Project CLEAR Workshop, GFZ Potsdam, 26 Jan 2018

On January 26 2018, the CLEAR project members got together for a joint workshop at the German Research Centre for Geosciences GFZ in Potsdam. For this meeting we aimed to exchange new results, to discuss the age-depth model of the sediment profiles, and to develop a publication plan for the last project phase.

Michelé Denies introduced to us the latest version of the age-depth model, applying for all five parallel sediment cores of the Tayma palaeolake. After several years of work and many, many, many C-14 dates we achieved a final stage of the model, which we all agreed on. All proxy data obtained from the different sediment cores can now be directly compared. This important step forms the basis for all the planned research papers.

One of these papers will comprehensively investigate the link of the humid phase in the Tayma region to changes in atmospheric circulation and the role of possible hemispheric teleconnections. Ina Neugebauer presented for this purpose the publication outline. We planned to integrate most of the available proxy data in this paper (i.e. sediments, mineralogy, isotopes, microfossils, vegetation, biomarkers), in order to create a big picture of the lake system development in the past and to analyse the changes from various angles.

This workshop reinforced once again the cooperation between the CLEAR project members and boosted the motivation of all people in the last project phase.

Workshop Januar 2018.jpg

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S1 cryptotephra found in deposits of the Tayma palaeolake – paper published!

While tirelessly analysing and counting warve couples and organic-rich sections of the palaeolake sequence of Tayma, Ina Neugebauer and colleagues identified tiny glass shards under the light microscope.  The major element composition of the glasses was measured using an araldite-embedded sample and an electron microprobe in order to compare the mineralogical fingerprint with known tephras in the wider Eastern Mediterranean-Levantine region. It turned out to be identical to the so-called S1 tephra layer found at Yammoûneh (Lebanon), Sodmein Cave (Egypt), the Dead Sea, and the southeastern Levantine basin, and is associated with an early Holocene eruption of the Erciyes Dag volcano in central Anatolia. By applying the high-resolution pollen based age model of Dinies et al. (2015), the age of the tephra can be determined as 9041+/-254 cal yrs BP. Parallel findings from the Dead Sea, published in the same paper, narrow its age down to 8939+/-83 cal yrs BP and, furthermore, provide an early Holocene marine reservoir age for the southeastern Levantine basin of 320+/-50 years.

S1-Tephra_Photos-1
Backscattered electron and light microscope images of volcanic glass shards of S1 tephra identified in sediment cores from the Dead Sea (Neugebauer et al., 2017).

Citation:

Neugebauer, I., Wulf, S., Schwab, M.J., Serb, J., Plessen, B., Appelt, O., Brauer, A., 2017. Implications of S1 tephra findings in Dead Sea and Tayma palaeolake sediments for marine reservoir age estimation and palaeoclimate synchronisation. Quaternary Science Reviews 170, 269-275.

Ostracoda and foraminifera of the Tayma palaeolake – Paper published!

The Holocene palaeo-lake at Tayma hosts a unique association of athalassic marine microfauna. The formaniferal taxa identified in the deposits of the former inland lake are usually found in marginal marine environments, but have been introduced by migratory birds, adapted well to the saline continental waters and started to thrive due to a low level of competition. In a paper published in the current issue of the Journal of Foraminiferal Research, Anna Pint and colleagues present details on the species occurrence and test anomalies in foraminifera as well as the distribution of sieve pore shapes in the carapaces of ostracoda. Based on a comparison with comparable assemblages in marginal marine environments, it is suggested that that a combination of low diversity, exclusively marginal marine taxa, combined with occurrences of test anomalies >10% can be used to recognize athalassic saline waters in the fossil record.

Citation:

Pint, A., Engel, M., Melzer, S., Frenzel, P., Plessen, B., Brückner, H., 2017. How to discriminate athalassic and marginal marine microfaunas? Foraminifera and other fossils from an early Holocene continental lake in northern Saudi Arabia. Journal of Foraminiferal Research 47, 175-187.

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Foraminifera from Tayma, white scale: 0.1mm. 1: Ammonia tepida, normal test, spiral view. 2: A. tepida, chamber deformation, spiral view. 3: A. tepida, multiple test. 4: Quinqueloculina seminula, normal test. 5: Q. seminula, changes of growth direction. 6: Q. seminula, multiple test. 7: Flintinoides labiosa, normal test. 8: F. labiosa, changes of growth direction. 9: Discorinopsis aguayoi, normal test, spiral view. 10: D. aguayoi, normal test, umbilical view.

EGU General Assembly 2017

This year, two papers covering recent progress in Project CLEAR were presented at the EGU General Assembly 2017, Vienna, Austria (23-28 April 2017).

In her talk on Friday, Nadine Dräger provided first insights into her dataset on lipid biomarkers from the palaeo-lake sequence of the Tayma sabkha basin. The presentation, held in a session comprising (palaeo-)environmental studies from early hominin Anthropocene sites, showed how the peak in concentration of long-chain n-alkanes positively correlates with what is assumed to represent the highest lake levels and most humid period in the Holocene. This peak is a further corroboration of an increase of mostly grassland vegetation at that time, as already identified in the local pollen record. Interestingly, the onset of most likely human faecal biomarkers significantly predates the initial occurrence of cultivation-related in the pollen spectra, possibly indicating nomad-like frequentation before the phase of mor eintense occupation and agricultural activities in the oasis since c. 6300 years ago. Please download the Abstract here.

