Loess accumulation during the last glacial maximum: Evidence from Urluia, southeastern Romania

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Abstract

The Eastern European loess steppe represents one of the most substantial landform types on the continent, yet the impact on this region of the last glacial maximum (LGM), the coldest climatic episode during the last full glacial cycle, is relatively poorly understood. This is in part due to the comparatively small number of sites which have been reliably dated, and in part due to the need to better elucidate depositional models for loess environments at both local and regional scales. Here we present a high-frequency age–depth profile for the last 40 ky from a loess deposit at Urluia in southeastern Romania, using fine-grained quartz optically stimulated luminescence (OSL) dating and environmental magnetism analyses.

Loess accumulation at the site for this period is well constrained by a clearly identifiable tephra deposit corresponding to the ca. 39 ka Campanian Ignimbrite. We show that the tephra is directly overlain by a relatively thin layer of loess corresponding to marine isotope stage (MIS) 3, which is partially overprinted by a weakly developed paleosol. The sequence is dominated by a 6–8 m package of primary loess of LGM age. The eight OSL samples from this package group together around a mean age of 21.6 ± 1.5 ka, and suggest rapid and substantial deposition during this phase. The uppermost part of the section indicates significantly reduced loess accumulation, during the deglacial period into the Holocene, less than 2 m in total thickness. The rapid accumulation of loess during the LGM at Urluia is consistent with increased sedimentation at other loess profiles in the Lower Danube basin, although the variable thickness of these deposits across the catchment highlights the need to more explicitly investigate depositional models for loess. The Urluia record complements emerging data which suggests that the Lower Danube loess steppe was cold, dry and windy during the LGM, yet experienced milder climates than comparable latitudes further west and north, and did not undergo periglacial activity.

Introduction

The Last Glacial Maximum (LGM) is globally recognised as the coldest climatic episode during the last full glacial cycle, and took place from approximately 26.5–19 ka, peaking towards 20 ka (Clark et al., 2009). The LGM is broadly characterised by a global sea-surface temperature minimum (Barrows and Juggins, 2005, Clark et al., 2009, Waelbroeck et al., 2009); maximum ice sheet extent in both polar regions (CLIMAP, 1976, CLIMAP, 1981, Svendsen et al., 2004, Golledge et al., 2012); worldwide sea level decrease of approximately 120 m (Yokoyama et al., 2000, Lambeck and Chappell, 2001, Siddall et al., 2003); the most recent major glacial advances in high altitude regions (Barrows et al., 2002, Ivy-Ochs et al., 2006, Blard et al., 2007, Zech et al., 2008, Barrows et al., 2011, Ehlers et al., 2011, Owen et al., 2012); and the intensification of aeolian activity both in deserts (Fitzsimmons et al., 2007, Singhvi et al., 2010, Roskin et al., 2011, Tripaldi et al., 2011), and in the semi-arid loess steppe downstream and downwind of major glaciated zones (Liu and Ding, 1998, Roberts et al., 2003, Antoine et al., 2009b).

In Europe, the LGM-age, so-called late Weichselian (or Würmian) Glaciation experienced temperature reduction of 5–10 °C (Strandberg et al., 2011), and a possible decrease in precipitation of up to 60% (Peyron et al., 1998, Heyman et al., 2013). These conditions triggered considerable changes in both landscapes and ecosystems across the continent (Fig. 1). The European LGM saw southward expansion of the British–Irish and Scandinavian ice sheets as far as approximately 52°N (Svendsen et al., 2004), substantial glacial advances in the highlands of the Alps, Pyrenees, Carpathians and Balkans (Reuther et al., 2007, Delmas et al., 2008, Ivy-Ochs et al., 2008, Kuhlemann et al., 2009, Hughes et al., 2011, Makos et al., 2012), and the southerly expansion of the zone of periglacial permafrost activity to 45°N in western Europe (Renssen and Vandenberghe, 2003, Bertran and Fabre, 2005) and into the Pannonian Basin of Hungary (Kovács et al., 2007, Fábián et al., 2009). This occurred in conjunction with a proposed southward expansion of tundra and boreal forest conditions (Frenzel, 1992, Svenning et al., 2008), and the coeval retreat of more temperate floral and faunal species into hypothesised climate refugia such as southern and eastern Europe (Bennett et al., 1991, Willis et al., 2000, Willis and van Andel, 2004). However, while substantial work has been undertaken to characterise LGM changes in Europe across the western, central and southern parts of the continent (Allen et al., 1999, Frechen et al., 2003, Sima et al., 2009, Antoine et al., 2009b), comparatively little attention has been given to the effects of this significant cold phase on the extensive loess steppe of eastern Europe.

