Loess Record Research Articles

The relationship between the loess stratigraphy in the Vojvodina region of northern Serbia and the Saalian and Rissian Stage glaciations – a review

The regional loess stratigraphy in the Vojvodina region, in the southeastern Carpathian Basin, has often been successfully correlated to the global palaeoclimate. This is a quasi‐continuous sedimentary record that provides detailed environmental reconstruction during the last four glacial/interglacial cycles. In this study, we present a standardized loess stratigraphy and illustrate how it correlates with the marine oxygen isotope and Chinese loess stratigraphical records. We argue that the loess stratigraphy in Vojvodina region is an important link in the integration of European terrestrial stratigraphical schemes and the deep‐sea stratigraphical model. We highlight how the loess record can better illustrate terrestrial environmental change through multiple glacial cycles than other records, such as glacial records. The investigated loess record enables direct links to be made between the loess sediments and their glacial sources. This reveals evidence of glaciations during every glacial cycle of the Saalian Stage complex, equivalent to Marine Isotope Stage (MIS) 10, 8 and 6. Therefore, Serbian loess has the potential to provide a direct link between terrestrial glaciations and wider records of global climate change, which is an enigma for many other continental records. These loess records display a strong relationship with the intensity of European glaciations during different glacial cycles. Loess sedimentation rates are highest in the most intensive European glaciation of the Saalian complex (MIS 6) and much lower during the weaker ‘missing’ glaciations equivalent to MIS 8 and 10. A key observation from the Vojvodina loess is the gradual increase in interglacial aridity through the late Middle Pleistocene. The explanation for the progressively increasing aridity in the investigated region at this time is still unclear. However, this trend is consistent with the idea of the Saalian complex as representing a 400 ka mega glacial cycle modulated by shorter classic 100 ka glacial cycles.

Changes of provenance of loess deposits in Nyingchi, southeastern Tibetan Plateau: Implications for paleoclimates since the last glacial

Paleoenvironmental conditions on the southeastern Tibetan Plateau (TP) during the last glacial period are still unclear. Here, we present a loess record (LZP) in the Yarlung Zangbo River (YZR) valley of the southeastern TP, extending over the past 33 ka. Based on grain size, magnetic susceptibility, major and trace elements, sources of loess during different periods were discriminated. Combined with bulk biogeochemical properties (TOC and δ13Corg), as well as comparisons to regional paleoclimate records, the paleoclimate and environmental implications of the LZP loess were further revealed. During 33.4–24.5 ka and 8.4–0.5 ka, loess deposits were mainly derived from nearby river valley while undergoing a relatively strong Indian summer monsoon (ISM). The period of 24.5–15.4 ka witnessed a notable decrease in the contribution of nearby sources and an increase in the contribution of distant materials. The dramatic changes in loess provenance may be due to the development of a paleo-dammed lake in the YZR valley, coupled with the impact of a weak ISM. The sediment contribution of nearby sources increased during 15.4–8.4 ka due to shrinkage or disappearance of the paleo-dammed lake and enhanced ISM. Furthermore, four warmer and wetter events occurred at 31–29 ka, 26.8–25 ka, 22.3–21 ka and 15.5–14 ka were revealed by the LZP record and correspond to enhanced ISM. Our research indicates the complex responses of loess deposits in the southeastern TP to global climate change and local environmental events.

High-resolution luminescence chronology of loess-paleosols reveals East Asian summer monsoon and winter monsoon variation in Hexi Corridor during the past 25 kyr

