Loess Sequences Research Articles

Three climatic cycles recorded in a loess-palaeosol sequence at Semlac (Romania) – Implications for dust accumulation in south-eastern Europe

Recent inve\stigations of the Semlac loess section in the south-eastern Carpathian Basin, which is situated at an undercut slope position on the right bank of the Mures River in its lower reaches (Banat region, western Romanian), are presented and discussed. Dating back to marine isotope stage (MIS) 10, the more than 10 m thick loess sequence includes four fossil soil-complexes developed in homogenous and relatively fine silty loess. Because of the good preservation of the sediment, Semlac is regarded as a key section for the Carpathian Basin, which offers possibilities to a) improve the understanding of the type and composition (loess homogeneity and pedogenic alteration) of the lowland loess sequences in the Carpathian Basin also beyond the last interglacial palaoesol complex, b) to reconstruct the temporal evolution of the local loess-palaoesol successions, c) gain better insight into the regional paleoenvironments of the last 300ka and d) to compare the loess of the region to loess-sequences in adjacent areas and to dust proxy data in the northern hemisphere. An integrated age model based on correlation to reference records and luminescence dating is compiled. Applying this age model we compare climate proxy data from Semlac to both global data and to data from the very southeast of the Carpathian Basin (Vojvodina, Serbia). The obtained results provide new insight into the dust accumulation regime for the eastern Carpathian Basin and offer new palaeoenvironmental information for the region and are an important step towards establishing 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 south-eastern and central Carpathian Basin. Disentangling grain size data from soil formation proxies is used to investigate patterns of non-local dust. Patterns of non-pedogenetic fine material are similar to grain size proxies from China and other parts of the northern hemisphere, suggesting western and eastern Eurasian loess to have (at least partly) similar mechanistic/climatic origins. (C) 2016 Elsevier Ltd. All rights reserved.

Tracing the influence of Mediterranean climate on Southeastern Europe during the past 350,000 years.

Loess-palaeosol sequences are valuable archives of past environmental changes. Although regional palaeoclimatic trends and conditions in Southeastern Europe have been inferred from loess sequences, large scale forcing mechanisms responsible for their formation have yet to be determined. Southeastern Europe is a climatically sensitive region, existing under the strong influence of both Mediterranean and continental climates. Establishment of the spatial and temporal evolution and interaction of these climatic areas is essential to understand the mechanisms of loess formation. Here we present high-resolution grain-size, environmental magnetic, spectrophotometric and geochemical data from the Stalać section in the Central Balkans (Serbia) for the past ~350,000 years. The goal of this study is to determine the influence of the Mediterranean climate during this period. Data show that the Central Balkans were under different atmospheric circulation regimes, especially during Marine Isotope Stages 9 and 7, while continental climate prevailed further north. We observe a general weakening of the Mediterranean climate influence with time. Our data suggest that Marine Isotope Stage 5 was the first interglacial in the Central Balkans that had continental climate characteristics. This prominent shift in climatic conditions resulted in unexpectedly warm and humid conditions during the last glacial.

Origin and weathering of landslide material in a loess area: a geochemical study of the Kulcs landslide, Hungary

Geochemical characteristics of sediments are responses to physical and chemical alteration in landslides. However, consequences of in situ interactions associated with landslides are difficult to distinguish from those related to long-term weathering in young soft sediments such as loess. In this study, geochemical characteristics of the Kulcs landslide in Hungary are studied to identify the provenance of the loess–paleosol–red clay sequence and geochemical signatures that can potentially be attributed to the effects of landsliding. Results indicate that sliding is largely initiated by the lithological changes within the landslide body. Sediments above the sliding zone closely resemble the non-slipped Pleistocene old loess deposits from Hungary. It is also confirmed that the sliding zone develops in old paleosols in the loess sequence and red clays at its base which are all characterized by the enrichment of Al, K, Na, H2O and considerable depletion in Ca and Mg associated with carbonates. Altogether, these geochemical characteristics indicate that chemical weathering trend of unconsolidated landslide sediments is slightly modified by the redistribution of carbonates and decomposition of plagioclase. It is assumed that the distribution of Mn and Ba is modified by the water–sediment interaction in the landslide.

