Elsevier

Quaternary Science Reviews

Volume 188, 15 May 2018, Pages 15-27
Quaternary Science Reviews

Dead Sea pollen provides new insights into the paleoenvironment of the southern Levant during MIS 6–5

https://doi.org/10.1016/j.quascirev.2018.03.029Get rights and content

Highlights

  • First high-resolution pollen & charcoal record from the last interglacial Dead Sea.

  • Arboreal and sclerophyllous expansion during the last interglacial optimum.

  • Discrepancies between the Levantine vegetation and Dead Sea lake level.

  • Diverse ecosystems in the southern Levant for the residence of early modern humans.

Abstract

The paleoclimate of the southern Levant, especially during the last interglacial (LIG), is still under debate. Reliable paleovegetation information for this period, as independent evidence to the paleoenvironment, was still missing. In this study, we present a high-resolution pollen record encompassing 147–89 ka from the Dead Sea deep drilling core 5017-1A. The sediment profile is marked by alternations of laminated marl deposits and thick massive halite, indicating lake-level fluctuations. The pollen record suggests that steppe and desert components predominated in the Dead Sea surroundings during the whole investigated interval. The late penultimate glacial (147.3–130.9 ka) and early last glacial (115.5–89.1 ka) were cool and relatively dry, with sub-humid conditions confined to the mountains that sustained moderate amounts of deciduous oaks. Prior to the LIG optimum, a prevalence of desert components and a concomitant increase in frost-sensitive pistachio trees demonstrate the occurrence of an arid initial warming phase (130.9–124.2 ka). The LIG optimum (124.2 ka–115.5 ka) was initiated by an abrupt grass expansion that was followed by a rapid spread of woodlands in the mountains due to increased moisture availability. The remarkable sclerophyllous expansion points to a strong seasonal moisture deficit. These results contradict previous Dead Sea lake-level investigations that suggested pluvial glacials and a warm, dry LIG in the southern Levant. Prominent discrepancies between vegetation and Dead Sea lake stands are also registered at 128–115 ka, and the potential causes are discussed. In particular, while the pollen spectra mirror increased effective moisture during the LIG optimum, the massive halite deposition is indicative of an extremely low lake level. Given that the climate amelioration triggered the migration of early modern humans to the southern Levant, we speculate that the diverse ecosystems in the region provided great potential for their residence. Across the eastern Mediterranean region, an analogous vegetation succession pattern is observed.

Introduction

Connecting Africa with the Arabian Peninsula, the southern Levant is a hotspot for investigating the dispersal of anatomically modern humans (AMH) to the rest of the world, since their emergence in Africa (Gibbons, 2017). Pivotal findings are the AMH remains in Israel (the Skhul and Qafzeh Caves) dated to the time range of 130–90 thousand years ago (Grün et al., 2005; Mercier et al., 1993; Valladas et al., 1988). These findings suggest the occupation by modern humans in the region during the last interglacial (LIG). The present southern Levant is covered by large areas of uninhabitable desert, whereas, in the past, the present desert barrier was probably a migration corridor with sufficient water and food resources during climate ameliorations (Breeze et al., 2016; Vaks et al., 2007).

The southern Levant is located at the boundary between the Mediterranean and the Saharo-Arabian climate zones. The sensitive response of this region to climatic variations has been documented in the geological archives (Bar-Matthews et al., 2017; Stein, 2014). Nevertheless, inconsistences exist among regional paleoenvironmental archives regarding the glacial-interglacial climate conditions. For instance, a relatively active speleothem deposition occurred in the central and southern Negev Desert during the LIG (Vaks et al., 2007). The evidence points to wetter conditions in the LIG than in the glacial periods. However, inverse climate conditions are indicated, due to the significantly lower Dead Sea lake stands during the LIG as compared to the glacial periods (Waldmann et al., 2010). It is prominent that the lake level at ca. 27–24 ka rose to ca. 270 m higher than the present level, resulting in the mergence of the Dead Sea and the Sea of Galilee (Bartov et al., 2003). Controversies are focused on the relative impact of the climate variables, i.e., precipitation, temperature, evaporation, and seasonality (Gasse et al., 2011; Miebach et al., 2017). In this case, more paleorecords involving independent proxies are needed.