The variability and interaction of the East Asian summer monsoon (EASM), East Asian winter monsoon (EAWM) and Westerlies dominate mid-latitude Asian hydroclimate and influence over a billion lives in Asia. However, how variation in the EASM, EAWM and Westerlies influences climate change in their transition zones in NW China remain unclear. Specifically, how these atmospheric systems interact during strong-weak phases variation over different timescales is still hotly debated. This study investigates four loess-paleosol sequences in the transition zone between EASM and Westerlies-influenced areas along the central Hexi Corridor of NW China, and presents 63 quartz optically stimulated luminescence (OSL) ages to generate the most detailed chronology for any loess record within the Hexi Corridor. In combination with sedimentology, proxy indexes of magnetic parameters (χlf, χfd, χARM/SIRM) and grain size of these loess-paleosol sequences, and TraCE-21 ka climatic modelling, the loess deposition and climatic changes at central Hexi Corridor regions over the past 25 ka are reconstructed. Our results indicate that: (1) loess deposition initiated by at least 25 ka at Hexi Corridor. Loess depositional rates decrease from late last glacial into the Holocene, with maximum accumulation rates (140–180 g/cm3/ka) occurring during the Last Glacial Maximum. Depositional hiatuses up to 8 ka are recognized in late Quaternary Hexi Corridor loess, which suggests that high-resolution chronologies are necessary for robust paleoclimatic reconstructions from loess records in the region. (2) Over glacial-interglacial cycles, climate in the Hexi Corridor demonstrates a cold-dry glacial and a warm-moist interglacial, consistent with moisture changes observed in the monsoonal Chinese Central Loess Plateau and Westerlies-dominated Central Asia. However, moisture in central Hexi Corridor increased from the early Holocene to mid-Holocene, with a wettest period at 8–7 ka, and followed by a relatively wet late Holocene. These changes are most consistent with the EASM-dominated Chinese Central Loess Plateau and suggests that Westerlies influence in the central Hexi Corridor is minor over at least the past 25 kyr. (3) EAWM intensities demonstrate an anti-phase relationship to EASM intensities over the past 25 kyr in the Hexi Corridor, with decreasing EAWM intensity into the early-mid Holocene and an increase into the late Holocene. (4). EASM precipitation variability in the Hexi Corridor appears to not to be a direct nor singular response to changes in 30°N summer insolation. EASM lags insolation by 3 kyr during the Holocene, supporting the idea that high-latitude forcing through changes in ice volume, greenhouse gases, and/or meltwater input to North Atlantic and Southern oceans can effectively modulate EASM intensity and critically influence Hexi Corridor paleoclimatic conditions.

Climate changes in the Hexi Corridor, western China over the past 13.3 ka

The changing position of the northern boundary of the East Asian summer monsoon (EASM) on different timescales is important for a better understanding of future environmental changes at the edge of this monsoon's influence. Here, we have reconstructed climate changes in the central Hexi Corridor, located at the monsoon-westerlies transition zone of western China, over the past 13.3 ka. Our element data from a loess record suggest a wetting trend through the Holocene, which is different from the climate pattern observed in areas influenced by the monsoon, but consistent with sites influenced by westerlies. Comparisons indicate that the average location of EASM northern boundary in northwestern China during the early to middle Holocene was ∼300 km further northwest than today. Our Zr/Rb and grain size abundance data suggest a significant 500-year periodicity in the intensity of the East Asian Winter Monsoon (EAWM), which most likely originated from AO/NAO changes linked to solar output cycles.

Local Differentiation in the Loess Deposition as a Function of Dust Source: Key Study Novo Orahovo Loess Paleosol Sequence (Vojvodina, Serbia)

Typical patterns of the Late Pleistocene loess–paleosol units are preserved in the Novo Orahovo brickyard, Northern Serbia. Presented preliminary luminescence chronology supports the chronostratigraphic interpretations of global isotopic marine climate reconstructions. Magnetic susceptibility and sedimentological evidence exhibit general similarities with the marine oxygen-isotope stratigraphy. These records provide new insights into the dust accumulation regimes over the eastern side of the Bačka loess plateau and offer new paleoenvironmental information for the region. They represent an important step forward towards the establishment of a catena from the thin loess-like sediments of the Banat foothills in the east towards the thicker and seemingly more complete loess sections of the southeastern and central Carpathian Basin. Grain-size data from the loess record of Nova Orahovo explain the regional differentiation in dust deposition.