Palaeoenvironment and dating of the Early Acheulean localities from the Somme River basin (Northern France): New discoveries from the High Terrace at Abbeville-Carrière Carpentier

Dating the earliest human occupations in Western Europe and reconstructing links with climatic and environmental constraints is a central issue in Quaternary studies. Amongst the discovery of Palaeolithic artefacts ascribed to the Early Pleistocene in southeast Britain and central France the Somme Basin, where the Acheulean type-site Amiens Saint-Acheul is located, is a key area for addressing this topic. Research undertaken over the past 20 years on both Quaternary fluvial and loess sequences of this area has provided a unique dataset for the study of the relations between human occupations and environmental variations. Studies based on an interdisciplinary approach combining sedimentology, palaeontology and geochronology have highlighted the impact of the 100 kyrs cycles on terrace formation during the last million years. In this terrace system, the earliest in situ Acheulean settlements known in the 1990s were dated to early MIS 12 (±450 ka), but new field discoveries, at Amiens “Rue du Manege”, dated to ± 550 ka, significantly increase the age of the oldest human occupation in the area. In this context, new fieldwork has been undertaken in Abbeville at the Carriere Carpentier site, famous for its White Marl deposit attributed to the Cromerian and in the same terrace level where the former discoveries of “Abbevillian bifaces” were made by d'Ault du Mesnil. This research is based on an interdisciplinary approach, combining sedimentology, paleontology, dating (ESR on quartz and ESR/U-series on teeth) and archaeology. According to the various bio-proxies (molluscs, large vertebrates, small mammals), the White Marl was deposited during the early part of an interglacial phase in an aquatic slow-flowing environment, as emphasized by the development of oncoliths and the presence of fish and aquatic molluscs. The landscape was composed of a mosaic of open bush and forest areas, in which wet and grassy vegetation developed on riverbanks. On the basis of terrace stratigraphy, ESR and ESR/U-series dating results, and biostratigraphic data, the fluvial deposits of the White Marl can be securely attributed to MIS 15. In addition, some Acheulean bifaces were discovered at the base of the slope deposits, directly overlying the fluvial sequence. These artefacts are most likely coeval with the end of MIS 15 or an early stage of MIS 14, between 550 and 500 ka, and represent, together with the artefacts from Amiens “Rue du Manege”, the oldest in situ evidence of Acheulean occupation in Northern France. However, no unquestionable artefacts have been discovered in the White Marl or in the underlying gravel layer. These discoveries contribute to the chronology of the earliest evidence of hominin occupations in north-western Europe which may be related to Homo heidelbergensis.

MIS3 paleosols in the center-north of Eastern Europe and Western Siberia: Reductomorphic pedogenesis conditioned by permafrost?

The MIS3 paleosol units comprise a prominent element of the loess-paleosol sequences throughout the Eurasian Loess Belt. To the north of the loess regions, the findings of MIS3 paleosols were few: it was supposed that geomorphic processes related to the extensive ice cover of the Last Glacial Maximum destroyed the earlier soil mantle. Recently, much smaller extent of continental ice in the east of Northern Europe and ice-free West Siberian Plain during MIS2 has been hypothesized, supposing preservation of MIS3 and earlier paleopedological records. We discovered in the center-north of European Russia (Upper Volga basin) and Western Siberia (Middle Ob basin), MIS3 paleosols within the Late Pleistocene alluvial and lacustrine sequences and correlated the studied profiles on the basis of macro- and micromorphological characteristics and radiocarbon datings of the paleosol organic materials. Paleosols are represented by hydromorphic profiles with Histic horizons and gleyic color pattern. Conspicuously, they are developed in the well drained geomorphic positions, where modern soils are non-gleyic. We suppose that the presence of permafrost was responsible for water logging and generation of reductomorphic soil environment. We further hypothesize a northern zone of MIS3 soil mantle, comprised of Histic and Reductaquic Cryosols different from synchronous Cambisols and Chernozems formed within loess sequences to the south.

