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

QUATERNARY SCIENCE REVIEWS

卷:140

Article

Lopez-Merino, Lourdes¹  Leroy, Suzanne A. G.¹  Eshel, Amram²  Epshtein, Valentina²  Belmaker, Reuven³  Bookman, Revital³ 

[1] Brunel Univ London, Inst Environm Hlth & Soc, Uxbridge UB8 3PH, Middx, England

[2] Tel Aviv Univ, Ted Arisson Airborne Allergens Monitoring Lab, IL-69978 Tel Aviv, Israel

[3] Univ Haifa, Charney Sch Marine Sci, Dr Strauss Dept Marine Geosci, IL-31905 Haifa, Israel

关键词: Dead Sea;    Laminated sediments;    Aragonite;    Air-borne pollen;    Reworked pollen;    Flash-flood events;   

DOI  :  10.1016/j.quascirev.2016.03.024

来源: Elsevier

【 摘 要 】

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. (C) 2016 The Authors. Published by Elsevier Ltd.

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