Chronology of late Pleistocene Pampa loess from the Córdoba area in Argentina

In Argentina, loess/palaeosol sequences were studied from the two sections at Monte Ralo and Corralito, located near to the city of Córdoba in the east of the Pampean ranges. Infrared optically stimulated luminescence (IRSL) and thermoluminescence (TL) dating techniques were applied to set up a more reliable chronological framework for the Upper Pleistocene loess record. IRSL ages increase with depth and are stratigraphically consistent. The oldest loess exposed correlates at least to the penultimate glaciation. The luminescence dating study gives evidence for humid climate conditions with soil formation during the last interglacial period and the middle pleniglacial correlating to Marine Isotope Stage (MIS) 5 and 3, respectively. Three extended periods of soil formation are recorded in the loess/palaeosol sequences at the Corralito section. These buried soils most likely correlate with the last interglacial and early last glacial period. During the Middle Pleniglacial, two palaeosols are intercalated in the loess successions. In the Córdoba area, the periods of increased loess accumulation and deposition of loessic sediments correlate with more arid and glacial periods during the Early Pleniglacial, the Middle Pleniglacial and the Late Glacial. Copyright © 2009 John Wiley & Sons, Ltd.     

The late pleistocene paleoenvironment and paleoclimate of the madaras section (South Hungary), based on preliminary records from mollusks

24 species and 110 506 specimens of mollusks were collected and identified from 250 samples of the loess profile at Madaras, South Hungary. According to changes in the mollusk fauna, six malacological-paleoecological zones can be identified in this profile. The Quaternary malacological data from the Madaras loess section suggest that the Middle and Late Pleniglacial development of the mollusk fauna, and local climatic and environmental conditions in this area differed from other loess regions in Europe.     

The loess sequence of Dolní Věstonice,Czech Republic: A new OSL‐based chronology of the Last Climatic Cycle

The Dolní Věstonice loess section in the Czech Republic is well known for its high‐resolution loess–palaeosol sequence of the last interglacial–glacial climatic cycle (Upper Pleistocene). The loess section is situated in a climatic transition zone between oceanic and continental climates and is therefore of great value in reconstructing past regional climate conditions and their interaction with climate systems, in particular that of the North Atlantic. Based on a combination of optically stimulated luminescence (OSL) ages, stratigraphic field observations and magnetic susceptibility measurements, a chrono‐climatic interpretation of the Dolní Věstonice loess section is presented. To establish a reliable Upper Pleistocene chronology, a quartz OSL approach was applied for equivalent dose (D_e) determination. Monomineralic quartz extracts of three distinct grain sizes, fine (4–11 μm), middle (38–63 μm) and coarse (90–200 μm), were used and compared. Within error limits, the calculated OSL ages are the same for the different grain sizes, and the OSL ages are in stratigraphic order. The established OSL chronology is in agreement with a Weichselian litho‐ and pedostratigraphy. The Dolní Věstonice loess section is characterized by four pedosedimentary subsequences. At the base of the profile, subsequence I is characterized by a distinct Early Glacial soil complex, OSL‐dated to c. 110 to 70 ka, representing one of the most complete records of environmental change in the European loess belt. Subsequence II is allocated to the Lower Pleniglacial and is characterized by laminated sandy loess. Middle Pleniglacial subsequence III is represented by a brown soil complex, and is followed by the uppermost subsequence IV, characterized by a thick body of laminated sandy loess, indicating strong wind activity and a high sedimentation rate of more than ～1 mm a^?1 during the Upper Pleniglacial. According to the OSL chronology, as well as to the sedimentological and palaeopedological investigations, it is likely that the sequence at Dolní Věstonice has recorded most of the climatic events expressed in the NGRIP δ¹⁸O reference record between 110 and 70 ka.     