Paleoenvironmental changes recorded in a luminescence dated loess/paleosol sequence from the Tianshan Mountains, arid central Asia, since the Penultimate Glaciation

Mid-latitude arid central Asia (ACA) is one of the driest regions in the world and is a key source area of global atmospheric dust. Loess records of paleoclimatic changes in ACA are complex and interpretations are problematic due primarily to the lack of robust chronologies. Quartz OSL and K-feldspar pIRIR dating methods were employed to date 8 quartz and 30 K-feldspar samples from a 30 m loess sequence (BYH10 section) on the northern slope of the Tianshan Mountains, central ACA, northwest China. The reliability of quartz and K-feldspar ages was monitored by internal checks of luminescence characteristics and by comparison of the quartz and K-feldspar ages. The section lithology, proxy indexes of grain size and magnetic susceptibility, and the high resolution OSL chronology together indicate: (1) Quartz OSL dating can be used to date ACA loess samples less than 40 ka, while K-feldspar pIRIR dating is reliable for loess samples at least as old as ∼150 ka from ACA; (2) Aeolian loess began to be deposited on the northern slope of Tianshan Mountains beginning at least ∼145 ka ago, and was deposited primarily during the penultimate and last glaciation periods; (3) Rapid loess deposition occurred during MIS 6, MIS 4 to early-mid MIS 3, and MIS 2, but little or no loess deposition occurred during MIS 5, MIS 3a and MIS 1; (4) This loess depositional sequence is comparable to previously published stalagmite growth records in the region on glacial-interglacial cycles. Rapid dust deposition and lack of stalagmite growth during glacials, and lack of loess deposition and stalagmite growth during interglacials, indicate a climatic pattern of wet-warm (interglacial) and dry-cold (glacial) climatic regimes on orbital cycles in ACA; (5) Variation in the loess deposition rates in ACA was much larger than in the central loess plateau during the last glaciation; (6) Depositional hiatuses of >50 kyr occur in ACA loess sequences, and high resolution chronologies are needed when reconstructing past climatic changes.

The Late Pleistocene loess-palaeosol sequence of Middle Belgium

In Belgium, two areas show extended Late Pleistocene loess cover: the Hesbaye close to Liège and the Haine Basin around Mons. For decades, correlation between both areas remained problematic. Here we will show how, by way of complementary approaches, the records of the Haine and the Hesbaye could be inserted into a high resolution pedosedimentary sequence encompassing the major part of the Late Pleistocene and reproducible at the scale of the Belgian loess belt. Based on the pedosedimentary and palaeoenvironmental signatures of the Belgian sequence, comparisons are proposed with high resolution loess sequences of Eastern Europe and Central Siberia. They give access to well documented palynological data for the first part of the Late Pleistocene and to a strong climatic record on loess framed between 45 and 10 ka BP by long series of radiocarbon dates on charcoal and wood remains. The conjunction of these complementary loess records has further given way to a consistent proxy-correlation scheme linking a high resolution continental climatic record to the Greenland ice sequence.

Soil nitrogen isotopic composition of the Xifeng loess-paleosol sequence and its potential for use as a paleoenvironmental proxy

The isotopic composition of soil nitrogen (soil δ15N values) has been widely used to explore the soil biogeochemical cycle and study land vegetation conditions. However, the δ15N values in the loess-paleosol sequence have not been thoroughly studied. In this study, we provide the first report of δ15N values from the Xifeng loess-paleosol profile, which spans the last 130 ka. The δ15N values show great variation (2.1‰–6.1‰) in the Xifeng loess sequence. According to these results, the δ15N values have a similar pattern with changes in the magnetic susceptibility (MS) and exhibit significant differences within the glacial-interglacial cycle over the last 130 ka. We hypothesize that climate conditions and land vegetation conversion could be reflected by the changes in the δ15N values within the glacial-interglacial cycle. (1) The δ15N values are positively correlated with the reconstructed mean annual temperature (MAT) and mean annual precipitation (MAP) on the glacial-interglacial time scale. Moreover, it appears that the MAT may be more effective than the MAP for the δ15N changes in the Xifeng loess-paleosol sequence. (2) Vegetation changing from grasses to shrubs may cause 15N depletion during the glacial period. In addition, increasing grass groups may cause 15N enrichment of the soil during the interglacial stage in the Xifeng loess-paleosol sequence. Because nitrogen is one of the most significant nutrient elements for vegetation, paleovegetation changes may be the main controlling factor for δ15N values in the loess-paleosol section. Therefore, δ15N values have the potential for use as a proxy in paleoenvironmental reconstructions of the Chinese Loess Plateau.

