Lacustrine laminated sediments are often varves representing annual rhythmic deposition. The Dead Sea high-stand laminated sections consist of mm-scale alternating detrital and authigenic aragonite laminae. Previous studies assumed these laminae were varves deposited seasonally. However, this assumption has never been robustly validated. Here we report an examination of the seasonal deposition of detrital-aragonite couplets from two well-known Late Holocene laminated sections at the Ze'elim fan-delta using palynology and grain-size distribution analyses. These analyses are complemented by the study of contemporary flash-flood samples and multivariate statistical analysis. Because transport affects the pollen preservation state, well-preserved (mostly) air-borne transported pollen was analysed separately from badly-preserved pollen and fungal spores, which are more indicative of water transport and reworking from soils. Our results indicate that (i) both detrital and aragonite laminae were deposited during the rainy season; (ii) aragonite laminae have significantly lower reworked and fungal spore concentrations than detrital and flash-flood samples; and (iii) detrital laminae are composed of recycling of local and distal sources, with coarser particles that were initially deposited in the Dead Sea watershed and later transported via run-off to the lake. This is in line with previous carbon balance studies that showed that aragonite precipitation occurs after the massive input of TCO2 associated with run-off episodes. Consequently, at least for the Holocene Ze'elim Formation, laminated sediments cannot be considered as varves. Older Quaternary laminated sequences should be re-evaluated.
Bibliographical noteFunding Information:
This research was made possible through the support of the British Council's Britain-Israel Research and Academic Exchange Partnership (BIRAX) , which aims to further institutional links between universities in the UK and Israel, awarded to S.A.G. Leroy and R. Bookman and entitled “Resolving the deposition pattern of the Dead Sea laminae and its implication for understanding hydro-climatic short-term variations in the Levant“ (BY2/GEO/08), and partly by an Israel Science Fund grant (ISF, Grant # 1093/10 ) to R. Bookman. L. López-Merino was first supported by a post-doctoral fellowship (Spanish Government) at Brunel University London and later by the Brunel MINT Scheme. We thank the valuable help of Amanda Rozeik (Brunel University London) with the palynological extraction, and Uri Sha'anan and Dr Nimer Taha (University of Haifa) with the grain-size analysis and the sampling of flash-floods. We are indebted to Professor Antonio Martínez Cortizas (University of Santiago de Compostela) and Dr Stephen Kershaw (Brunel University London) for their perceptive comments on earlier drafts.
© 2016 The Authors.
- Air-borne pollen
- Dead Sea
- Flash-flood events
- Laminated sediments
- Reworked pollen
ASJC Scopus subject areas
- Global and Planetary Change
- Ecology, Evolution, Behavior and Systematics