Upper Palaeolithic hunter–gatherer societies in the Basque Country (Iberian Peninsula) in the light of palaeoenvironmental dynamics in the last Glacial Period: cultural adaptations and the use of biotic resources

Terrestrial paleoclimatic and paleoenvironmental records on the Indian monsoon are extremely limited, though many investigations have been done on the deep-sea sediments in the Indian Ocean during the last few decades. In order to clarify the terrestrial monsoonal climatic records during the Quaternary, we undertook core-drilling of the basin-fill sediments of the Kathmandu Valley, which is located under Indian monsoon zone. In this paper, we attempt to reconstruct the environmental changes of the Pakeo-Kathmandu Lake, on the basis of studies on the fossil-diatom collected from a 218-m-long core drilled at Rabibhawan, western central part of Kathmandu. Except the uppermost thin cover of fluvial sediments (Patan Formation), the core is continuous and mainly composed of muddy lacustrine sediments (Kalimati Formation) containing abundant fossil-diatoms, which document ecological responses to climatic and environmental changes (Sakai 2001, Hayashi et al. 2002). Mud samples were collected at 50 cm interval from 7 to 45.5 m in depth and at 2 m interval from 47.5 to 218 m in depth. We identified each species and counted the number of valves by means of a scanning electron microscope (JSM-5600) at x5,000 magnification, because dominant species in the RBcore are very small, ranging from 5 to 30 μm. For each sample, at least 300 diatom valves were counted. On the basis of relative abundance and the number of principal diatoms, eight fossil zones and three subzones in zone 2 were defined in the Kalimati Formation (Figure 1). Zone 8 at the basal part is characterized by variety of diatom assemblages and relatively low number of diatom valves, which reflect marsh or very shallow-water environments. Based on water-level indicators (ratio of planktonic diatoms to benthic diatoms and frequency of genus Aulacoseira), the water-level seems to have deepened gradually from zone 8 to zone 7, and retained deep condition from zone 6 to zone 4. Zones 6 to 4 are characterized by monodominance of Cyclotella: Cyclotella sp.1 is a characteristic in zone 5, and Cyclotella sp.2 is in zone 6 and zone 4. Number of their valves is very abundant. On the other hand, in zone 3 and zone 2, there are several dominant species and number of total diatom valves decreases. Furthermore, ratio of planktonic diatoms to benthic diatoms periodically rises and falls, which probably indicates water-level fluctuations. Especially in zone 2A, fluvial and marsh environments were expanded in marginal area of the lake, because relative abundance and number of Staurosira construens and Pseudostaurosira brevistriata, indicative species for marsh environment, become high. In zone 1, ratio of planktonic diatoms increases, which indicates the water-level rose again. But after zone 1, number of total diatom valves drastically reduces. It demonstrates that the lake was drained during a short period at about 12 ka. Comparison of environmental changes of the PaleoKathmandu Lake with δO record from a core MD900963 collected in the Indian Ocean (Bassinot et al. 1994) for the past 630 ka, shows that the water-level of the Paleo-Kathmandu Lake seems to have fallen at glacial age (MIS 14, 10, 8, 6, 2). We recognized following five major events expressed by high ratio of benthic diatoms, which indicate lowering of water-level. According to the time-scale derived from paleomagnetic study and AMS 14C dating of the core, the following stages correspond to marine isotope stages (MIS) from MIS 14 to MIS 2. Zone 5 ~ zone 4 = MIS 14 Early stage of zone 3 = MIS 10 Later stage of zone 3 = MIS 8 Later stage of zone 2C = MIS 6 Later stage of zone 2A = MIS 2 It is likely that these environmental changes of the PaleoKathmandu Lake mainly caused by fluctuations of Indian monsoon related to global climatic changes (glacial-interglacial cycle).