First results from the Late Pleistocene paleosols in northern Western Siberia: Implications for pedogenesis and landscape evolution at the end of MIS3

Recent revision of the extent of Late Pleistocene glaciations in Northern Eurasia the justified search for the new paleopedological records in the center-north West Siberian Plain. We encountered paleosols in several exposures of the high alluvial terrace of the river Vakh (Middle Ob' basin), buried in the sequence of alluvial and lacustrine sediments. A paleosol dated to the end of Marine Isotope Stage (MIS) 3, Karga thermochron, was studied in detail in the key section “Zeleniy Ostrov”. The paleosol demonstrates strong morphological evidence of gleysation and accumulation of plant residues, both processes indicating water logging and a reduced environment. The modern soil on top of the exposure is a typical Podzol, formed in under conditions of perfect soil drainage and no water excess, in agreement with current geological and geomorphological conditions. We suppose that permafrost was the main factor hampering percolation and switching redoximorphic processes in the paleosol, which thus was classified as a Reductaquic Cryosol. Presence of permafrost implies colder climate than the present one. Furthermore, neutral reaction, presence of neoformed calcium carbonate and abundance of silt fraction, which points to eolian sedimentation, suggest drier conditions. However, the studied paleosols differ considerably from the synchronous Chernozems found in the loess sequences of Southern Siberia. Paleobiological proxies such as pollen, plant macroremains, phytoliths and fossil insects indicate a tundra or tundra-steppe ecosystem (possibly with some forest stands), in good agreement with the paleopedological and sedimentary records.

Determining surface magnetic susceptibility of loess-paleosol sections based on spectral features: Application to a UHD 185 hyperspectral image

Magnetic susceptibility (MS) records of loess-paleosol sequences have been considered a measure of the degree of pedogenic activity and are considered to be excellent proxies for terrestrial climatic fluctuations. However, the MS of single (vertical) path variations occasionally represents site-specific influences rather than monsoonal changes (depending on the position of the path). Few studies have used remote sensing techniques to map the surface MS information of loess-paleosol sections. Hyperspectral techniques provide an efficient, economical and quantitative alternative. In this study, stepwise regression was used to build MS estimation models based on spectral features. Six MS models based on spectral features were established. Test datasets indicated that our models are very successful, all resulting in R2>0.92 and RMSEs ranging from 4.5736 to 6.80475. The slope change between 810nm and 880nm (b880/b810) observed in all models played an important role in MS estimation. Models 5 and 6 have higher RMSEs and relatively lower SAM values, although the R2 values are both above 0.95. The RMSEs of the first four models are similar. Therefore, the first four models were thought to be more stable and useful.UHD 185, a new generation of commercial hyperspectral imaging sensor, was used for surface MS mapping of a loess-paleosol section by model 1 and model 2. The MS map corresponded well to the loess sequences. The MS values obtained from the UHD 185 data are convincing and consistent with the measured data (R2>0.85). The trend in changing MS values is clear, suggesting that model 1 and model 2 could produce reasonable loess-paleosol section surface maps from the UHD 185 image, although there is a linear offset between the estimated MS and the measured MS. The methodology proposed here can be used to map MS on a much larger scale. Because of the limit of the spectral range, the performances of model 3 and model 4 with the image were not discussed. However, they have been shown to be successful according to the laboratory test data.

High‐resolution scanning XRF investigation of Chinese loess and its implications for millennial‐scale monsoon variability

ABSTRACTMillennial‐scale monsoon variability has been investigated intensively using loess‐based proxies; however, the amplitude and rhythms of millennial‐scale signals have seldom been disentangled from the background glacial–interglacial changes. Here we present the results of high‐resolution scanning X‐ray fluorescence analysis of a 75‐m‐thick loess sequence from the north‐western Chinese Loess Plateau to address glacial–interglacial to millennial monsoon variability over the last two climatic cycles. Variations of the Si/K, Fe/K and Ca/K ratios are separated spectrally into low‐ and high‐frequency components corresponding to glacial–interglacial and millennial‐scale monsoon variability, respectively. The results indicate that the three elemental ratios exhibit similar glacial–interglacial variability but with varying spectral densities at the 100‐, 41‐ and 23‐kyr periodicities. Millennial‐scale variability is quite similar between the three elemental ratios, and comparable to those inferred from records of Chinese speleothem δ18O, Greenland palaeotemperature and North Atlantic cooling events. Comparison of various proxies indicates the broad similar magnitudes of abrupt climate changes, at least during the last two glacial–interglacial cycles, whereas the timing and amplitude of abrupt climatic events are not well correlated. We suggest that refinement of loess chronology and intensive data‐model integration in the future are critical to decipher the characteristics and dynamics of rapid monsoon changes.

