate bolivinids during the early and middle Miocene, indicative of sustained productivity above relatively sluggish, suboxic bottom waters. Faunal changes and hiatuses indicate increased current vigour over the Campbell Plateau from the latest Miocene on. Surface water productivity (food supply) appears to have increased in three steps (at times of enhanced global cooling) marked by substantially increased relative abundance of: (1) Abditodentrix pseudothalmanni, Alabaminella weddellensis, Cassidulina norvangi (16–15 Ma, increased pulsed productivity); (2) Bulimina marginata f. aculeata, Nonionella auris, Trifarina angulosa, Uvigerina peregrina (3–1.5 Ma, increased overall productivity); and (3) Cassidulina carinata (1–0.5 Ma, increased overall productivity). Three intervals of deep-sea benthic foraminiferal taxonomic turnover are recognised (16–15, 11.5–10, 2–0.5 Ma) corresponding to intervals of enhanced global cooling and possible productivity changes. The late Pliocene–middle Pleistocene extinction, associated with increasing Northern Hemisphere glaciation, culminating in the middle Pleistocene climatic transition, was more significant in the study area than the earlier Neogene turnovers.

LATE PLIOCENE TO MIDDLE PLEISTOCENE EXTINCTIONS OF DEEP-SEA BENTHIC FORAMINIFERA ("STILOSTOMELLA EXTINCTION") IN THE SOUTHWEST PACIFIC

The last major turnover in deep-sea benthic foraminifera (the Stilostomella extinction) is documented in detail in six DSDP and ODP sites around New Zealand, South-west Pacific. This was the final phase in the progressive decline of elongate, cylindrical taxa (mostly stilostomellids, pleurostomellids and uniserial nodosariids), which reached their greatest relative abundance in the late Eocene, and exhibited major declines during periods of global cooling around the Eocene-Oligocene boundary, in late middle Miocene, and through the late Pliocene to middle Pleistocene. The Stilostomella extinction includes the extinction of all elongate species with cribrate ( Chrysalogonium, Cribronodosaria ), slit lunate, hooded with two teeth (Pleurostomellidae), or secondarily toothed, necked (Stilostomellidae) apertures. Elongate and uniserial benthic foraminifera are separated into: an Extinction Group (53 taxa, including several elongate agglutinated and uvigerine forms, that became extinct in the South-west Pacific during the late Pliocene-middle Pleistocene); a Die-back Group (8 species that dramatically declined in abundance but survived to the Recent); and a Survivor Group (88 mostly rare species of uniserial nodosariids with little recognised decline). In the South-west Pacific, the absolute abundance of the Extinction and Die-back groups began to decline in the late Pliocene. The decline became more dramatic during the late early and middle Pleistocene (1.2–0.7 Ma). The rate of decline was pulsed, with major declines usually associated with the onset of cold intervals, and partial recoveries in intervening warm intervals. The pulses varied in timing between sites. The highest occurrences (HOs or local disappearances) of individual Extinction Group species are variable and mostly diachronous between sites. There was a progressively increasing overall rate of local disappearances per time through the late Pliocene (onset of northern hemisphere glaciation) to the middle Pleistocene climatic revolution, with the peak period of local disappearances (mostly 0.9–0.7 Ma) up to 0.5 Ma earlier at deeper and cooler water locations. The youngest occurrence of any member of the Extinction Group ( Stilostomella extinction datum) is remarkably consistent in all sites (0.65–0.57 Ma). The timing of these abundance declines, highest occurrences (or withdrawals) and extinctions was essentially the same as in the Atlantic Ocean. The precise mechanistic cause of the Stilostomella extinction (cooling, increased oxygenation of bottom waters, food supply changes) is yet to be resolved. This study reveals a much larger extinction of taxa than previously recorded (middle Pleistocene extinction rate of 23% of the bathyal-upper abyssal fauna/myr). Becoming extinct, or virtually so, during this period were at least two families (Stilostomellidae, Pleurostomellidae), one subfamily (Plectofrondiculariinae), at least 17 genera ( Awhea, Chrysalogonium, Cribronodosaria, Ellipsoglandulina, Ellipsopleurostomella, Ellipsopolymorphina, Haeuslerella, Mucronina, Myllostomella, Nodosarella, Orthomorphina, Parafrondicularia, Pleurostomella, ? Rectuvigerina, Siphonodosaria, Stilostomella, Strictocostella ) and 53 species. Their taxonomy is reviewed, revealing many synonymies, often going back to Schwager’s (1866) pioneering study of Pliocene deep-sea foraminifera of Car Nicobar, Indian Ocean. A revised generic subdivision of the Stilostomellidae is proposed based primarily on apertural features, and Myllostomella n.gen. described.