The eastern European loess steppe extends from lower Austria, across the Danube River and Pannonian basins to the Romanian and Bulgarian Black Sea coast (Haase et al., 2007). Geomorphologically, it represents one of the most substantial landscape zones in Europe, and forms a broadly continuous zone ranging across the Russian Plain into central Asia and China. The eastern European loess deposits represent some of the most comprehensive terrestrial palaeoenvironmental records on the continent, extending to at least 1 Ma (Markovič et al., 2011). The eastern European loess archives correlate not only regionally (Markovič et al., 2008, Fitzsimmons et al., 2012) but also across Eurasia into China (Fitzsimmons et al., 2012, Markovič et al., 2012, Buggle et al., 2013). The relatively continuous loess deposits have remained uninterrupted by direct glaciation and periglacial conditions throughout their history, but nevertheless reflect oscillations between relatively cold-dry (glacial loess) and warm-humid (interglacial paleosols) phases (Fitzsimmons et al., 2012). Recent intensification of scientific investigation in the region has seen valuable longer-term reconstruction of palaeoclimatic and palaeoenvironmental change (e.g. Jordanova et al., 2008, Buggle et al., 2009, Markovič et al., 2009, Markovič et al., 2011). However, at this stage, relatively little is explicitly known about the impact of LGM cold conditions in eastern Europe. Several estimates of LGM temperatures in the Pannonian Basin is Hungary suggest cooling of mean annual temperatures in the range of 2–9 °C (Varsányi et al., 2011, Kovács et al., 2012). It has been proposed that the cooler phase of Marine Isotope Stage (MIS) 2, corresponding to the uppermost L1L1 stratigraphic unit in the loess (Markovič et al., 2008), saw the highest rates of loess accumulation over the last million years (Frechen et al., 1997, Fuchs et al., 2008, Újvári et al., 2010), associated with cold, dry, windy conditions (Haesaerts et al., 2003, Antoine et al., 2009a, Stevens et al., 2011). Malacological evidence from Hungarian (Sümegi and Krolopp, 2002, Sümegi et al., 2011) and Serbian (Markovič et al., 2004, Markovič et al., 2006) loess likewise suggests an intensification of cold, steppic conditions during MIS 2, although conditions may have been comparatively warmer than further west, resulting in the establishment of refugia for thermophilic flora and fauna as far north as Hungary (Willis et al., 2000). As yet, however, there exist very few LGM age estimates from the L1L1 loess. Consequently, it has not been possible to directly assess loess accumulation rates during the LGM compared with rates during MIS 3, early MIS 2 and the Holocene.