Three climatic cycles recorded in a loess-palaeosol sequence at Semlac (Romania) - implications for dust accumulation in the Carpathian Basin and the northern Hemisphere

Semlac is regarded as a key section for the Carpathian Basin because of the good preservation of the fine silt. The site is situated at the Mures River in its lower reaches (Banat region, western Romanian). The more than 10 m thick loess sequence includes four fossil sol-complexes developed in homogenous relatively fine silty loess and dates back to marine isotope stage (MIS) 10. This setting offers possibilities to a) improve the understanding of the type and composition of the lowland loess sequences in the Carpathian Basin for the last interglacial palaeosol complex and beyond, b) reconstruct the temporal evolution of the local loess-palaeosol successions and c) compare the loess of the region to loess-sequences in adjacent areas (Carpathian Basin, Lower Danube) and to dust proxy data in the northern hemisphere. A strikingly sinusoidal course of physical property data in depth and time point to relatively homogenous, quasi-continuous background sedimentation of dust, which are interpreted as resulting from long-range transport. This is in contrast to a commonly observed more glacial-interglacial pattern with sharp boundaries of paleosols

The Agh Band loess-palaeosol sequence – A terrestrial archive for climatic shifts during the last and penultimate glacial–interglacial cycles in a semiarid region in northern Iran

Abstract The Northern Iranian loess profiles host important information on Quaternary climate and palaeoenvironmental changes in the region. They build an important link between the Eurasian loess belt and European and Central Asian archives. Due to a climatic gradient with decreasing precipitation from the west to the east and from the south to the north, loess-palaeosol sequences formed synchronously under different climatic conditions can be studied over short distance in the Iranian Caspian Lowland. The Agh Band profile is located in the so called Iranian “Loess Plateau”, a semi-arid region with 200–350 mm annual precipitation. The loess deposits at Agh Band reach a thickness of >60 m. An about 50 m thick step-profile was prepared and the litho/pedostratigraphy was investigated. Samples for laser-diffractometry grain-size measurements were taken every 2 cm. The magnetic susceptibility was measured in 4 cm intervals and the CaCO3-content in 8 cm intervals. To establish a chronological framework a pIRIR290 luminescence dating approach was applied to the 4–11 μm polymineral fraction. The results show that the Agh Band profile yields a climate archive reaching from MIS 7 to MIS 2. Several chronological hiatuses of some 10 ka show that periods of intense loess accumulation were interrupted by phases of only minor loess sedimentation and/or erosion. The Agh Band profile is subdivided by several shifts in grain-size distribution. The coarsening- and fining up trends correlate with increasing and decreasing wind-velocity, respectively. In the central part of the Agh Band loess sequence a weakly developed palaeosol is preserved which was developed at around 80 ka. Furthermore, the loess deposits formed from about 100 ka to 60 ka ago show banded structures. A pedocomplex including two well-developed palaeosols consisting of Bw(y) horizons and a CB-horizon as well as intercalated loess can be found in the lower part of the sequence also evidenced by the increased values of magnetic susceptibility. The corresponding luminescence age estimates indicate that the palaeosols represent a period of increased humidity and landscape stability during late MIS 7 and MIS 6. Hence, in the Agh Band loess, various changes in the palaeo-sedimentary system, triggered by changes in climate can be observed. This yields important information on the sensitive response of sedimentary systems and landscapes within semi-arid regions to shifts in moisture and possibly temperature.

Palaeotemperature reconstruction during the Last Glacial from δ 18 O of earthworm calcite granules from Nussloch loess sequence, Germany

Abstract The Nussloch loess–palaeosol sequence (Rhine Valley, Germany) is considered to be one of the most complete records of the last glacial period in Western Europe due to its very high sedimentation rate and its good chronological control. This sequence is therefore a good framework in which to develop new proxies for palaeoenvironmental reconstructions. In this study, we explore, for the first time, the potential of earthworm calcite granules as a new bio-indicator and climatic proxy of absolute air and soil temperature in the context of Last Glacial loess. These granules are composed of rhomboedric calcite crystals, organized in a radial crystalline structure. As these granules are individually generated by earthworms at a relative fast rate, they are expected to record intra-annual variations in the available sources of oxygen: percolating waters of meteoric origin. We extracted thirty earthworm calcite granules from 11 of 5 cm layers thick from tundra gley and brown soil horizons previously, dated at 45 to 23 ka. Oxygen isotope ratios were measured on each individual granule. The δ18O of calcite granules and interlinked transfer functions between water cycle, air and soil temperatures allowed us to estimate air temperatures ranging from 10 to 12 ± 4 °C , which most likely reflect the warm periods of the year when earthworms were the most active.