During the early Pleistocene (prior to 1.25 Ma), obliquity dominated the cyclicity of climatic variations, resulting in glacial and interglacial cycles. A significant change occurred between 1.25 Ma and 0.7 Ma, which altered the dominant frequency from 41 kyr to 100 kyr. This transition period is known as the Mid-Pleistocene Transition (MPT). Although several climate models and records have focused on the MPT, our understanding of how climatic variations in the 41 kyr-world affected the planktonic foraminiferal fauna, and their response to the millennial-scale sea surface temperature (SST) oscillations remains limited. Here, we present a sub-millennial scale planktonic foraminiferal assemblage and G. bulloides stable isotope data from southern Iberian margin IODP Site U1387 (36°48.321´N 7°43.1321´W, 559 water depth), influenced by subtropical surface waters from the Azores current. The main goal is to reconstruct temporal trends in SST and to infer ecological changes during the interval from Marine Isotope Stage (MIS) 50 to MIS 40 (1.5-1.28 Ma).Planktonic foraminifera assemblages show a distinct pattern between glacial and interglacial periods, correlating with changes in the mid-latitudinal North Atlantic's surface circulation. Interglacial periods (MIS 49, MIS 47, MIS 43) exhibit a strong influence of warm, oligotrophic waters. The abundances of subtropical species vary between 40% and 65%, whereas tropical species reach up to 10%. The SSTs were around 23.7°C during summer and 18.5°C during winter. In these periods, insolation appears to influence interglacial intensity, peaking at the onset of MIS 47 and MIS 43. In contrast, during cooler MIS 45, the subtropical species only reached values up to 20% and tropical species up to 2%, with temperatures about 21°C in summer and 16°C in winter. The expansion of the subtropical gyre during the interglacials, but also interstadial periods, could have played a significant role in those species’ assemblages and the SST fluctuations.In contrast, during glacial periods (MIS 50, MIS 48, MIS 46, MIS 44), extreme cold events of short duration were documented, with MIS 50 and MIS 48 recording distinct terminal stadial events. Those short-term episodes were marked by abrupt abundance increases of polar species N. pachyderma up to 40% to 65%, respectively, and SSTs dropping down to 8°C in summer and 5°C in winter. The coldest temperatures were documented during the MIS 48 stadial terminal event and is consistent with alkenone-derived SST data, indicating colder deglacial conditions compared to MIS 46 and MIS 40. The SSTs, and the faunal data, including the increase in cold water calcareous nannofossil taxa, are consistent with evidence of the southward displacement of subpolar waters and the contraction of the subtropical gyre. In addition to the faunal data, changes in the G. bulloides δ18O record reveal a gradual increase of values during MIS 48 and abrupt oscillations during MIS 46, MIS 44, MIS 42, and MIS 40. Overall, we confirm the presence of millennial-scale climate variability during the 41 kyr-world with strong impacts on the planktonic foraminifera fauna and implications for the dimension of the subtropical gyre in the North Atlantic.

ABSTRACTThe cave site of Axlor (Biscay, Spain) preserves one of the most informative Middle Palaeolithic (MP) records for the North Atlantic Iberian region, though its age remains poorly known. Here we use single‐grain optically stimulated luminescence (OSL) and single‐grain thermally transferred OSL (TT‐OSL) dating of sediments to improve the age constraint of Axlor's MP succession (levels N–B). Our new ages are consistent with the previously publishedterminus ante quem14C ages for the site (>42.9 cal kabp), and suggest the sequence accumulated during a period of ~50 kyr. Axlor's levels N–F were deposited ~100–80 ka, probably during marine isotope stage (MIS) 5d–a, while levels D and B were deposited ~70 and ~50 ka, respectively, during MIS 4 and mid‐MIS 3. Our results indicate that major faunal and technological turnovers occurred towards the end of MIS 5, potentially coinciding with broader environmental and climatic changes. Axlor's Quina record, dated here to the onset of MIS 4, is one of the oldest in Europe. Comparisons with neighbouring sites point to complex regional chronologies and development for this particular behaviour, though detailed correlations with other MP sequences remain difficult due to their poor chronological attributes. The present study highlights the important role that single‐grain optical dating can play in elucidating the broader evolution of the MP across southwestern Europe.