In this paper we present a high-frequency age–depth profile from a loess deposit at Urluia, southeastern Romania, extending from the MIS 3-age L1S1 paleosol complex to the present S0 Holocene soil, in order to reconstruct LGM conditions in the eastern European loess steppe. A tephra deposit, confirmed to derive from the Campanian Ignimbrite (CI) eruption (39.28 ± 0.11 ka; De Vivo et al., 2001), underlies this sequence (Fitzsimmons et al., 2013) and provides a known-age, maximum constraint for our study. Our chronology is established by direct dating of the fine-grained quartz component using optically stimulated luminescence (OSL) dating, which measures when sediments were last exposed to sunlight (Aitken, 1998). Environmental variations down the sequence are qualified for intensity using environmental magnetism (Hambach et al., 2008). Environmental magnetism in loess is based on the principle of enhancement of magnetic minerals derived from silicate minerals through pedogenesis; variations are therefore climatically controlled, and reflect glacial–interglacial and stadial–interstadial contrasts (Hambach et al., 2008). The two methods combined, targeting the L1L1 stratigraphic unit, provide us with the first direct assessment of environmental conditions and loess accumulation rates in the eastern European loess steppe during MIS 2, and specifically the LGM. The results have implications for depositional models in loess during periods of particularly high accumulation rates.

Section snippets

Regional setting

The loess deposits of the middle and lower Danube River basin represent the most substantial terrestrial recorders of palaeoenvironmental change on the European continent (Markovič et al., 2008, Fitzsimmons et al., 2012). The loess deposits are derived primarily from aeolian transport of fluvial silts associated with glaciers in the Danube catchment headwaters (Smalley and Leach, 1978, Buggle et al., 2008, Újvári et al., 2008), with minor further-travelled contributions from the Russian Plain

Methods

The profile at Urluia was cleaned and logged at six subsections (Fig. 2B), with the aim of documenting sedimentary characteristics and soil development. Two of these subsections (5 and 6) include the exposure of CI tephra and have been described previously (Fitzsimmons et al., 2013).

Sediment samples for environmental magnetism analyses were collected from the cleaned sections at intervals either of 10 cm or 5 cm (see Table S1, Supplementary Information). A total of 222 samples were collected

Stratigraphy and environmental magnetism

This paper investigates the chronostratigraphy of the loess deposit overlying the CI tephra at the Urluia site. The stratigraphy and magnetic susceptibility results are summarised in Fig. 3, and show that the majority of the post-CI deposit is dominated by primary beige-coloured loess deposits corresponding to the L1L1 unit, as defined by the eastern European loess stratigraphic scheme (Markovič et al., 2008, Fitzsimmons et al., 2013). A weakly developed soil and underlying primary loess are

Reviewing the depositional model for loess accumulation in the Lower Danube basin

The rapid accumulation of loess over the LGM period at Urluia is consistent with increased sedimentation rates at this time at loess profiles elsewhere in the Lower Danube basin, at Süttő (Novothny et al., 2009), Surduk (Fuchs et al., 2008) and Crvenka (Stevens et al., 2011). However, the fact that accumulation rates do not increase at other loess sites in the region, irrespective of aspect relative to the alluvial source and prevailing wind direction, such as at Stari Slankamen (Schmidt et al,

Conclusions

The loess profile at Urluia, southeastern Romania, exposes one of the most substantial deposits of post-40 ka loess in the Lower Danube basin. The presence of the known-age, ca. 39 ka CI tephra provides an excellent upper limit for the investigation of LGM loess accumulation. In this study we provide a high-frequency age–depth profile for this upper part of the sequence, using fine-grain quartz OSL and magnetic susceptibility measurements. Dating measurements were undertaken independently on

Acknowledgements

Research for the Lower Danube Survey for Palaeolithic Sites (LoDanS) project was funded by the Max Planck Institute for Evolutionary Anthropology (MPI-EVA). The authors thank Professor J.-J. Hublin and Dr. S. McPherron (MPI-EVA) for their support. Thanks to Dr S. McPherron (MPI-EVA) for help with the surveying by total station and to R. Ioviţă for making sense of those data. Thanks to S. Albert (MPI-EVA) for assistance with OSL sample preparation. We wish to thank R. Ioviţă, A. Doboş and A.

References (118)

  • B. Buggle et al.

    Geochemical characterization and origin of Southeastern and Eastern European loesses (Serbia, Romania, Ukraine)

    Quaternary Science Reviews

    (2008)
  • B. Buggle et al.