Effective Moisture Evolution since the Last Glacial Maximum Revealed by a Loess Record from the Westerlies-Dominated Ili Basin, NW China

Moisture variation is extremely relevant for the stability of ecosystems in Central Asia (CA). Therefore, moisture evolution and its potential driving mechanism over the region are always a hot research topic. Although much effort has been devoted to understanding the processes of moisture evolutions in CA during the Quaternary, particularly the Holocene, the associated underlying mechanisms remain in a state of persistent debate. In this study, the granulometry, clay mineral and chroma properties of a loess section (named ZSP section) in the westerlies-dominated Ili Basin, NW China are investigated. With the accelerator mass spectrometry radiocarbon dating (AMS 14C)-based Bayesian age–depth model, we provide a sensitive record of effective moisture evolution since the last glacial maximum (LGM) in the basin, and the results help enhance understanding of the possible driving mechanisms for westerly climate change. Comparisons of clay mineralogy indices shows that the study area is involved in the Northern Hemisphere dust cycle processes as a dust source, and the content of <2 μm grain size fraction in the ZSP section can thereby be used to reflect the westerlies’ intensity. After deducting the complicated influencing factors for lightness changes throughout the section, the calibrated lightness is adopted to indicate the regional effective moisture. Our findings show that effective moisture is relatively abundant during the LGM and the middle–late Holocene, with dry climate conditions during the last deglaciation and early Holocene. We argue that westerlies’ intensity was the main factor for driving the effective moisture evolution in the Ili Basin since the LGM. Local and source evaporation intensity and effective intra-annual control time of the westerlies over the study area exerted a minor influence on the moisture changes.

Bond events in the Tarim Basin: The loess record

Regional responses to Bond events during the Holocene are important components of paleoclimate and environmental change research. However, there are few records of Bond events during the Holocene in arid central Asia; such events remain poorly understood in this region because of a lack of continuous and high-resolution deposits. Here, new magnetic and grain-size records from a loess sediment sequence located on the southern margin of the Tarim Basin (TB) are provided, which exhibit strengthened dust activity at 9.6–9.4, 8.2–7.8, and 5.5–5.2 ka BP. These periods of strengthened dust activity during the early and middle Holocene in the TB are consistent with Bond events revealed from ice raft detritus in the North Atlantic, and abrupt climate events recorded by loess deposits, lake deposits, and stalagmite oxygen isotopes in arid central Asia and east Asia. We suggest that a delayed seasonal jet transition, resulting from the intensification and southward-shift of the westerly jet during Bond events, plays a key role in creating conditions in the TB that favor strengthened dust activity.

Implications of the loess record for Holocene climate and human settlement in Heye Catchment, Jiuzhaigou, eastern Tibetan Plateau, Sichuan, China

AbstractWe examine the Holocene loess record in the Heye Catchment on the margins of the Tibetan Plateau (TP) and China Loess Plateau (CLP) to determine: the region to which the Heye Catchment climate is more similar; temporal change in wind strength; and modification of the loess record by mass wasting and human activity. Luminescence and radiocarbon dating demonstrate loess deposited in two periods: >11–8.6 ka and <5.1 ka. The 8.6–5.1 ka depositional hiatus, which coincides with the Mid-Holocene Climatic Optimum, is more similar to the loess deposition cessation in the TP than to the loess deposition deceleration in the CLP. Grain-size analysis suggests the Heye loess is a mixture of at least three different grain-size distributions and that it may derive from multiple sources. A greater proportion of coarse sediments in the older loess may indicate stronger winds compared with the more recent depositional period. Gravel incorporated into younger loess most likely comes from bedrock exposed in slump scarps. Human occupation of the catchment, for which the earliest evidence is 3.4 ka, postdates the onset of slumping; thus the slumps may have created a livable environment for humans.