Lake sediment records offer insights into past climate and environmental changes. There are, however, few continuous lake sediment records from the Southern Hemisphere mid-latitudes that span the last glacial interval (LGI) and have the requisite chronological control and sampling resolution. Orakei maar paleolake in the Auckland Volcanic Field, New Zealand, is an exception, as it contains a high-resolution record of continuous lacustrine sedimentation from its formative phreatomagmatic eruption ~ 130 ka, until post-glacial sea-level rise breached the crater tuff rim and connected the lake to the sea ~ 9 ka. We used micro-XRF core scanning, dry bulk density, loss-on-ignition and visual facies descriptions to investigate the depositional history of Orakei maar lake as a response to regional and global drivers of climate change, and to erosional events in the lake catchment. The climate history of the lake was divided into six depositional phases: (I) Early warming with frequent in-wash events, followed by climate fluctuations coeval with marine isotope stages (MIS) 5e to mid-5c, (II) Warm, quiescent depositional conditions during mid-MIS 5c to 5a, (III) A colder, windier interval during MIS 4, (IV) Warmer conditions with dominantly autochthonous sedimentation during MIS 3, (V) Cold conditions followed by a slow temperature increase and the onset of sea-level rise during late MIS 2, (VI) Warm conditions that culminated in formation of a peat unit at the top of the Orakei lacustrine sediment sequence, which was terminated by an influx of massive marine muds into the basin at 9.75 ka. Comparison of the inferred climate evolution at Orakei with climate inferences from the global marine benthic MIS record during LGI shows general agreement, though inferred climate changes consistently occur earlier at Orakei than in the MIS. There is also general agreement in temperature changes inferred from the Orakei record and from other regional lake sediment records, but more detailed comparison requires additional proxy climate data such as pollen, organic geochemistry and biomarkers, to better understand discrepancies between some records. This study demonstrated the great potential of the Orakei record for paleoclimate inference and the applicability of micro-XRF core scanning data for addressing questions about paleoclimate and paleoenvironment. It also highlighted past intervals that require further study.

Litho-, pedo- and palynological analyses constrained by radiometric dating of two loess–palaeosol sequences, Nahirne and Velyka Andrusivka, exposed in a cliff at the eastern edge of the Dnieper Upland, Ukraine, document regional environmental changes in the western marginal zone of the Dnieper lobe. The postglacial loess sedimentation cycle was initiated during MIS 8, immediately after the ice sheet recession. On the basis of palaeorelief analysis, subsequent morphogenetic stages of the original postglacial relief, associated with the modifying and masking role of the loess, and destructive slope processes were reconstructed. Periglacial steppe with consistently present scattered trees formed the Pleistocene landscape in the Middle Dniester area during the last three glacial periods. In such an environment, the following loess beds, correlated with marine isotope stages (MIS), were deposited: Dnieper ( dn ) – MIS 8, Tyasmyn ( ts ) – MIS 6, Uday ( ud ) – MIS 4 and Bug ( bg ) – MIS 2. During the last two warm periods: Kaydaky ( kd ) – MIS 7 and Pryluky ( pl ) – MIS 5, the landscape was not fully forested. As a result, the individual palynological features of these soils show a diverse character. The TL and OSL dates form a sequence with numerous inversions that are difficult to interpret. Although these data do not significantly influence the interpretation, they show that: 1) there are loesses that undoubtedly formed after the maximum extent of the ice sheet by short-distance transport of dust material from local fresh glacial deposits and the underlying Paleogene rocks; 2) date distortions result from the activities of an exceptionally rich pedofauna that has contaminated the material not only in the soil sections of the profile but also in the adjacent loess. It is possible to delimit a few stages of pedofaunal activity in each of the soil units.

A 450-kyr planktonic foraminiferal assemblage record of IODP site U1352 and its implications for the migration of the subtropical front in the south-west Pacific

Different nature of glacial CaCO3 constituents between MIS 2 and MIS 12 in the East Sea/Japan Sea and its paleoceanographic implication

Glacial-interglacial environmental changes in the Drake Passage over the past 600 kyrs