The impact of Dansgaard–Oeschger cycles on the loessic environment and malacofauna of Nussloch (Germany) during the Upper Weichselian

A loess sequence has been sampled continuously at high resolution in Nussloch (Rhine Valley, Germany) for malacological and grain-size analyses between ca. 34 and 20 ka. Molluscan abundance and richness, percentage in hygrophilous species and grain-size index show cyclical variations related to the lithological loess–gley alternation. Major molluscan abundance maxima were triggered by temperature increases through an enhancement of the reproduction cycle, whereas cyclical richness fluctuations and percentage in hygrophilous species reflect variations in local humidity and changes in the environmental mosaic. Malacological parameters allow the distinction of four environmental phases organised in cyclical successions correlated with most of the loess–gley doublets. The correlation of the grain-size index of the Nussloch loess sequence with the dust content of the GRIP ice core demonstrates the synchronicity of major molluscan abundance maxima and δ¹⁸O increases characterising temperature increases during Dansgaard–Oeschger interstades. A schematic model is proposed to link the North Atlantic Dansgaard–Oeschger climatic oscillations with local environmental changes indicated by both malacofauna and pedostratigraphy. This malacological study of the Nussloch loess sequence thus provides new information about the response of terrestrial loessic palaeoenvironments to millennial-timescale climatic fluctuations during the Upper Weichselian ( marine isotope stage 2 (MIS 2) and end of MIS 3).     

The last 750 ka in loess–palaeosol sequences from northern France: environmental background and dating of the western European Palaeolithic

This study presents an overview of Middle Pleistocene loess–palaeosol sequences (LPS) in northern France and discusses the palaeoclimatic significance of the pedosedimentary record in the context of western European LPS and of global climatic cycles for the last 750 ka. In this area, the oldest loess deposits (early Middle Pleistocene) are preserved in sedimentary traps (leeward scarps of fluvial terraces and dissolution sinkholes). They result from local deflation processes reworking Pleistocene sandy fluvial deposits or relicts of Tertiary sands. A large extension of typical calcareous loess over the landscape, the Loess Revolution, is then observed during MIS 6, with heavy mineral assemblages testifying to long-distance transport from the polar desert area of the dried eastern Channel. A correlation scheme is proposed between the global records of northern France in continental environments and both global palaeoclimatic records and other main western European LPS. After 30 years of research, northern France LPS stand as a fundamental archive of the impact of interglacial–glacial climatic cycles as well as millennial events. Finally, these works provide a robust chronoclimatic framework for the study of the western European Late Acheulean and Middle Palaeolithic and for the relative dating of the various fluvial terraces that they fossilise.     

Chronology of the Last Climatic Cycle (Upper Pleistocene) of the Surduk loess sequence, Vojvodina, Serbia

The Surduk loess section in Serbia provides a 20 m thick pedosedimentary record of the last interglacial–glacial climatic cycle (Upper Pleistocene). Based on optical dating, a chronostratigraphy could be established for the last climatic cycle, yielding the first numerical ages of a loess record from the middle Danube basin. Infrared-stimulated luminescence (IR-OSL) dating has been applied to the polymineral silt fraction using a multiple aliquot additive-dose protocol to determine the equivalent dose ( D _E ). Within error limits, all age estimates are in stratigraphic order. Owing to the application of shine-plateau tests, the samples showed no evidence of insufficient bleaching. The Surduk loess section comprises three major periods of soil formation. Based on the IR-OSL chronostratigraphy, the lowermost pedocomplex is attributed to the Last Interglacial and to the Early Glacial (Marine Isotope Stage – MIS 5e to 5a). The middle part of the section exhibits a succession of weakly developed brown soils and a humic horizon, named 'Surduk soil', formed during MIS 3. On top of the section, recent soil formation is related to the Holocene. Thick loess deposits are preserved between these palaeosols and are attributed to the Lower and Upper Pleniglacials (MIS 4 and 2), respectively. Estimated mean sedimentation rates are 0.1–0.2 mm/yr for the last glacial cycle, with a strong increase to 0.6 mm/yr with onset of the Pleniglacial.     

Terrestrial molluscs as indicators of global aeolian dust fluxes during glacial stages

This paper represents an approach to discerning the kind of climatic signal that land snails might record. The study uses previous analyses of the Achenheim molluscs, whose time series can be compared with ice-core records or marine records. Terrestrial molluscs are characteristic of the environment in which they live, mainly mirroring prevailing climate and vegetation. As a result of this relatively close connection between biotope and mollusc assemblages, reconstructions of past environments can be made that agree generally with results from pollen analyses. In this way, malacofaunas in loess sections permit determination of environmental variability and climatic change. Loess deposits, however, correspond to a particular environment. Decreasing or increasing dust deposition affects the molluscan assemblages by altering the environmental conditions for better or for worse. The variation in the mollusc diversity index in Achenheim shows a striking correspondence with dust-flux variation. There is only a low correlation between diversity index and temperature, precipitation or moisture estimates.     