VÝZKUM POZDNĚ KVARTÉRNÍ AKTIVITY ZLOMU KOSÍŘE V HORNOMORAVSKÉM ÚVALU ANEB PROČ JE DOBRÉ STUDOVAT SVAHOVINY A SEISMOGRAMY

Preliminary results of a research into the late Quaternary slip of a major fault in the seismically active Upper Morava Basin are given. Three trenches, up to 6 m deep, were excavated at the foot of the Kosíř Fault scarp near Stařechovice and Čelechovice. The exposed complex sequences of colluvium and loess, now only partly dated by OSL and 14C, is heavily faulted. The faulting is explained by a tectonic slip at the Kosíř Fault and, in the Stařechovice trench, also by simultaneous slope deformations. None of the faults do off set the Holocene topsoil but the youngest of them were clearly active aft er the deposition of the youngest loess and indicate the slip of up to 1.4 m in Late Pleistocene. In Čelechovice trenches the minimum vertical throw of 4 m is indicated for the lower part of the sequence with assumed Late Pleistocene age. The geometry of the deformed zone suggests an oblique normal faulting with significant strike-slip component. The sense of shearing in the horizontal plane was not resolved. Minimum tectonic slip rate of 0.1‒0.3 mm/year in Late Pleistocene is suggested but this must be confi rmed by new dating. Our observations reveal surprisingly young and large deformation which may suggest a temporary increase of tectonic activity during Late Pleistocene.

Granulometrical, mineralogical and geochemical characterization of loess deposits in the Tajo Basin

Loess research has the merit of enabling reconstructions of Pleistocene sedimentation dynamics in many parts of the world. However, there is still very few information regarding the occurrence of loess deposits in the Mediterranean area, even though such records may provide a unique opportunity to investigate landscape evolution for a period for which terrestrial archives are very rare in this region. This paper presents the first results of investigations on a loess sequence in the middle Tajo Valley in central Spain. Findings from detailed granulometrical, mineralogical, geochemical, and grain morphological analyses help to give a first overview on character and composition of these deposits. Very high levels of carbonates (∼60%), but also of gypsum, both to large extents of primary origin, indicate the incorporation of material derived from marls and limestone. Furthermore, we found evidence that allows deduction of possible loess proveniences more precisely. Dolomite contents of up to 20% indicate that the Iberian Range might have been an important source area of loess sediments. The fact that these uplands are located to the east seems to be opposed to the common assumption of prevailing west winds for glacial periods. The studied sequence (Paraiso profile) is one of seven sections that have been investigated as part of a programme to reconstruct Upper Pleistocene landscape dynamics in central Spain. In this context, the detailed characterisation of sediment properties is crucial for discussing loess proveniences and sedimentary environments.

Paleoclimatic and paleoenvironmental fluctuations inferred for the Middle and Late Pleniglacial transition and Late Pleniglacial (MIS3/MIS2 and MIS2) based on high-resolution (ca. 35 and 70 years) complex sedimentological and paleoecological data from the

The Katymar brickyard profile, found at the northernmost fringe of the Backa loess plateau, is one of the thickest and best developed last glacial loess sequences of Central Europe. In the present work high resolution (at 2 cm and 4 cm intervals representing ca. 35 and 70 years) magnetic susceptibility, grain-size, LOI, water-solution trace elements measurements and pollen, phytholithic, anthracological and malacological analyses were implemented on samples derived from the 11,5 m profile corresponding to a period between 35,000 and 13,000 cal BP years (from the terminal phase of MIS3 to the end of MIS2).