The Dead Sea is a remarkable archive for investigating the paleoenvironment of the southern Levant. So far, studies on a series of proxies, such as sedimental lithology (e.g., Neugebauer et al., 2014), geochemistry (e.g., Torfstein et al., 2009), and pollen assemblages (e.g., Litt et al., 2012), show the great potential of the Dead Sea sediments for documenting changes in regional hydroclimate. Nevertheless, compared to the well-studied last glacial and Holocene sediments, the LIG conditions remain elusive due to the limited availability of materials deposited in the lake margin area. In 2010–2011, the Dead Sea Deep Drilling Project (DSDDP) retrieved sediment cores dated back to ca. 220 ka from the deepest part of the basin (Stein et al., 2011; Torfstein et al., 2015). The project successfully recovered LIG sediments consisting of conspicuously thick halite deposits (Neugebauer et al., 2014). Previous analyses for chronology, lithology, and isotope composition suggested that the LIG period was characterized by low lake levels and generally dry conditions (Torfstein et al., 2015).

Despite this progress, the paleovegetation as independent evidence for the LIG paleoenvironment in the southern Levant is largely unknown. Previous palynological studies in the region are mainly confined to the Holocene (e.g., Langgut et al., 2015; Litt et al., 2012; Neumann et al., 2010) and last glacial period (e.g., MIS 2; Miebach et al., 2017), whereas the LIG pollen records are rare, poorly-dated, and fragmentary (e.g., Weinstein-Evron, 1987). In this study, we present a high-resolution pollen record dated to 147–89 ka, based on the DSDDP sediment core. The main objectives are to reconstruct the paleovegetation in the southern Levant and to elucidate the response of vegetation successions to variations in regional climate. Comparisons with other regional records are made in order to provide new insights into the paleoenvironmental setting of the early modern human dispersal.

Section snippets

The Dead Sea and its setting

The Dead Sea is a hypersaline terminal lake (ca. 27.5% salinity; 76 × 17 km; 760 km2; Fig. 1). It occupies the Dead Sea Basin (DSB) in the Dead Sea Transform, which developed due to the breakup of the African and Arabian plates. This process was accompanied by the formation of narrow valleys and the uplifting of their shoulders at the plate boundary (Garfunkel, 1997). The northern DSB is deep, with a bottom depth of 730 m bmsl (below mean sea level) and a water depth of ca. 300 m. The southern

Drilling campaign and stratigraphy

The coring of the DSDDP was conducted in the northern DSB (Stein et al., 2011). The top depth of the borehole 5017-1A (31°30′28.98″ N, 35°28′15.60″ E) was at 297.46 m below lake level. The total drilled length of this borehole was 455.34 m, retrieving 405.83 m sediments with a recovery rate of 89.13% (for details see Neugebauer et al., 2014). The sediments recover four stratigraphic formations (Fm.). The Amora and Lisan Fm., accumulated during the glacials, mainly consist of marl sediments and

Vegetation and climate

The palynological results are illustrated as a simplified pollen diagram (Fig. 3). Halite samples have very low pollen concentrations (a mean of 1511 grains/cm3) due to a rapid accumulation of salt crystals, while laminated marl samples hold a much higher pollen concentration of 39,910 grains/cm3 on average. Therefore, the fluctuations of pollen concentrations mainly point to the shifts of deposit types. The charcoal concentrations (particles/cm3), conventionally used for representing fire

Conclusions

  • 1)

    This study analyzes pollen, non-pollen-palynomorphs, and charcoal from the deep-drilled Dead Sea 5017-1A sediment core. It reconstructs a detailed vegetation and fire history of the southern Levant at 147–89 ka.

