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| Titel |
GEMAS: Mineral magnetic properties of European agricultural soils |
| VerfasserIn |
Dilyara Kuzina, Lina Kosareva, Leysan Fattakhova, Karl Fabian, Danis Nourgaliev, Clemens Reimann |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250110730
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| Publikation (Nr.) |
 EGU/EGU2015-10756.pdf |
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| Zusammenfassung |
| The GEMAS survey of European agricultural soil provides a unique opportunity to create the
first comprehensive overview of mineral magnetic properties in agricultural soil on a
continental scale. Samples from the upper 20Âcm were taken in large agricultural
fields (Ap-sample) at a density of 1 site/2500 km2. After air drying and sieving to
< 2Âmm, low (460ÂHz), and high frequency (4600ÂHz) magnetic susceptibility k was
measured on 2500 samples using a Bartington MS2B sensor to obtain frequency
dependence of magnetic susceptibility kfd. Hysteresis properties are determined using a J
coercivity spectrometer, built in the paleomagnetic laboratory of Kazan University,
providing for each sample a modified hysteresis loop, backfield curve, acquisition
curve of isothermal remanent magnetization, and a viscous IRM decay spectrum.
Each measurement set is obtained in a single run from zero field up to 1.5ÂT and
back to -1.5ÂT, taking approximately 15 minutes. This allows to measure a wide
range of magnetic parameters for large sample collections. Because the GEMAS
geochemical atlas provides a comprehensive set of geochemical measurements
characterizing the individual soil samples, the new data allow to study magnetic
parameters in relation to chemical and geological parameters. The results show a
clear large scale spatial distribution with e.g. broad distinct lows of k over sandy
sediments of the last glaciation in central northern Europe and other sedimentary basins.
More localized positive k anomalies occur near young volcanism, or old basalts
exposed on the surface. On the other hand, frequency dependence of k displays a
much more scattered behavior, indicating either high noise level, or large local
variability. Clearly distinguishable, small-scale patterns in the randomized data set
indicate that the latter is more likely. This indicates that local influences on soil
magnetic properties, including anthropogenic effects, may be easier detected by
frequency dependence than by k itself, which is largely controlled by geological and
climatic background variability. Mapping the isothermal mineral magnetic properties
shows again a clear relation to large scale European geology. Thereby, the GEMAS
data set of magnetic parameters provides a continent wide reference of the natural
background in Ap soil. For the first time the geological background variability of
magnetic minerals for national and local soil studies is defined at the European scale. |
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