Last glacial loess dynamics in the Southern Caucasus (NE-Armenia) and the phenomenon of missing loess deposition during MIS-2

The Marine Isotope Stage (MIS) 2 is considered the coldest, driest and stormiest period during the last Glacial-Interglacial cycle in large parts of Eurasia. This resulted from strongly decreased northern hemisphere temperature and related maximum extension of northern ice sheets that strongly reinforced large-scale circulation modes such as westerlies and East Asian Winter Monsoon driven by the Siberian High. Normally, this intensified circulation is reflected by maximum loess deposition in numerous loess regions spanning Europe and Asia. However, here we present a new loess record from the Caucasus region in NE-Armenia providing evidence in support of heavily reduced or even lacking loess formation during the MIS-2. Owing to implementations of comprehensible luminescence dating work and a provenance survey using rock magnetic and geochemical data, we are able to define distinct loess formation phases and to retrace sediment transport pathways. By comparing our results to other Eurasian palaeo-records, we unveil general atmospheric circulation modes that are most likely responsible for loess formation in the Southern Caucasus. Moreover, we try to test different scenarios to explain lacking loess formation during MIS-2. In line with other archive information, we suggest that loess formation was hampered by higher regional moisture conditions caused by a southward-shift of westerlies and renewed moisture absorption over the Black Sea. Our results show that modifications of MIS-2 circulation modes induced a very heterogeneous moisture distribution, particularly in the lower mid-latitudes of Eurasia producing a juxtaposition of very dry (morphodynamically active) and moderately dry (morphodynamically stable) areas.

Evaluation of geochemical proxies and radiocarbon data from a loess record of the Upper Palaeolithic site Kammern-Grubgraben, Lower Austria

Abstract. Two loess sections from the Upper Palaeolithic site of Kammern-Grubgraben (Lower Austria) were analysed to test geochemical proxies, as well as radiocarbon data of different components, for their reliability and consistency in an archaeological context. Only a reliable basal age (28.9–27.8 ka cal BP) was obtained from charcoal fragments derived from a tundra gley underlying the archaeological horizons and assigned to Greenland Interstadials 3 or 4. Grain size, organic and inorganic geochemistry, and stable isotopes of the fine organic fraction (δ13Corg) and of rhizoconcretions (δ13C, δ18O) were analysed to provide information on palaeoenvironmental conditions. Low-resolution geochemical and sedimentological analyses document a humidity-related variability, while δ13Corg values indicate predominant C3 vegetation. High-resolution elemental variations derived from X-ray fluorescence scanning exhibit increasing Ca and decreasing Fe and Ti values, indicating drier conditions towards the top. Secondary pedogenic carbonate concretions provide post-sedimentary (Holocene) ages and are not suitable for assessing climate and environmental changes for the Palaeolithic.

Weakened dust activity in southern Central Asia during Heinrich events

Central Asia is one of the dustiest regions of the world, although our understanding of its dust activity over time is limited due to the paucity of continuous, high-resolution, geological records with robust chronologies. In this study, we explore the particle size characteristics of an age-constrained high-resolution last glacial loess record in Tajikistan, southern Central Asia, with a view to reconstructing associated climate dynamics. In contrast to the situation in northern Central Asia and northern China, our results indicate that dust activity declined during Heinrich events and increased during interstadials. It is proposed that dust emission and transportation conditions played an important part in determining regional dust activity and that the role of reactivated paleo-dust has been underestimated. Not only annual humidity but also seasonal humidity should be considered in the paleo-dust activity investigation.

Potential drivers of disparity in early Middle Pleistocene interglacial climate response over Eurasia

Poor understanding of the differential evolution of interglacial climate over various regions in Eurasia greatly limits our ability to predict the specific local impacts of future climate change. Here we demonstrate starkly opposing trends in interglacial intensities in Asia and Europe over the early Middle Pleistocene and Mid-Brunhes Transitions based on the study of various climate proxies in the Paks loess record (Hungary), a key profile in the European Loess Belt. These contrasting climate trends imply major but unexplained differences in the regional response of Quaternary climate to shifts in forcing mechanisms during two major reorganizations of Earth's climate across Eurasia. Using new rock magnetic datasets from the Paks record we suggest that the changing dominance of Mediterranean, Atlantic (Westerlies) and continental air masses under the influence of the quasi permanent high pressure centres over the Fennoscandian ice sheet played a key role in the observed differences in the evolution of early Middle Pleistocene climate. We also propose that the intensification of the early Middle Pleistocene glaciation of Central Asian mountains may have strengthened and shifted the Siberian High westward on multi-millennial/orbital timescales, which in turn forced geographically contrasting expressions of the MIS 19 to 11 interglacials in Eurasia. This is the first coherent explanation for the geographically diverse response of regional climate to the early Middle Pleistocene climate transitions and points to the clear role of global cooling and expanded mid-latitude glaciers in driving these events. • Wind patterns and precipitation are reconstructed from a European key loess sequence. • Disparity in early Middle Pleistocene interglacial climate response over Eurasia is recognized. • Potential drivers of the disparity are proposed, and a conceptual climate model was built.