Last interglacial-glacial climatic cycle in loess-palaeosol successions of north-western France

The loess series at St. Pierre-les-Elbeuf and St. Sauflieu are key successions for the western European Quaternary stratigraphy. The present study proposes a detailed record of the last interglacial-glacial climatic cycle at St. Pierre and its integration into the synthetic pedosedimentary record of north-western France using detailed correlations with the type sections of St. Sauflieu and Achenheim. Finally, comparisons with the marine isotope, Greenland GRIP chronologies and dust records are proposed. At St. Pierre, the pedostratigraphic and sedimentological analyses (total iron, organic matter, carbonate, grain size), in association with low field magnetic susceptibility measurements, demonstrate that this loess succession records the major climatic events of the Upper Pleistocene. The basal soil complex at St. Pierre is similar to those from the main successions of North (St. Sauflieu) or Northeast France (Achenheim). It shows a Bt horizon of brown leached soil, a deeply reworked grey forest soil and two isohumic steppe soils separated by a non-calcareous loess layer. This loess level corresponds to the first aeolian event clearly observed in the succession and can be correlated with Marker II of the Central European stratigraphy located around the marine isotope stage (MIS) 5/4 boundary. The main aeolian sedimentation starts after the soil complex and ends with the top soil (brown leached soil). Finally, a good parallel is observed between the strongest peaks of the dust records of the ice cores and the main period of loess deposition in St Pierre-lès-Elbeuf occurring during MIS 2.     

中国黄土研究新进展(一)黄土地层

本文扼要介绍最近几年中国黄土研究中的土壤地层学、磁性地层学、气候地层学、第四纪下界及海陆古气候对比等方面的新进展。根据新发现的黄土剖面,中国黄土中共可区分出37个土壤地层单位。中国黄土底界的古地磁年龄为2.5MaB.P.。2.5Ma以来,中国北方共经历了37次大的冷暖交替。2.5MaB.P.前后,全球气候出现了一次大的转型事件,它可作为第四纪的开始。中国黄土-古土壤系列同深海氧同位素记录在1.7Ma至今的时段上可以很好的对比;2.5Ma至1.7MaB.P.的气候变化,以黄土记录较为明确。     

Fluvial response to Weichselian climate changes in the Niederlausitz (Germany)

The last glacial shows large variations in climate, which are reflected in the fluvial record in the Niederlausitz, eastern Germany. The entire sequence resembles the fluvial development in other river basins in northwestern Europe, which show contemporaneous changes in depositional style at the onset of a climatic change. During the Middle and the Late Pleniglacial, permafrost conditions resulted in an episodic river discharge. The presence or absence of vegetation, in combination with such ephemeral stream conditions, determined the type of river during each period. A relatively well-developed vegetation cover on the flood plains during the Middle Pleniglacial resulted in a low sediment yield. In combination with the intermittent discharge, this caused the development of an ephemeral anastomosing river system, a river with stable channels and extensive sandy overbank areas. The decline in vegetation cover at ca. 28 ka BP caused an increase in sediment yield and peak discharges, which resulted in the development of a sandy braided river in adjustment to these new conditions. Following the coldest period at around 20 ka, precipitation was so low that fluvial activity was limited and aeolian deposition took place in the valley. © 1997 by John Wiley & Sons, Ltd.     

Mollusc-based paleoecological investigations of the Late Copper — Early Bronze Age earth mounds (kurgans) on the Great Hungarian Plain

The malacological material of the mound bodies (kurgans) of the Great Hungarian Plain indicates a mixed vegetation of dry and humid environments, developed on a mosaic of alkaline and chernozem soils in the period of the construction of the kurgan. The malacofauna that evolved in the upper soil horizon of the mound indicates the extremely dry environmental conditions of steppes, charaterized by the dominance of thermoxerophilous species. Dominant species of this kurgan are Chondrula tridens, Helicopsis striata, Granaria frumentum and Cepaea vindobonensis. The species composition shows that there are differences in the malacofauna of the Danube-Tisa Interfluves region compared to that of the lowlands east of River Tisza, indicated by the higher dominance of Granaria frumentum and Helicopsis striata in the former region. Following the construction of the kurgans an island-like, dry habitat developed on their surface, covered by black soil and populated by a steppe fauna, the composition of which is comparable mostly with the mollusc fauna of loess steppes and forest steppe, irrespectively of the floodplain or wind-blown sand character of the original surface.     