Ina Neugebauer presented her findings on cryptotephra in the Holocene palaeolake sequence of Tayma, which has the same geochemical characteristics as the  distal “S1 tephra” identified in  the Yammoûneh palaeolake, Lebanon, the SE Levantine basin, and Sodmein Cave in The Estern Desert of Egypt. The pollen-based age model of the sequence provides a timing of 9041+/-254 cal yr BP and correlates well with previous age estimates of the Early Holocene eruption of Erciyes Dag volcano in central Anatolia, Turkey, which led to the formation of sapropel S1 in the Mediterranean Basin. Please download the Abstract here.

 

Project CLEAR Workshop, GFZ Potsdam, 22 Feb 2017

An interim workshop of Project CLEAR members was held at GFZ Potsdam on 22 Feb 2017 in order to

  • update each other on the progress of multi-proxy analyses of the palaeo-lake deposits at the participating institutions;
  • distribute sediment samples and stratigraphical profiles taken during fieldwork in Dec 2015, which had finally arrived in Jan 2017(!)

Progress reports were provided on lithological/geochemical analysis, diatom analysis, and foraminifer/ostracod analysis of the mastercore from the central sabkha basin. For the first time, we synoptically observed distinct trends in, e.g. salinity or evaporation, across proxies based on high-resolution data from Tayma, so everybody got kinda excited… Analyses are ongoing, but first data-ladden papers have already been submitted.

Distribution of profile samples from trench Tay 300 (left) - and how they were taken in the field (right)
Distribution of profile samples from trench Tay 300 (left) – and how they were taken in the field (right)

Annual Meeting on “Desert Margin Research”, Rauischholzhausen, 03-04 Feb 2017

The Annual Meeting of the working group “Desert Margin Research” of the Deutsche Gesellschaft für Geographie (DGfG) was held in the castle of Rauischholzhausen near Gießen on 03-04 Feb 2017. Project CLEAR was present with a poster gathering the most striking palaeobiological evidence for a the early Holocene lake as well as preliminary results of the shoreline survey.

The meeting provided the opportunity for several exiled Syrian geoscientists to report on the current situation of academic life threatened by the ongiong civil war, thereby dwarfing all the aspects of European academia that we consider as problems or deficiencies in our daily work.

Regarding the identification of shorelines of the contracting palaeolake at Tayma during the mid- to late Holocene aridisation, Peter Felix-Henningsen of the University of Gießen gave a fascinating talk about how he uses swamp ores and calcretes formed in shoreline positions in order to reconstruct a shirinking lake in space and time in Niger. In densely vergetated, flat lake-shore areas, vertical rhizoconcretions form through the accumulation of goethite. These swamp ores preserve the underlying sands and can be reliably dated by 14C. Unfortunately, these features have not yet been found at Tayma…

Poster presentation at the Annual meeting "Desert Margin Research"
Poster presentation at the Annual meeting “Desert Margin Research”

Wetlands or Lakes Pt. II – Discussion Papers published!

Based on some doubts on the reinterpretation of sedimentary palaeo-lake records on the Arabian Peninsula in a paper by Enzel et al. (2015), which were already raised in an earlier blogpost, a Discussion Paper was published this month led by Project CLEAR PI Max (Engel et al., 2017). In their initial contribution, Enzel et al. (2015) conclude that sites, reconstructed as perennial lakes during the Early Holocene Humid Period (EHHP) in earlier studies, rather represent palaeo-wetland environments and that the majority of the Arabian Peninsula experienced no or, if at all, only a very minor increase of rainfall at that time. The new Discussion Paper, however, backed by field geomorphologists, Quaternary geologists and (geo-)archaeologists from the Universities of Bern, Oxford Brookes, Oxford and Freiburg as well as the MPI for the Science of Human History Jena, identifies key sedimentolgical and palaeobiological indicators for lake environments (e.g. foraminifers, barnacles etc.), some of which are not referred to in the initial study. In their reply, Enzel et al. (2017) acknowledge the robust evidence brought up for perennial water bodies, whereas disagreement still exists regarding their definition: Were they shallow and spatially limited to be defined as wetlands or let their size, ecology and chemistry categorize them as lakes? Enzel et al. (2017) emphasize the presence of geomorphic remnants of shorelines as a mandatory feature of palaeo-lakes, a view challenged in the comment (Engel et al., 2017). Anyway, at Tayma, a systematic mapping campaign was carried out during fieldwork in December 2015. The debate is ongoing and genuinely appreciated by both sides!

Fig. 1 in Engel et al. 2017: Overview of key Holocene palaeo-lake sites on the Arabian Peninsula.
Fig. 1 in Engel et al. (2017): Overview of some key Holocene palaeo-lake sites on the Arabian Peninsula.

References

Engel, M., Matter, A., Parker, A.G., Parton, A., Petraglia, M.D., Preston, G., Preusser, F., 2017. Lakes or wetlands? A comment on ‘The middle Holocene climatic records from Arabia: Reassessing lacustrine environments, shift of ITCZ in Arabian Sea, and impacts of the southwest Indian and African monsoons’ by Enzel et al. Global and Planetary Change 148, 258-267.

Enzel, Y., Quade, J., Kushnir, Y., 2015. The middle Holocene climatic records from Arabia: Reassessing lacustrine environments, shift of ITCZ in Arabian Sea, and impacts of the southwest Indian and African monsoons. Global and Planetary Change 129, 69-91.

Enzel, Y., Quade, J., Kushnir, Y., 2017. Response to Engel et al. (in press): Lakes or wetlands? A comment on “The middle Holocene climatic records from Arabia: Reassessing lacustrine environments, shift of ITCZ in Arabian Sea, and impacts of the southwest Indian and African monsoons” by Enzel et al. (2015). Global and Planetary Change 148, 268-271.