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| Titel |
Mobility of major and trace elements in andosols from Iceland: correlating extent of chemical weathering with climatic conditions at soil formation sites |
| VerfasserIn |
Birgir V. Oskarsson, Morten S. Riishuus, Ólafur Arnalds |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250044066
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| Zusammenfassung |
| Element mobility within volcanic soil profiles developed in diverse climatic conditions in
Iceland is assessed. Soils were selected from areas with good monitoring of annual
temperature and precipitation and the degree of weathering and elemental behavior was
compared. Most soils in Iceland develop in parent materials of volcanic origin, including a
variety of basaltic and andesitic tephras, hyaloclastites and glacial tillites. Most Icelandic
soils are subject to considerable flux of eolian deposition and in times receive tephra ejecta
from volcanic eruptions. In this study, samples were carefully extracted from brown
and gleyic andosol horizons for major and trace element analysis. Each horizon
is representative of a pedogenetic stage. Preliminary results show that the major
elements TiO2, Al2O3 and Fe2O3 (T) (mean wt% = 3.4, 19.2, 17.3) appear immobile
relative to the parent material (p.m. mean wt% = 1.6, 14.6, 10.9) and are found
enriched within more mature horizons. The base cations MgO, CaO and Na2O
(mean wt% = 4.11, 7.23, 1.8) are depleted in these horizons (p.m. mean wt% = 9.1,
11.8, 2.0) showing mobilization during pedogenesis. The trace elements reveal no
strong enrichment/depletion trend with a range of mobility from mobile to immobile
Rb, Zn, Y, Sr, Ba, Ni, La, Cr, Cu, Nd, V, Zr and Nb. Soils developed in colder and
dryer climatic conditions in Iceland (MAT = -1-C and MAP = 1000mm) show higher levels of
weathering (CIA-K = 50-65) and element mobilization. The parent materials have a
CIA-K weathering index of 37. The relationship of the covariance of the climate
parameters with extent of chemical weathering may be quantified as climofunctions to
deliver proxy climate data under cool to subarctic conditions. Our results may yield
reasonable tools for determining past climate variations from weathered tephras found
as paleosols in the Neogene lava piles of Iceland and other volcanic provinces. |
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