Geochronology of Middle and Upper Pleistocene Loess Sections in Hungary

The application of both thermoluminescence and infrared stimulated luminescence dating to the extensively studied “classical” Hungarian loess/paleosol sequences from Basaharc, Mende, and Paks provides a reliable chronological framework and climatostratigraphic reconstruction for the last interglacial/glacial cycle. Based on this combined luminescence dating study a new chronology is proposed for the “Young Loess” in Hungary. Luminescence dating suggests that the loess below the MF2 horizon formed during the penultimate glaciation. The MF1 horizon probably formed during an interstade within oxygen isotope stage 3. For the youngest loess, overlying MF1, a very high accumulation rate was determined. Large time gaps occur above MF2 and MF1, indicating that most of the record of the last glaciation is missing in the standard sections at Basaharc, Mende, and Paks. Either large discontinuities or a very low accumulation rate occurred in all three type sections during the soil-forming periods. High-resolution studies of climatic proxies using this combined luminescence dating approach provide a reliable chronological framework for loess and loess derivatives of the last glacial cycle in Hungary, although a precise and complete chronostratigraphic reconstruction cannot be achieved from the incomplete records found at these sites.     

Late Quaternary palaeoenvironment and palaeoclimate of the Lake Fehér (Fehér-tó) sequence at Kardoskút (South Hungary), based on preliminary mollusc records

Forty (22 freshwater gastropod, 14 gastropod, 4 bivalves) species and 3428 specimens of molluscs were collected and identified from a 6.3 m sequence, obtained from a core profile, of lake and fluvial sediments at Kardoskút, South Hungary. According to changes in the molluscan fauna, six malacological-palaeoecological zones can be identified in this profile. The Quaternary malacological data from the Lake Fehér core profile suggests that the Late Pleniglacial and Early Holocene development of the molluscan fauna, and local palaeoclimatic and palaeoenvironmental conditions in this area, differed from other regions in Europe.     

Late Quaternary vegetational and climatic change in the Popayán region,southern Colombian Andes

Late Pleistocene and Holocene vegetational and climatic change have been studied palynologically at a site at 1750 m elevation in the subandean vegetation belt near Popayán, in the southern Colombian Andes. Time control on the pollen record is based on six AMS ¹⁴C ages, ranging from possibly Middle Pleniglacial time (around 50000 yr BP) to 1092 ± 44 yr BP. Because of the presence of two hiatuses only the Middle Pleniglacial and Late Holocene periods (the last 2300 yr BP) are represented. Pollen data indicate the presence of closed subandean forest during glacial time. Changes in the contribution of pollen originating from the uppermost and lowermost subandean forest belts, changes in the contribution of a number of other subandean forest taxa, and changes in species composition between the three pollen zones, suggest that the climate during the Middle Pleniglacial was markedly colder, and perhaps also wetter, than during the Late Holocene. Pollen assemblages from the Late Holocene indicate that the landscape has been affected by deforestation and agriculture since at least 2300 yr BP, but that human impact decreased in the last 780 yr BP. © 1998 John Wiley & Sons, Ltd.     

Rapid and cyclic aeolian deposition during the Last Glacial in European loess: a high-resolution record from Nussloch, Germany