Marine Isotope Stage 3 (MIS3) was a relatively warm and humid, although variable, time in the last glacial period in the northern hemisphere. This climate phase is well‐recorded in various archives (e.g., ice cores, speleothems, and loess) from many parts of the world, including China, although its expression (e.g., warm–humid vs. cool–dry) differed between the hemispheres. However, despite its location in a critical climatic boundary zone and high sensitivity to climate changes, few studies have investigated the MIS3 climate based on the loess records in the Hanzhong Basin (China). In this study, we performed systematic sampling of a loess−paleosol sediment sequence and performed physicochemical analyses and optically stimulated luminescence dating after detailed field observations and descriptions. The results indicated that the time of formation of the lower part of the Malan loess ( L 1 − 2 ) occurred between 55.0–25.6 ka BP, corresponding to MIS3. The magnetic susceptibility, clay content (<5 μm), a *, a */ b *, and contents of Fe 2 O 3 , Al 2 O 3 , Chemical Index of Alteration, and eluvial coefficient were all significantly higher, while the sand content (>50 μm), L *, ba , a , and the contents of Na 2 O, CaO, and Na/K were lower than those in the loess L 1 − 1 (corresponding to MIS2). These findings indicate that the degree of weathering of the loess in MIS3 was higher than that in MIS2, suggesting that the change to a warm–humid climate during MIS3 is reflected in the sediment of the Hanzhong Basin. However, the climate was not as warm or as humid as that during the mid‐Holocene, as indicated by the weaker degree of weathering of the paleosol S 0 . The climate fluctuated obviously during MIS3, including three warm–humid intervals and three dry–cold intervals. Although the relatively warm–humid and unstable characteristics of the late MIS3 in the Hanzhong Basin are similar to the climate records in other parts of the world, they are considered to be regionally specific responses of the Hanzhong Basin to global climate change.

This study aims to reconstruct the surface water productivity and related monsoonal intensity along the southwestern continental margin of India, over the last 150,000 years by utilizing the temporal variations of δ18O and δ13C isotopes in the planktic foraminifers (Globigerinoides ruber) from a sediment core obtained from the continental slope off Kochi, south-eastern India. The chronostratigraphy of the core is established on the basis of high resolution stable isotope record of planktic foraminifera (Globigerinoides ruber) and a few AMS radiocarbon ages. Down-core records of δ18O and δ13C show millennial scale variations of primary productivity and monsoonal intensity during past 150 kyr. Boundaries of the Marine isotope stages (MISs) were delineated in the core based on the visual comparison of the δ18O with Martinson’s (D. M. Martinson, N.G. Pisias, J.D. Hays, J. Imbrie, T.C. Moor Jr, N.J. Shackleton, Age dating and the orbital theory of the ice ages: development of a high resolution 0 to 300000 year chronostratigraphy, Quaternary Research, 1987 27, p 1-29) and the SPECMAP data. From these studies it is inferred that the bottom of the core is about 150 kyrs, demarcating the paleoclimatic/paleoceanographic information covering MIS 1 to 6. Boundaries among MIS 6 and MIS 5, MIS 5 and MIS 4, MIS 4 and MIS 3, MIS 3 and MIS 2 and MIS 2 to MIS 1 (Holocene) have been demarcated at depths 11.47 m, 4.68 m, 4.03 m, 18 m, and 21 m respectively in the core studied. MIS 5 section is characterized by alternating warm and cold periods as observed in Polar Ice cores. The main findings of this work indicates that the core site has recorded higher productivity with increased fluvial input during the warm, humid interglacial periods and interstadials than the stadials during the glacial period. However, the temporal variability from 150 kyr to 130 kyr has been considered as the glacial period with cold and dry climate that corresponding to the MIS 6, MIS 4 within this an episode of extremely low terrigenous input with heavier δ18O values is noticed from 12.91 to 12.67 m. Similarly, a period of heavy δ18O values, with less surface runoff and with low δ13C values between 4.03 to 4.68 m bsf has been interpreted as MIS 4. Episodic fluctuation in SW monsoon induced productivity during MIS 3 has been observed in present study. The de-glacial event in MIS 2 marked in present core characterized by an abrupt increase in productivity during the mid-MIS 2.

