Beryllium isotopes as tracers of Lake Lisan (Last Glacial Dead Sea) hydrology and the Laschamp geomagnetic excursion

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dc.contributor.authorBelmaker, Ren_AU
dc.contributor.authorStein, Men_AU
dc.contributor.authorBeer, Jen_AU
dc.contributor.authorChristl, Men_AU
dc.contributor.authorFink, Den_AU
dc.contributor.authorLazar, Ben_AU
dc.date.accessioned2014-10-27T05:33:18Zen_AU
dc.date.available2014-10-27T05:33:18Zen_AU
dc.date.issued2014-08-15en_AU
dc.date.statistics2014-10-27en_AU
dc.description.abstractThe content of the cosmogenic isotope Be-10 (t(1/2) = 1.39 Ma) in lacustrine sediments that deposit in lakes with a large watershed is susceptible to both climate and cosmogenic production rate variations. In order to distinguish between these two controls, we measured Be-10 and major elements in several sections of the annually laminated sediments of the Lake Lisan (the last Glacial precursor of the Dead Sea) that are composed of detrital sediments and primary (evaporitic) aragonites. The sections were selected to represent regional hydrology and climate as reflected by different lake configurations (level rise, drop and high-stands) and rapid change in the Be-10 production rate during the Laschamp geomagnetic excursion. Since the short-lived cosmogenic "sister" of Be-10, Be-7 (t(1/2) = 53.3 d) has virtually no recycled component, the recycled Be-10 in Lake Lisan detrital sediments was evaluated by measuring Be-7 in their modern equivalents: modern flood suspended matter, dust and mud cracks. Our results demonstrate that although the recycled Be-10 component is significant, secular variations in the Be-10 concentration in Lake Lisan sediments correlate with hydrological variations and geomagnetic excursions. During periods of moderate variations in Be-10 production rate, the Be-10 concentration in the Lisan detrital sediments positively correlates with lake level, Al + Fe content and the (Al + Fe)/(Ca + Mg) ratio. These correlations suggest that the Be-10 is adsorbed on the fine silicate component (probably clays) of the detrital laminae. The fine silicates together with carbonates were transported to Dead Sea drainage basin mainly as airborne dust that after a short residence time was washed into Lake Lisan as flood suspended matter. We suggest that preferential dissolution of carbonates in the flood suspended matter concentrated the residual fine component leading to the positive correlation between Be-10 and the (Al + Fe)/(Ca + Mg) ratio. During periods of increased water discharge more carbonates were dissolved and hence the Be-10 concentration in the detrital laminae increased. During periods of rapid increase in the Be-10 production rate (e.g. the Laschamp excursion), Be-10 showed a similar to 2 fold increase, beyond the above-mentioned correlations (lake levels and Al + Fe contents). This observation suggests that Lake Lisan can serve as a potential high-resolution archive of Be-10 production rate variations during periods of geomagnetic excursions. © 2014, Elsevier Ltd.en_AU
dc.identifier.citationBelmaker, R., Stein, M., Beer, J., Christl, M., Fink, D., & Lazar, B. (2014). Beryllium isotopes as tracers of Lake Lisan (Last Glacial Dead Sea) hydrology and the Laschamp geomagnetic excursion. Earth and Planetary Science Letters, 400, 233-242. doi:10.1016/j.epsl.2014.05.049en_AU
dc.identifier.govdoc5787en_AU
dc.identifier.issn0012-821Xen_AU
dc.identifier.journaltitleEarth and Planetary Science Lettersen_AU
dc.identifier.pagination233-242en_AU
dc.identifier.urihttp://dx.doi.org/10.1016/j.epsl.2014.05.049en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/5958en_AU
dc.identifier.volume400en_AU
dc.language.isoenen_AU
dc.publisherElsevier Science BVen_AU
dc.subjectBerylliumen_AU
dc.subjectIsotopesen_AU
dc.subjectLakesen_AU
dc.subjectDead Seaen_AU
dc.subjectSolar activityen_AU
dc.subjectEvolutionen_AU
dc.titleBeryllium isotopes as tracers of Lake Lisan (Last Glacial Dead Sea) hydrology and the Laschamp geomagnetic excursionen_AU
dc.typeJournal Articleen_AU
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