Filling and cannibalization of a foredeep: the Bradanic Trough, Southern Italy

Abstract The Bradanic Trough (southern Italy) is the Pliocene-present-day south Apennines foredeep. It is a foreland basin as subsidence due to westward subduction of the Adria Plate involves the continental crust of the Apulian domain. The infill succession of the Bradanic Trough is characterised by the presence of a long thrust sheet system (the so called ‘allochthon’) that occupied part of the accommodation space created on the foreland by subduction. The upper part of the infilling succession crops out along numerous sections. About 600 m of the 3–4 km basin-fill succession is exposed as the Bradanic Trough has experienced uplift during Quaternary times. Outcropping successions are mainly characterized by shallow-marine deposits comprising carbonates of the Calcarenite di Gravina Formation, silty clay hemipelagites of the Argille subappennine Formation and coarse-grained bodies of the ‘Regressive coastal deposits’. The Calcarenite di Gravina Formation (Middle-Late Pliocene-Early Pleistocene in age) crops out in a backstepping configuration onto the flanks of the Apulian Foreland highs. It displays evidence of strong transgression onto a karstic region previously dissected in a complex horst and graben system. The Argille subappennine Formation (Late Pliocene-Middle Pleistocene in age) succeeds the carbonate sedimentation on the foreland side of the basin and represents the shallowing of the basin in the other sectors of the Bradanic Trough. Toward the Apennines chain, in the wedge-top area of the foredeep, the Argille subappennine Formation covers the allochthon, while in the depocentre (in the foredeep sensu stricto ) the same formation overlays turbidite deposits. The latter characterize the deeper part of the successions, and are mainly buried below the allochthon. The Regressive coastal deposits (Early-Late Pleistocene in age) represent the upper part of the succession. They consist of coarse-grained wedges that lie on the hemipelagites of the Argille subappennine Formation in, alternatively, conformable or erosional contact. The wedges of the Regressive coastal deposits stack in a downward-shifting configuration, which indicates deposition during uplift. The Quaternary development of the Bradanic Trough differs from that of the central and northern Appennines foredeep. The latter is characterized by aggradation of shallow-marine and alluvial sediments in a subsiding remnant basin, whose filling records a basin-scale depositional regression. In contrast, the Bradanic Trough is characterized by a basin-scale erosional regression and the last evolutive phase of this sector of the Apennines foredeep is best defined as a cannibalization phase rather than a filling or overfilling phase.

Superimposed brittle structures in the late‐orogenic extension of the Northern Apennine: results from the Carrara area (Alpi Apuane, NW Tuscany)

This paper presents data on the geometric and kinematic features of brittle faults in the Carrara area (Alpi Apuane, NW Tuscany, Italy), providing the first paleostress determination in a key region of the Northern Apennine. Meso‐and microfault analyses point out the presence of brittle structures formed during a polyphase deformation and characterized by an older stage (DS1), with an interfering system of strike slip and normal faulting, followed by the DS2 stage developing normal faults locally showing apenninic trend (NW/SE). As a whole, the brittle structures are related to the late Pliocene–middle Pleistocene evolution of the Thyrrenian side of the Northern Apennine.

鈴鹿山脈東麓地域の第四紀における変形速度

A seismic reflection profile implies that foothills and terrace surfaces in the eastern margin of the Suzuka Range are underlain by an east-facing monocline. Based on the stratigraphy of the late Pliocene-middle Pleistocene Tokai Group and a drill core of 500m deep, we correlated distinct seismic reflectors to the boundaries between the Komeno Formation and the Oizumi Formation of the Tokai Group. Analysis of growth strata demonstrates that monoclinal uplift of the Tokai Group and Paleozoic rocks began since the beginning of the deposition of the lowermost part of the Tokai Group (ca. 3.0Ma). Total vertical growth and shortening of the bottom of the Tokai Group during the deposition of the growth strata are estimated to more than 1, 800m and 1, 000m, respectively. Using an age of 2.9±0.2Ma for the Ichinohara volcanic ash, which overlies near the bottom of the Tokai Group, based on fission track method, uplift rate since late Pliocene is >0.58-0.68mm/yr, and horizontal shortening rate is >0.30-0.37mm/yr. The resulting long-term structural growth rates are comparable to those of the Fumotomura fault during late Quaternary based on previous geomorphic studies, which suggests that the Fumotomura fault is responsible for the growth of the monocline. If so, the fact that terraces are deformed more narrowly than the Tokai Group implies that the monocline and the warping of terrace surfaces is fault-propagation fold.