    Stratigraphy, and spatial and temporal paleoclimatic trends in Southeastern/Eastern European loess–paleosol sequences

    Quaternary International

    (2009)
  • D. Constantin et al.

    SAR-OSL dating of different grain-sized quartz from a sedimentary section in southern Romania interbedding the Campanian Ignimbrite/Y5 ash layer

    Quaternary Geochronology

    (2012)
  • M. Delmas et al.

    Exposure age chronology of the last glaciation in the eastern Pyrenees

    Quaternary Research

    (2008)
  • J. Ehlers et al.

    The extent and chronology of Cenozoic Global Glaciation

    Quaternary International

    (2007)
  • K. Fitzsimmons et al.

    Pleistocene environmental dynamics recorded in the loess of the middle and lower Danube basin

    Quaternary Science Reviews

    (2012)
  • K.E. Fitzsimmons et al.

    The timing of linear dune activity in the Strzelecki and Tirari Deserts, Australia

    Quaternary Science Reviews

    (2007)
  • M. Frechen et al.

    Geochronology of middle and upper Pleistocene loess sections in Hungary

    Quaternary Research

    (1997)
  • M. Frechen et al.

    Loess in Europe – mass accumulation rates during the Last Glacial Period

    Quaternary Science Reviews

    (2003)
  • D. Haase et al.

    Loess in Europe – its spatial distribution based on a European Loess Map, scale 1:2,500,000

    Quaternary Science Reviews

    (2007)
  • P. Haesaerts et al.

    Charcoal and wood remains for radiocarbon dating Upper Pleistocene loess sequences in Eastern Europe and Central Siberia

    Palaeogeography, Palaeoclimatology, Palaeoecology

    (2010)
  • B.M. Heyman et al.

    Paleo-climate of the central European uplands during the last glacial maximum based on glacier mass-balance modeling

    Quaternary Research

    (2013)
  • P.D. Hughes et al.

    The glacial history of the Dinaric Alps, Montenegro

    Quaternary Science Reviews

    (2011)
  • D. Jordanova et al.

    Palaeomagnetism of the loess/palaeosol sequence in Viatovo (NE Bulgaria) in the Danube basin

    Physics of the Earth and Planetary Interiors

    (2008)
  • D. Karátson et al.

    Morphometrical and geochronological constraints on the youngest eruptive activity in East-Central Europe at the Ciomadul (Csomád) lava dome complex, East Carpathians

    Journal of Volcanology and Geothermal Research

    (2013)
  • J. Kovács et al.

    Reconstructing the paleoenvironment of East Central Europe in the Late Pleistocene using the oxygen and carbon isotopic signal of tooth in large mammal remains

    Quaternary International

    (2012)
  • N. Mahowald et al.

    Model insight into glacial–interglacial paleodust records

    Quaternary Science Reviews

    (2011)
  • S.B. Markovič et al.

    Middle and Late Pleistocene loess sequences at Batajnica, Vojvodina, Serbia

    Quaternary International

    (2009)
  • S.B. Markovič et al.

    The last million years recorded at the Stari Slankamen (Northern Serbia) loess-palaeosol sequence: revised chronostratigraphy and long-term environmental trends

    Quaternary Science Reviews

    (2011)
  • S.B. Markovič et al.

    An introduction to the Middle and Upper Pleistocene loess–paleosol sequence at Ruma brickyard, Vojvodina, Serbia

    Quaternary International

    (2006)
  • A.S. Murray et al.

    Luminescence dating of quartz using an improved single-aliquot regenerative-dose protocol

    Radiation Measurements

    (2000)
  • Á. Novothny et al.

    Luminescence and amino acid racemization chronology of the loess–paleosol sequence at Sütto, Hungary

    Quaternary International

    (2009)
  • Á. Novothny et al.

