The rare Earth element distribution over Sweden: geogenic and anthrophogenic sources – local or regional case study
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Disciplines:
Bedrock geology, geochemistry and environmental geology.
Aim:
- identify the main changes in REE distribution related to geology and weatherin
- discriminate between the natural geogenic REE content and anomalies at a regional scale due to anthropogenic source
- collect basic information about REE in Sweden
- provide evidence of anthropogenic source of REE in Sweden
- provide evidence of geogenic source of REE in Sweden
- in the local case study , provide the genesis and forming of REE related to geological processes.
Background:
The evaluation and interpretation of geochemical data relies on understanding the nature of the material that has been sampled. Different materials require a variety of methods and techniques for the interpretation of results. In the case of surficial sedimentary materials (glacial till and stream sediments), different size In 1994 the Forum of European Geological Surveys (FOREGS) initiated a programme to collect a standardized and controlled geochemical database for Europe, with the aim of compiling the first geochemical atlas of Europe (Plant et al.1997). As a result, a large database of geochemical data, covering 26 European countries and containing chemical analyses of more than 70 elements from different environmental media (soils, stream and floodplain sediments and waters), is now available (Salminen et al. 2005), together with a data description (De Vos et al. 2006). The EuroGeosurveys geochemical mapping of agricultural and grazing land soils project (GEMAS) initiating a new programme to collect samples of agricultural soil and from land under permanent grass cover over Europe The GEMAS project will deliver good quality and comparable exposure data of metals in soil; soil properties know to influence the bioavailability and toxity of metals will also be determined in soil at the European scale (GEMAS report- 2009).
REE normally occur naturally at trace levels in the upper continental crust and REE pattern normalized to chondritic abundance (Nakamura, 1974), are used to investigate igneous, sedimentary and metamorphic process. REE are increasingly used in a number of technological applications, including new high- technology materials, electronic components and semiconductors. REE oxides are also of particular interest for developing material for high- temp. applications, because of their exceptionally high thermal stability (Adochi et al., 2004). The increasing use of REE in industrial process suggests that REE release into the environment is likely to increase in the future with potential impacts on human health (Fedel et al., 2008).
As point of geological aspect, Sweden is one of the known countries for its REE-mineralization. The Element Ce and La were discovered in Bastnäs, which produced 4,500 tons of Ce ore during 1875-1888. According to mineral information office in Geological Survey, still the Bastnäs area is considered as the most interesting area for REE in Sweden. Bastnäs type deposit is stratabound FeO-Cu-REE ore deposit within the iron ores and skarn environment and closely associated with copper-bismuth mineralization. The other type of REE mineralization is associated with apatite-iron ore , i.e, Kiruna type which contain significant amount of LREE. The ores are related mainly to magmatitc-hydrothermal character and Monazite or allanite often occurs in the apatite up to 0.8% REE, (SGU report).
The Alnö Alkaline carbonatite complex in central Sweden is known for high grades of Yttrium, Ba , Se, and Lanthanium. Airborne magnetic survey has identified ca. 300 circular anomalies that are potential diatremes in the vincinity. And finally, REE-U anomalous phosphorite occur as paleozoic schists in the Caledonian region. The mineralisations are associated with concretions of carbonate-fluorapatite, which constitutes 20% of the rock.
Content and methods:
Geochemistry data, lithogeochemistry, GIS.
Scope:
To be discussed.
Contact:
Martiya Sadeghi
Tel: 018-17 92 32
E-mail: martiya.sadeghi@sgu.se
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