The close-space luminescence dated loess record from SW Junggar Basin indicates persistent aridity during the last glacial-interglacial cycle in lowlands of Central Asia

Our understanding of how Central Asia evolves in response to climate change remains poorly constrained primarily due to the lack of sufficient paleoclimate records across different altitudinal zones with the adequate resolution for reconstructions. Using a 23.8 m thick loess sequence in the SW Junggar Basin, we establishe a robust chronology over the past ~150 kyr based on K-feldspar pIRIR techniques and Bacon age-depth modelling. To further track the paleoclimatic evolution of this part of Central Asia, this study documents changes in grain size, magnetic susceptibility, CaCO3 content, and sediment color. Together with previously reported loess records from the slopes and intermontane basins of the Tianshan Mountains, altitudinal and spatial variability in moisture changes during the last glacial-interglacial cycle are clarified in Central Asia. Our results indicate that loess in the SW Junggar Basin and northern slopes of Tianshan Mountains was mainly deposited during the Penultimate Glacial and Last Glacial periods. However, the deposition rates were relatively very slow deposition and/or deposited loess records have been entirely eroded possibly due to the deflation in the last interglacial and Holocene. The enhancement of the winter monsoon plays an important role in the rapid deposition of loess in Central Asia during glacial periods. Findings support that the continuous aridity prevailed in the lowlands of the Junggar Basin and the northern slope of Tianshan mountains during the last glacial-interglacial cycle, which is in opposition to the moist interglacial and dry glacial changes recorded in the higher altitude intermontane and mountain areas of the Tianshan Mountains. Limited Westerlies precipitation and high evaporation in lowland areas of Central Asia are responsible for prevailing aridity in these regions during interglacial periods.

Loess-paleosol record of MIS 3 - MIS 2 of north-east Cis-Salair plain, south of West Siberia

We present results for three sections with a representative loess record of the end of the Late Pleistocene from the south-east of Western Siberia. These sections are characterized by different structure and formed in different geomorphological position of Ob Loess Plateau and Cis-Salair plain. The age of deposits within MIS 1 - MIS 3 is determined by radiocarbon and OSL dating. Data on the quartz grain morphology confirmed that aeolian processes were the main factor in the accumulation of studied profiles, the influence of cryogenic weathering was also noted. Evidence of the MIS 2 warmings have been recorded in the northwestern Salair region (Ust’-Chem section), presented by two weakly developed Late Glacial paleosols formed 14.9–12.3 kyr ago. The distribution of magnetic susceptibility and grain size records in the Lozhok and Klyuchi sections reveals a period of relatively long term aridization with an increase in atmosphere dustiness in the lower part of the Eltsovka loess (MIS 2). The trend of increase in humidity with decrease in the atmosphere dynamics is observed during the second part of MIS 2. An event of activation of local aeolian processes with dune formation took place 47 kyr ago (the first half of the Karga interstadial; MIS 3) in the Klyuchi section. It is supposed that the geomorphological situation and the presence of nearby material available for local redeposition was a significant agent in the formation of the lower layer of Klyuchi and Ust-Chem sections. It was formed by combined deposition of silt material from the atmosphere flow and by the local aeolian transportation of sand. Permafrost-solifluction event was established in the northeastern part of the Ob Loess Plateau at about 23 ka.