Detailed characterization of the Late Pleistocene loess sequence stratigraphy of Remicourt (Hesbaye region, Belgium) with cone penetration tests

1. IntroductionLoess is an aeolian deposit characterized by a very well sorted grain size distribution predominantly ranging between 10-50 µm (corresponding to coarse silt from ASTM D2487-06). In its detailed definition of loess, Pecsi (1990, 1995) added that the weight percentage of the silt fraction corresponds to 40-70%. Geologists, geomorphologists and soil scientists usually consider this material as a sedimentary sequence with heterogeneities even at local scale (palaeosols, unconformity surfaces, palaeovalleys...). In addition to preliminary survey works, characterization of loess and resulting interpretations are classically performed by sedimentological (e.g. Antoine et al., 2013; Guo et al., 2013), pedological (e.g. Ding et al., 1999; Schellenberger & Veit, 2006), mineralogical (e.g. Smykatz-Kloss et al., 2004; Pouclet et al., 2008; Pouclet & Juvigne, 2009) and chronostratigraphic (e.g. Buylaert et al., 2008; Roberts, 2008) studies. Results of these studies point out a succession of layers and horizons including removed sediments, eventual tephra (e.g. Pouclet et al., 2008; Pouclet & Juvigne, 2009) and post-depositional processes as palaeosols formation (e.g. Antoine et al., 2013; Guo et al., 2013; Schellenberger & Veit, 2006), redox processes, chemical and mineralogical modifications (e.g. Schellenberger & Veit, 2006). Moreover, loess deposits are very easily erodible, raising the complexity for stratigraphic studies due to the presence of locally eroded layers and

New magnetostratigraphic and pedostratigraphic investigations of loess deposits in north‐east China and their implications for regional environmental change during the Mid‐Pleistocene climatic transition

ABSTRACTLittle is known about the long‐term climatic evolution of north‐eastern (NE) China, because well‐preserved terrestrial paleoenvironmental archives are scarce in this vast region. The extensive loess deposits in the Chifeng region are the thickest and most complete loess–paleosol sequence in NE China, and have significant potential for reconstructing the paleoclimate of the region. Here, we present new high‐resolution magnetostratigraphic results from two loess–paleosol sections in the Chifeng region: the Sanbahuo (SBH) and Toudaojingzi (TDJZ) sections. The results demonstrate that both sections record the Brunhes normal polarity chron and the upper portion of the Matuyama reversed polarity chron. Based on these new results, the base of the TDJZ loess sequence is dated at ca. 1.22 Ma, representing the oldest known loess deposits in NE China. The initiation of loess accumulation in NE China was roughly synchronous with the large expansion of the Eurasian loess belt during the late Early Pleistocene (1.2–0.7 Ma), probably reflecting a widespread intensification of aridity in northern mid‐latitudes. We suggest that global cooling during the Mid‐Pleistocene climatic transition led to increased aridity and more favorable conditions for promoting the availability of silt for entrainment, transport and deposition.

The history of Danube loess research

The loess-paleosol sequences of the Danube basin contain the longest and most complete terrestrial records of Middle and Late Pleistocene paleoclimates in Europe. Consequently it is no surprise that scientific research into European loess began in this region and has a long and distinguished history. European loess research was initiated by Count Marsigli in the Serbian Vojvodina in the late 17th century, formed the focus of the international Loess Commission which straddled both sides of the Iron Curtain from 1961, and culminated with George Kukla's seminal studies in the 1970s correlating the loess archives with deep-sea sediments. The rise in popularity of the longer Chinese loess sequences in the early 1980s shifted the international research focus away from Europe, and it was not until the change of century that scientific investigation intensified in the region – this time with much more sophisticated tools for analysis.Despite its potential as one of Europe's most valuable Quaternary archives, scientific research into Danube loess has until recently been hindered both by landscape heterogeneity and the large number of countries it covers. These have presented a major limiting factor in developing a unified research approach. For decades, regional/national loess stratigraphic models were defined separately. Difficulties in correlating such schemes persist, especially since these often change significantly with advances in dating methodologies. A cooperative effort is necessary to synthesize the available data, which requires not only the insights from but also the perspective provided by an appreciation of the history of the research.In this study we present a critical historical overview of loess research in the Danube region. We classify the major research phases throughout the long tradition of Danube loess investigations into five categories: (1) the Early period (late 17th century until 1920) extending from Marsigli to Penck; (2) the Classic period (1920–1961) encompassing the contributions of Milanković and the development of pedostratigraphy; (3) the Modern period (1961-present) which oversaw Czech innovations and developments in geochronologic methods, in particular Amino Acid Racemisation (AAR) and luminescence dating; and (4) Contemporary research from Bronger's unified pedostratigraphy to orbitally-tuned timescales. Finally, (5) we present a vision of future Danube loess research.