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| Titel |
The early Holocene humid period in the Tayma palaeolake, NW Arabian Peninsula -- A high-resolution micro-facies and geochemical approach |
| VerfasserIn |
Ina Neugebauer, Birgit Plessen, Michèle Dinies, Max Engel, Rik Tjallingii, Achim Brauer |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250124893
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| Publikation (Nr.) |
 EGU/EGU2016-4396.pdf |
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| Zusammenfassung |
| The Tayma palaeolake is a rare archive of the early Holocene humid period in northern
Arabia (Dinies et al. 2015; Engel et al. 2012). Here we present a ca. 1 m thick and 500 years
spanning annually laminated sediment section that was deposited in the centre of the former
lake from ca. 8500 to 8000 calibrated years (cal. yrs) BP, as determined by AMS 14C dating
of pollen concentrates (Dinies et al. 2015). High-resolution micro-facies analyses based on
thin section microscopy, μXRF element scanning, δ18Ocarb and δ13Ccarb measurements on
single carbonate laminae, as well as geochemical measurements on bulk samples for TOC,
CaCO3, C/N ratio, δ18Ocarb, δ13Ccarb, δ13Corg and δ15N determination were performed in
order to investigate the sedimentological and geochemical changes along the varved
sequence in great detail. The finely laminated marl sediments are mainly composed
of sub-mm thick laminae of endogenic aragonite, organic matter and diatoms, as
well as occasional, often graded silt-clay layers. Following an early lake phase
from ca. 8700 to 8500 cal. yrs BP characterized by coarsely laminated, presumably
non-annual marl sediments that are rich in ostracods, three main varved phases
can be distinguished within the investigated section: (1) aragonitic-organic varves
from ca. 8500 to 8300 cal. yrs BP, (2) diatom-organic varves from ca. 8300 to 8100
cal. yrs BP that frequently include aragonite laminae and occasionally gastropod
and ostracod shells, and (3) organic varves from ca. 8100 to 8000 cal. yrs BP with
decreasing diatom and aragonite laminae and an increasing frequency of gypsum
layers. After this period, gypsum becomes abundant and fine lamination appears only
sporadically. In addition, we observe increasing trends of TOC, C/N and δ13Ccarb and
decreasing δ18Ocarb during phase 1 and excess δ18Ocarb, δ13Ccarb and TOC values
during phase 2, pointing towards the maximum lake productivity and increased
seasonal precipitation. We interpret this sedimentological-geochemical succession as
reflecting a high moisture availability during the early Holocene that culminates at
around 8200 cal. yrs BP (phase 2). Stimulated by the coincidence in timing, we will
discuss possible relations to the so-called 8.2 ka cold event in the North Atlantic
realm.
This study is a contribution to the research project "CLEAR - Holocene CLimatic Events
of Northern ARabia" (https://clear2018.wordpress.com/).
References:
Dinies, M., Plessen, B., Neef, R., and Kürschner, H.: When the desert was green:
Grassland expansion during the early Holocene in northwestern Arabia, Quaternary
International, 382, 293-302, 2015.
Engel, M., Brückner, H., Pint, A., Wellbrock, K., Ginau, A., Voss, P., Grottker, M.,
Klasen, N., and Frenzel, P.: The early Holocene humid period in NW Saudi Arabia –
Sediments, microfossils and palaeo-hydrological modelling, Quaternary International, 266,
131-141, 2012. |
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