Les nappes alluviales de la Basse Somme revisitées

The new approach of the fluviatile sequence preserved downstream of Abbeville from Port-le-Grand to Saint-Valery, brings together two sets of complementary data in a same canvas. The first set combines the field records of V. Commont and A. Briquet slightly above the basal cravels. The second set encompasses the data gained for the high and very high terraces mapped in the eighties. They point to a succession of ten main terraces and two second order ones, occurring in continuity with the Abbeville terrace system. The upper terrace being related to Jaramillo, we are dealing with one million year strong regional record with a high-resolution palaeoenvironmental signature fitting in with the ODP 677 marine isotopic record and with the Chinese loess record. In this way, the laminar tool-kit of Croix-l’Abbé could be positioned in the middle part of MIS 8, around 250 ka.

Stepwise coupling between Chinese loess deposition and global temperature since the early Pleistocene tested by a multiple-state model

Chinese loess deposits provide a valuable archive of East Asian monsoon variations and compare well with marine oxygen isotope records. However, post-depositional pedogenesis disturbances during some long and warm interglacials may decrease the time resolution and recording efficiency of loess deposits. In this study, we build a simple multiple-state model that involves deposition and pedogenesis processes to simulate loess-paleosol grain size variations and evaluate the recording efficiency under the impact of pedogenesis disturbance. Meanwhile, the modeling results are compared with the measured grain size time series of Xifeng profile from the center of the Chinese Loess Plateau (CLP). The results show that the recording efficiency of the loess deposits in the central CLP has been stepwise enhanced since the early Pleistocene. High-latitude signals in the Chinese loess record between 2.5 and 1.6 Ma were partly erased by post-depositional pedogenesis and only those from several intense glacial periods remain better preserved. Three finer-grained loess units appear at ~550 ka (marine isotope stage (MIS) 14), ~1045 ka (MIS 30), and ~1500 ka (MIS 52), which were likely caused by low dust accumulation rates, suggesting the moderate growth of ice sheets in the Northern Hemisphere. After the mid-Pleistocene transition (~0.9 Ma), the occurrence of grain size changes related to precessional cycles within the long-term glacial periods did not appear in our modeling results. Such variations may thus represent changes of the dust source areas controlled by the East Asian summer monsoon. However, the suppression of precessional variations in the major paleosol layers indicates that loess deposits at least in the central CLP are a low time-resolution archive for capturing precession-scale paleoclimatic changes during interglacial periods.

Evidence for strong relations between the upper Tagus loess formation (central Iberia) and the marine atmosphere off the Iberian margin during the last glacial period

AbstractDuring glacial times, the North Atlantic region was affected by serious climate changes corresponding to Dansgaard-Oeschger cycles that were linked to dramatic shifts in sea temperature and moisture transfer to the continents. However, considerable efforts are still needed to understand the effects of these shifts on terrestrial environments. In this context, the Iberian Peninsula is particularly interesting because of its close proximity to the North Atlantic, although the Iberian interior lacks paleoenvironmental information so far because suitable archives are rare. Here we provide an accurate impression of the last glacial environmental developments in central Iberia based on comprehensive investigations using the upper Tagus loess record. A multi-proxy approach revealed that phases of loess formation during Marine Isotope Stage (MIS) 2 (and upper MIS 3) were linked to utmost aridity, coldness, and highest wind strengths in line with the most intense Greenland stadials also including Heinrich Events 3–1. Lack of loess deposition during the global last glacial maximum (LGM) suggests milder conditions, which agrees with less-cold sea surface temperatures (SST) off the Iberian margin. Our results demonstrate that geomorphological system behavior in central Iberia is highly sensitive to North Atlantic SST fluctuations, thus enabling us to reconstruct a detailed hydrological model in relation to marine–atmospheric circulation patterns.