    Investigating the penultimate and last glacial cycles of the Sütto loess section (Hungary) using luminescence dating, high-resolution grain size, and magnetic susceptibility data

    Quaternary International

    (2011)
  • L.A. Owen et al.

    Quaternary glaciation of the Tashkurgan Valley, Southeast Pamir

    Quaternary Science Reviews

    (2012)
  • O. Peyron et al.

    Climatic reconstruction in Europe for 18,000 YR B.P. from pollen data

    Quaternary Research

    (1998)
  • J.R. Prescott et al.

    Cosmic ray contributions to dose rates for luminescence and ESR dating: large depths and long term variations

    Radiation Measurements

    (1994)
  • H. Renssen et al.

    Investigation of the relationship between permafrost distribution in NW Europe and extensive winter sea-ice cover in the North Atlantic Ocean during the cold phases of the Last Glaciation

    Quaternary Science Reviews

    (2003)
  • A.U. Reuther et al.

    Late Pleistocene glacial chronology of the Pietrele Valley, Retezat Mountains, Southern Carpathians constrained by 10Be exposure ages and pedological investigations

    Quaternary International

    (2007)
  • H.M. Roberts et al.

    Unprecedented last-glacial mass accumulation rates determined by luminescence dating of loess from western Nebraska

    Quaternary Research

    (2003)
  • A.-K. Schatz et al.

    The late Quaternary loess record of Tokaj, Hungary: reconstructing palaeoenvironment, vegetation and climate using stable C and N isotopes and biomarkers

    Quaternary International

    (2011)
  • E.D. Schmidt et al.

    Luminescence chronology of the upper part of the Stari Slankamen loess sequence (Vojvodina, Serbia)

    Quaternary Geochronology

    (2010)
  • A. Sima et al.

    Imprint of North-Atlantic abrupt climate changes on western European loess deposits as viewed in a dust emission model

    Quaternary Science Reviews

    (2009)
  • A.K. Singhvi et al.

    A ∼200 ka record of climatic change and dune activity in the Thar Desert, India

    Quaternary Science Reviews

    (2010)
  • I. Smalley et al.

    Rivers and loess: the significance of long river transportation in the complex event-sequence approach to loess deposit formation

    Quaternary International

    (2009)
  • I.J. Smalley et al.

    The origin and distribution of the loess in the Danube basin and associated regions of East-Central Europe – a review

    Sedimentary Geology

    (1978)
  • T. Stevens et al.

    Dust deposition and climate in the Carpathian Basin over an independently dated last glacial–interglacial cycle

    Quaternary Science Reviews

    (2011)
  • J.-B. Stuut et al.

    Aeolian dust in Europe: African sources and European deposits

    Quaternary International

    (2009)
  • E. Stworzewicz et al.

    Malacological and palynological evidence of the Lower Pleistocene cold phase at the Carpathian Foothills (Southern Poland)

    Quaternary Research

    (2012)
  • P. Sümegi et al.

    The loess–paleosol sequence of Basaharc (Hungary) revisited: mollusc-based paleoecological results for the Middle and Upper Pleistocene

    Quaternary International

    (2011)
  • P. Sümegi et al.

    Quatermalacological analyses for modeling of the Upper Weichselian palaeoenvironmental changes in the Carpathian Basin

    Quaternary International

    (2002)
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      During the last glacial period the Danube region is thought to have predominantly experienced mostly steppic, continental climates (Marković et al., 2018b; Zech et al., 2013), with conditions too dry to sustain short-term pedogenesis (Marković et al., 2015). This resulted in “classic” loess profiles, comprising thick glacial loess units, separated by well-developed interglacial palaeosols and, at some sites, weakly developed interstadial palaeosols (Buggle et al., 2009; Fitzsimmons and Hambach, 2014; Fuchs et al., 2008; Marković et al., 2009; Vasiliniuc et al., 2011). These classic loess-palaeosol sequences are typically located in a plateau setting and can be linked to large-scale, orbitally driven climate changes (Zeeden et al., 2018b).

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