This paper reports the results of an investigation of the Weichselian Upper Pleniglacial loess sequences of Nussloch (Rhine Valley, Germany) based on stratigraphy, palaeopedology, sedimentology, palynology, malacology and geochemistry (δ¹³C), supported by radiocarbon, TL and OSL dating. Grain-size and magnetic susceptibility records are taken at 5 cm intervals from the Upper Pleniglacial (UPG) loess. The data indicate cyclic variations in loess deposition between ca 34 and 17 ka, when the sedimentation rate is especially high (1.0–1.2 m per ka for more than 10 m). The grain-size index (GSI: ratio of coarse silt versus fine silt and clay) shows variations, which are assumed to be an indirect measurement of wind intensity. The sedimentation rate, interpreted from the profiles, indicates high values in loess (Loess events LE-1 to LE-7) and low or negligible values in tundra gley horizons G1 to G8. OSL ages from the loess and ¹⁴C dates from organic matter in the loess show that loess deposition was rapid but was interrupted by shorter periods of reduced aeolian sedimentation. Comparison between the data from Nussloch and other European sequences demonstrates a progressive coarsening of the loess deposits between ca 30 and 22 ka. This coarsening trend ends with a short but major grain-size decrease and is followed by an increase to a new maximum at 20 ± 2 ka (“W” shape). Correlation between the loess GSI and the Greenland ice-core dust records, suggests a global connection between North Atlantic and Western European global atmospheric circulation and wind regimes. In addition, the typical Upper Pleniglacial loess deposition begins at ca 30–31 ka, close to Heinrich event (HE) 3, and the main period of loess sedimentation at about 25 ± 2 ka is coeval to HE 2. Correlation of magnetic susceptibility and grain-size records shows that the periods, characterised by high GSI, coincide with an increase in the amount of ferromagnetic minerals reworked from the Rhine alluvial plain. They suggest enhancement in the frequency of the storms from N–NW. These results are integrated within a palaeogeographical model of dust transport and deposition in Western Europe for the Weichselian Upper Pleniglacial (or Late Pleniglacial).     

The Buzzard''s Roost and Eustis mollusc sequences: comparison between the paleoenvironments of two sites in the Wisconsinan loess of Nebraska, USA

We investigated the Upper Pleistocene mollusc sequence in the loess deposit of Buzzard's Roost, Nebraska, and compared the results with those obtained for Eustis, 50 km to the west. Both sequences show similarities in: (i) stratigraphy and magnetic susceptibility implying identical fluctuations in loess deposition, (ii) biostratigraphy which indicates a succession of cold-and-moist to cold-and-dry conditions, and (iii) an increasing trend in mollusc abundance and diversity of species characterizing a climatic and/or environmental improvement. We interpret the variations in both sequences as related to the advance of the James and Des Moines ice lobes towards both sites, which was synchronous with the retreat of the Laurentide Ice Sheet. The occurrence of hygrophilous species in the mollusc record, from the upper sequences of Buzzard's Roost, suggests a moister environment than in Eustis. Our preliminary comparison of both malacological sequences suggests that regional or local, rather than global, influence prevailed over the Great Plains between 20 and 12 kyr BP.     

Late Pleistocene loess‐palaeosol sequences in the Vojvodina region,north Serbia

Late Pleistocene loess‐palaeosol sequences are widespread in the Vojvodina region, with thicknesses reaching a maximum of about 20 m. Our investigations include more than 40 of these loess sections. Geochronology of the last glacial loess‐palaeosol sequences, based on luminescence dating and amino acid racemisation, provides correlations between Upper Pleistocene loess‐palaeosol sediments in Vojvodina and comparable deposits at other European localities. Sedimentary logs of magnetic susceptibility, grain‐size measurements and carbonate content, combined with malacological evidence, indicate two main relatively cold and arid phases during the last glacial period, related to intensive accumulation of loess units L1L1 and L1L2, as well as many brief episodes of dry and windy climatic conditions, suggesting a possible relationship with cold events recorded in the North Atlantic region. Generally, late Pleistocene climate in the region was dry and relatively warm, compared with glacial period sites in central Europe, and was characterised by sharp differences between glacial and interglacial modes. New data and interpretations presented in this study emphasise the significance of loess‐palaeosol sequences in Vojvodina for the reconstruction of the temporal and spatial evolution of late Pleistocene palaeoclimate in this part of Europe. Copyright © 2007 John Wiley & Sons, Ltd.     