Paleoclimatic changes and modulation of East Asian summer monsoon by high-latitude forcing over the last 130,000 years as revealed by independently dated loess-paleosol sequences on the NE Tibetan Plateau

The variability and interaction of the East Asian summer monsoon (EASM) and mid-latitude Westerlies have dominated Eurasian hydroclimates over orbital timescales and currently influence over a billion lives in Asia. Despite this, the mechanisms influencing EASM-Westerlies variability are still a matter of considerable debate. This study presents three loess-paleosol sequences in the NE Tibetan Plateau (NETP) dated at high-resolution by 50 K-feldspar pIRIR and 37 quartz OSL ages to produce the most detailed chronology for any loess record within the plateau. Combined with this chronology are sedimentology, magnetic susceptibility and grain size analyses with TraCE-21ka climatic modelling to constrain atmospheric controls on climatic changes over the NETP during the past 130 kyr. Our results indicate that deposition initiated by ∼130 ka with especially rapid rates during glacial periods, with maximum rates (140–180 g/cm2/ka) in early MIS 2. Over interglacial-glacial cycles, NETP climatic changes are consistent with warm-moist interglacial and cold-dry glacial conditions recorded in the monsoonal Chinese Loess Plateau and Westerlies-dominated Central Asia but anti-phase to Central Asia during interglacial and the Holocene substages. These results highlight how variation in EASM intensity strongly controls NETP moisture changes but that Holocene and last interglacial changes recorded in the NETP consistently lag 30°N summer insolation by 2–6 kyr. This study suggests high-latitude forcing effectively modulates EASM intensity and that factors such as ice volume, greenhouse gases, and freshwater input to northern Atlantic and Southern oceans critically influence NETP paleoclimatic conditions.

New insights on sources contributing dust to the loess record of the western edge of the Pampean Plain during the transition from the late MIS 2 to the early Holocene

High-resolution studies of palaeorecords located closer to the dust source areas of South America are relevant for increasing the knowledge on past climatic conditions in the Southern Hemisphere. In this sense, the Pampean loess archives can offer explicit records of dust source, transport, and deposition in the region, providing new insights which may be used to better understand the role of dust in future climate change scenarios. In this work, we studied a loess sequence located at the westernmost Pampean Plain. The studied sequence covers a span of time from the late Marine Isotope Stage (MIS 2) period up to the early Holocene. Loess samples from this record have two grain-size populations, indicating more than one dust source area. The dominance of a coarse-silt subpopulation during the transition from the late MIS 2 to the early Holocene suggests that proximal dust sources were dominant at that time. Two of the most proximal dust sources were analyzed as probable contributors to the Lozada site: sediments derived from the Eastern Pampean Ranges and sediments derived from the shorelines of the Mar Chiquita Lake. The geochemical data suggest that neither area was a significant dust source to the eastern Pampean Plain during the studied interval. Instead, our geochemical data suggest a dominant supply from a southern and relatively closer area, linked to the foothills of the Andes, and the increased activation during the early Holocene of a more distant source to the north in the Puna region, which contributed finer loess.

Climate deteriorations and Neanderthal demise in interior Iberia

Time and circumstances for the disappearance of Neanderthals and its relationship with the advent of Modern Humans are not yet sufficiently resolved, especially in case of the Iberian Peninsula. Reconstructing palaeoenvironmental conditions during the last glacial period is crucial to clarifying whether climate deteriorations or competition and contacts with Modern Humans played the pivotal role in driving Neanderthals to extinction. A high-resolution loess record from the Upper Tagus Basin in central Spain demonstrates that the Neanderthal abandonment of inner Iberian territories 42 kyr ago coincided with the evolvement of hostile environmental conditions, while archaeological evidence testifies that this desertion took place regardless of modern humans’ activities. According to stratigraphic findings and stable isotope analyses, this period corresponded to the driest environmental conditions of the last glacial apart from an even drier period linked to Heinrich Stadial 3. Our results show that during Marine Isotope Stages (MIS) 4 and 2 climate deteriorations in interior Iberia temporally coincided with northern hemisphere cold periods (Heinrich stadials). Solely during the middle MIS 3, in a period surrounding 42 kyr ago, this relation seems not straightforward, which may demonstrate the complexity of terrestrial climate conditions during glacial periods.