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| Titel |
Factors controlling the geochemical composition of Limnopolar Lake sediments (Byers Peninsula, Livingston Island, South Shetland Island, Antarctica) during the last ca. 1600 years |
| VerfasserIn |
Antonio Martínez Cortizas, I. Rozas Muñiz, T. Taboada, M. Toro, I. Granados, S. Giralt, S. Pla-Rabes |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 5, no. 2 ; Nr. 5, no. 2 (2014-07-10), S.651-663 |
| Datensatznummer |
250115315
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| Publikation (Nr.) |
 copernicus.org/se-5-651-2014.pdf |
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| Zusammenfassung |
| We sampled a short (57 cm) sediment core in Limnopolar Lake (Byers
Peninsula, Livingston Island, South Shetland Islands), which spans the last
ca. 1600 years. The core was sectioned at high resolution and analyzed
for elemental and mineralogical composition, and scanning electron microscope and energy dispersive X-ray spectrometer (SEM-EDS) analysis of glass
mineral particles in selected samples. The chemical record was characterized
by a contrasted pattern of layers with high Ca, Ti, Zr, and Sr concentrations
and layers with higher concentrations of K and Rb. The former were also enriched in
plagioclase and, occasionally, in zeolites, while the latter were relatively
enriched in 2 : 1 phyllosilicates and quartz. This was interpreted as
reflecting the abundance of volcaniclastic material (Ca rich) versus
Jurassic–Lower Cretaceous marine sediments (K rich) – the dominant
geological material in the lake catchment. SEM-EDS analysis revealed the
presence of abundant volcanic shards in the Ca-rich layers, pointing to
tephras most probably related to the activity of Deception Island volcano
(located 30 km to the SE). The ages of four main peaks of volcanic-rich
material (AD ca. 1840–1860 for L1, AD ca. 1570–1650 for L2,
AD ca. 1450–1470 for L3, and AD ca. 1300 for L4) matched
reasonably well the age of tephra layers (AP1 to AP3) previously identified
in lakes of Byers Peninsula. Some of the analyzed metals (Fe, Mn, Cu, and Cr)
showed enrichments in the most recent tephra layer (L1), suggesting relative
changes in the composition of the tephras as found in previous
investigations. No evidence of significant human impact on the cycles of most
trace metals (Cu, Zn, Pb) was found, probably due to the remote location of
Livingston Island and the modest research infrastructures; local
contamination was found by other researchers in soils, waters and marine
sediments on areas with large, permanent research stations. Chromium is the
only metal showing a steady enrichment in the last 200 years, but this cannot
be directly attributed to anthropogenic pollution since recent research
supports the interpretation that climatic variability (reduced moisture
content and increased wind intensity) may have resulted in enhanced fluxes of
mineral dust and trace elements (Cr among them) to Antarctica. At the same
time, some features of the chemical record suggest that climate may have also
played a role in the cycling of the elements, but further research is needed
to identify the underlying mechanisms. |
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