Late quaternary of the middle Caquetá River area (Colombian Amazonia)

The late Quaternary history of the middle Caquetá River area in Colombia, northwestern Amazonia is described, based on observations of river bank sections, radiocarbon dates and palynological analyses of organic layers in floodplain and low terrace sediments of the Caquetá River. It is shown that the Late Pleistocene and Holocene climatic changes that took place in the Andean Cordilleras, were related to the depositional and erosional history of the Caquetá River in the Colombian Amazonian lowlands. The low terrace sediments consist of sandy and gravelly deposits covered by clays that sometimes contain lenses of peaty material. From these organic low terrace sediments, seven finite radiocarbon dates were obtained of Middle Pleniglacial age, between 56 000 and 30 000 yr BP. The coarse textured basal deposits of the low terrace apparently stem from the early part of the Middle Pleniglaciai period, during which the effective rainfall in the Andes was relatively high and the Andean glaciers had a considerable extension. Palynological data from silty sediments with organic remains at one site, show an interval when drier and more open types of vegetation on poor soils must have covered a larger area than today, but Amazonian forest was still the dominating type of vegetation. This interval might correspond to one of the Middle Pleniglacial savanna intervals from eastern Amazonia (Carajas). No organic sediments from the Upper Pleniglacial period were found and hence radiocarbon dates were not obtained. In the Andes this period had a very cold climate with low effective rainfall and in the east Amazonian Carajas area it is characterised by the relative extension of open savanna vegetation. The river run-off and sediment transport must have been much lower than in the Middle Pleniglacial and the Caquetá River cut itself down in its own sediments. Two Late-glacial radiocarbon datings obtained at one site (ca. 12 500 yr BP) indicate the existence of a Late-glacial sedimentation phase, separated from the Holocene sequence by a minor erosional phase. Organic layers in the Holocene floodplain sediments yielded 28 radiocarbon dates between 10 000 and 355 yr BP. Holocene sedimentation started with the rapid deposition of (sandy) clay possibly in a partly permanently inundated Caquetá valley. During the major part of the Holocene (silty) clays were deposited, with a dominant seasonal inundation cycle.     

A 350,000-year climatic record from the loess sequence of Achenheim, Alsace, France

Up to now the best Quaternary climatic sequences come from oceanic isotope studies, but terrestrial sequences are also well known, usually for pollen or ice core data. A new sequence providing climatic information for the last 500,000 years has been studied in the loess series of Achenheim (Alsace), using the mollusc record in relation to other stratigraphical data. Mollusc assemblages are analysed using a multivariate method. The correspondence analysis used here allows us to explain, in ecological terms, the general variability of the Achenheim set. Most Pleistocene mollusc species have the advantage that modem individuals live in the same assemhlages. So, the known ecology and distribution of the modern molluscs allow us to conclude that the first two factors explain variations in temperature and moisture. Each loading, on a factor, of each association in its stratigraphical level contributes to characterizing the evolution of each climatic parameter through time. For the last five climatic cycles, these evolutions are expressed as a function of the depth within the series. As they are well preserved, the last three glacial cycles are studied in detail. They correspond to the last 350,000 years, are compared with SPECMAP data and particularly show correlations between continental and marine climatic indicators. The mollusc assemblages of the loess sequence also provide information on temperature and moisture conditions. The evolutions of each parameter are not identical during the last three cycles, indicating that the climatic history of one cycle cannot be transferred to the others. The mollusc assemblages also record the occurrence of an oscillatory system, especially during the Weichselian Upper Pleniglacial (isotopic stage 2) when it announces the Late Glacial variations. Similar oscillating excursions seem to have occurred during the older glacial stages.     

A global perspective of the European chronostratigraphy for the past 650 ka

Characteristic global climatic events are employed to interpret the regional, land-based European stratigraphy. The Chinese loess record shows well expressed, continuous and reliably dated climatic signals of worldwide significance, which are well correlated with the marine oxygen isotope stratigraphy. The sequence in the surroundings of Ferdinandow in Poland plays a key role in the correlation of the European stratigraphy with the loess record and the oxygen isotope record. In particular, the complex but well-expressed Ferdinandowian Interglacial is a key marker because it shows striking similarities with the most pronounced soil complex of the last 700 ka years of the Chinese loess sequence (S5) and, by correlation, Oxygen isotope stages (OIS) 13–15. It follows that the Holsteinian Interglacial corresponds with the S4-soil and OIS 11. This appears to be confirmed by sequences deposited in the craters of the Central Massif, France. Problems of regional stratigraphical correlation in Europe persist, but is suggested that a general framework is now established.