  • 2)

    The late penultimate glacial (MIS 6) and early last glacial (MIS 5d–5b) were cool and were characterized by steppe and desert expansions. Sub-humid conditions were confined to the mountains, where moderate amounts of deciduous oaks were distributed. The initial warming (early MIS 5e) was

Acknowledgements

We thank all our colleagues from the DSDDP scientific party for the drilling, core opening, and sampling campaign. The project is supported by the Collaborative Research Center 806 “Our way to Europe” (DFG-Sonderforschungsbereich). The Ph.D. scholarship for Chunzhu Chen is provided by the China Scholarship Council (CSC). We are grateful for Karen Schmeling for technical support. We acknowledge Andrea Miebach and Nadine Pickarski for the sampling campaign, as well as for constructive discussions

References (110)

  • E.C. Grimm

    CONISS: a Fortran 77 program for stratigraphically constrained cluster-analysis by the method of incremental sum of squares

    Comput. Geosci.

    (1987)
  • R. Grün et al.

    U-series and ESR analyses of bones and teeth relating to the human burials from Skhul

    J. Hum. Evol.

    (2005)
  • A. Haliva-Cohen et al.

    Sources and transport routes of fine detritus material to the Late Quaternary Dead Sea basin

    Quat. Sci. Rev.

    (2012)
  • K.A. Hallin et al.

    Paleoclimate during Neandertal and anatomically modern human occupation at Amud and Qafzeh, Israel: the stable isotope data

    J. Hum. Evol.

    (2012)
  • R.P. Jennings et al.

    The greening of Arabia: multiple opportunities for human occupation of the Arabian Peninsula during the Late Pleistocene inferred from an ensemble of climate model simulations

    Quat. Int.

    (2015)
  • D. Langgut et al.

    Vegetation and climate changes in the South Eastern Mediterranean during the Last Glacial-Interglacial cycle (86 ka): new marine pollen record

    Quat. Sci. Rev.

    (2011)
  • V. Lebreton et al.

    A neotaphonomic experiment in pollen oxidation and its implications for archaeopalynology

    Rev. Palaeobot. Palynol.

    (2010)
  • T. Litt et al.

    Holocene climate variability in the Levant from the Dead Sea pollen record

    Quat. Sci. Rev.

    (2012)
  • L. López-Merino et al.

    Using palynology to re-assess the Dead Sea laminated sediments - indeed varves?

    Quat. Sci. Rev.

    (2016)
  • G.M. MacDonald et al.

    The reconstruction of boreal forest fire history from lake sediments: a comparison of charcoal, pollen, sedimentological, and geochemical indices

    Quat. Sci. Rev.

    (1991)
  • D. Magri et al.

    Orbital signatures and long-term vegetation patterns in the Mediterranean

    Quat. Int.

    (2000)
  • N. Mercier et al.

    Thermoluminescence date for the Mousterian burial site of Es-Skhul, Mt. Carmel

    J. Archaeol. Sci.

    (1993)
  • A. Miebach et al.

    Vegetation and climate during the Last Glacial high stand (ca. 28-22 ka BP) of the Sea of Galilee, northern Israel

    Quat. Sci. Rev.

    (2017)
  • A.R. Millard

    A critique of the chronometric evidence for hominid fossils: I. Africa and the Near East 500–50 ka

    J. Hum. Evol.

    (2008)
  • A.M. Milner et al.

    Vegetation responses to abrupt climatic changes during the last interglacial complex (marine isotope stage 5) at Tenaghi Philippon, NE Greece

    Quat. Sci. Rev.

    (2016)
  • D. Neev et al.

    Geophysical investigations in the Dead Sea

    Sediment. Geol.

    (1979)
  • I. Neugebauer et al.