This study aims to reconstruct the surface water productivity and related monsoonal intensity along the southwestern continental margin of India, over the last 150,000 years by utilizing the temporal variations of δ18O and δ13C isotopes in the planktic foraminifers (Globigerinoides ruber) from a sediment core obtained from the continental slope off Kochi, south-eastern India. The chronostratigraphy of the core is established on the basis of high resolution stable isotope record of planktic foraminifera (Globigerinoides ruber) and a few AMS radiocarbon ages. Down-core records of δ18O and δ13C show millennial scale variations of primary productivity and monsoonal intensity during past 150 kyr. Boundaries of the Marine isotope stages (MISs) were delineated in the core based on the visual comparison of the δ18O with Martinson’s (D. M. Martinson, N.G. Pisias, J.D. Hays, J. Imbrie, T.C. Moor Jr, N.J. Shackleton, Age dating and the orbital theory of the ice ages: development of a high resolution 0 to 300000 year chronostratigraphy, Quaternary Research, 1987 27, p 1-29) and the SPECMAP data. From these studies it is inferred that the bottom of the core is about 150 kyrs, demarcating the paleoclimatic/paleoceanographic information covering MIS 1 to 6. Boundaries among MIS 6 and MIS 5, MIS 5 and MIS 4, MIS 4 and MIS 3, MIS 3 and MIS 2 and MIS 2 to MIS 1 (Holocene) have been demarcated at depths 11.47 m, 4.68 m, 4.03 m, 18 m, and 21 m respectively in the core studied. MIS 5 section is characterized by alternating warm and cold periods as observed in Polar Ice cores. The main findings of this work indicates that the core site has recorded higher productivity with increased fluvial input during the warm, humid interglacial periods and interstadials than the stadials during the glacial period. However, the temporal variability from 150 kyr to 130 kyr has been considered as the glacial period with cold and dry climate that corresponding to the MIS 6, MIS 4 within this an episode of extremely low terrigenous input with heavier δ18O values is noticed from 12.91 to 12.67 m. Similarly, a period of heavy δ18O values, with less surface runoff and with low δ13C values between 4.03 to 4.68 m bsf has been interpreted as MIS 4. Episodic fluctuation in SW monsoon induced productivity during MIS 3 has been observed in present study. The de-glacial event in MIS 2 marked in present core characterized by an abrupt increase in productivity during the mid-MIS 2.

We present 23 new thermal ionization mass spectrometric U-Th dates for Victoria Cave, North Yorkshire, UK. Victoria Cave underwent repeated glaciation during the late Pleistocene and contains one of the longest Quaternary cave sequences in Britain. The dates reveal that speleothem formation began beyond the range of the dating technique (before 600 ka). Finite reproducible dates of 490 −9/+10 ka confirm speleothem deposition during marine isotope stage (MIS) 13, the oldest date we know of for this part of Britain. Further speleothem formation was dated to MIS 11, MIS 9, MIS 7, and MIS 5. The results are the basis for a new chronology of Quaternary events for the cave and greatly enhance our understanding of the factors affecting the formation of the sedimentary sequence. Cyclical climatic and environmental change throughout the late Pleistocene triggered cyclical sedimentation events in the cave. All the interglacial periods show calcite deposition but with growth phases postdating the warmest events of MIS 11 and MIS 5e. The position of the cave halfway up the side of a glacial trough resulted in very distinctive sediment during the more extreme glacial maxima: ice-dammed lakes formed inside the cave and deposited varve-like clay rhythmites. The dates inferred for these deposits suggest that this locality underwent significant glaciation during MIS 12, MIS 10, MIS 6, and MIS 2, and that the ice was warm based. The absence of rhythmites during MIS 8 suggests minimal ice cover at that time. This is the most complete record for glacial events in the region; it is the only site where successive glacial maxima can be identified and dated. The record of large faunal remains indicates that the cave was open to the surface, only for relatively short times, during MIS 13, MIS 12, MIS 5e, the Late Glacial Interstadial, and parts of the Holocene. It is inferred that at other times the cave was closed because scree formation blocked the entrance. The record of vertebrate remains is therefore controlled by geomorphological processes. The deteriorating state of this unprotected site remains a cause for concern.

Quaternary ice thinning of David Glacier in the Terra Nova Bay region, Antarctica

Palaeoclimate in the Low Tatras of the Western Carpathians during MIS 11–6: Insights from multiproxy speleothem records

Past climate changes over South Korea during MIS3 and MIS1 and their links to regional and global climate changes