    Lithology of the long sediment record recovered by the ICDP Dead Sea deep drilling project (DSDDP)

    Quat. Sci. Rev.

    (2014)
  • F. Neumann et al.

    Vegetation history and climate fluctuations on a transect along the Dead Sea west shore and their impact on past societies over the last 3500 years

    J. Arid Environ.

    (2010)
  • N. Pickarski et al.

    Vegetation and environmental changes during the last interglacial in eastern Anatolia (Turkey): a new high-resolution pollen record from Lake Van. Palaeogeography, Palaeoclimatology

    Palaeoecology

    (2015)
  • E.M. Scerri et al.

    Earliest evidence for the structure of Homo sapiens populations in Africa

    Quat. Sci. Rev.

    (2014)
  • G. Schiller et al.

    Water use by Tabor and Kermes oaks growing in their respective habitats in the Lower Galilee region of Israel

    For. Ecol. Manag.

    (2010)
  • G. Schiller et al.

    Estimating the water use of a sclerophyllous species under an East-Mediterranean climate: I. Response of transpiration of Phillyrea latifolia L. to site factors

    For. Ecol. Manag.

    (2002)
  • M. Stockhecke et al.

    Millennial to orbital-scale variations of drought intensity in the Eastern Mediterranean

    Quat. Sci. Rev.

    (2016)
  • A.M. Swain

    A history of fire and vegetation in northeastern Minnesota as recorded in lake sediments

    Quaternary Research

    (1973)
  • A. Torfstein et al.

    Dead Sea drawdown and monsoonal impacts in the levant during the last interglacial

    Earth Planet Sci. Lett.

    (2015)
  • A. Torfstein et al.

    U-series and oxygen isotope chronology of the mid-Pleistocene Lake Amora (Dead Sea basin)

    Geochem. Cosmochim. Acta

    (2009)
  • P.C. Tzedakis

    Seven ambiguities in the Mediterranean palaeoenvironmental narrative

    Quat. Sci. Rev.

    (2007)
  • A. Vaks et al.

    Paleoclimate reconstruction based on the timing of speleothem growth and oxygen and carbon isotope composition in a cave located in the rain shadow in Israel

    Quat. Res.

    (2003)
  • A. Vaks et al.

    Middle-late quaternary paleoclimate of northern margins of the Saharan-Arabian desert: reconstruction from speleothems of Negev desert, Israel

    Quat. Sci. Rev.

    (2010)
  • J.R. Allen et al.

    Rapid environmental changes in southern Europe during the last glacial period

    Nature

    (1999)
  • P. Alpert et al.

    Recent changes in the climate of the Dead Sea valley

    Climatic Change

    (1997)
  • S.J. Armitage et al.

    The southern route "out of Africa": evidence for an early expansion of modern humans into Arabia

    Science

    (2011)
  • M. Bar-Matthews et al.

    Climate and environment reconstructions based on speleothems from the Levant

  • S. Barker et al.

    800,000 years of abrupt climate variability

    science

    (2011)
  • Y. Bartov et al.

    Catastrophic arid episodes in the eastern mediterranean linked with the north atlantic heinrich events

    Geology

    (2003)
  • H.-J. Beug

    Pollenbestimmung für Mitteleuropa und angrenzende Gebiete

    (2004)
  • A. Brauer et al.

    Evidence for last interglacial chronology and environmental change from Southern Europe

    Proc. Natl. Acad. Sci.

    (2007)
  • R. Cheddadi et al.

    Eastern mediterranean quaternary paleoclimates from pollen and isotope records of marine cores in the nile Cone area

    Paleoceanography

    (1995)
  • A. Danin

    Flora and vegetation of Israel and adjacent areas

    Zoogeography Israel

    (1992)
  • A. Danin et al.

    Revision of the plant geographical territories of Israel and Sinai

    Plant Systemat. Evol.

    (1987)
  • Cited by (26)

    View all citing articles on Scopus
    View full text