bedrock u-th-k signatures in the ongoing european …bedrock u-th-k signatures in the ongoing...
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Bedrock U-Th-K signatures in
the ongoing European Atlas of
Natural Radiation Roberto Braga
BiGeA, Università di Bologna, Italy
Giorgia Cinelli Tore Tollefsen Marc de Cort
European Commission, Joint Research Centre (JRC), Institute for Transuranium
Elements (ITU), Nuclear Security Unit, Ispra (VA), Italy
European Atlas of Natural Radiation
MAPS STATUS NOTES
Indoor Radon - EIRM advanced 26 countries!!
Geogenic Radon - EGRM first version Improvements:
Multivariate approach
Cosmic radiation first version
Terrestrial gamma dose rate - TGDR in progress Estimation from
EURDEP data
U, Th and K in soil and bedrock in progress
Outdoor radon in discussion phase
Water (ground and surface water) in discussion phase
Total dose by natural radiation in discussion phase Extensive modelling &
additional spatial
demographic data needed
THE REAL BEDROCK
30 cm
Matteo Verocai, BSc 2011
TOOLBOX
• Geological maps. Where the bedrock units
are (GU, Geological Units)
– OneGeology
• Whole-rock U-Th-K data to assign to GUs
– EarthChem
Cinelli et al. 2015
BEDROCK LITHOLOGY
BEDROCK LITHOLOGY
> 60 GUs
• It’s a IEDA
Interdisciplinary Earth
Data Alliance initiative
• Community-based, on
voluntary basis
• Data to be discovered
and reused by a diverse
community now and in
the future.
EarthChem
EarthChem
> 55 000 samples for Europe (> 850k World)
AUSTRIA_EarthChem
• 111 data
• 33 with U
• 5 locations
• > 1100 data
• Igneous rock
bias
SPAIN_EarthChem
OneGeology & EarthChem
A DISMAL PERFORMANCE ?
• OneGeology
– Too many GUs
• EarthChem
– Lots of data but clustered
– Sedimentary rocks (limestone, sandstone…)
are underrepresented
A MODIFIED APPROACH
• Starting point: national geological maps
(1:1M or 1:2M)
• Discard
– Quaternary (not solid rock)
– Ultramafics (not enough U Th K; Braga & Cinelli,
Ofioliti 2014)
• GUs by lithostratigraphy
https://www.geologie.ac.at/
23 GUs
(1:2M)
AUSTRIA
• Lithostratigraphy
• ≈ 20 GUs
• Maintain bedrock
complexity
• Merge the 1G
units into ≈ 20
GUs
• Chronostratigraphy
• > 40 GUs
• in 1G ≈ 140
• Group by similar
lithology
SPAIN
U-Th-K DATA
• Igneous + metamorphic rocks
– EarthChem + geoscience literature
• Sedimentary rocks
– Literature; not many data
• Processed ≈ 3000 data (Austria)
• U-Th-K averages for each GU
BEDROCK MAP vs. TGDR
Bossew et al.,2015
Based on Visual Analysis
Natural gamma radiation map of
Spain. Quindós et al. (2004).
Based on Visual Analysis
Umhausen
Uranium MAP vs. RnRiskMap
• Radon Risk Map
(indoor Rn)
Courtesy of Valeria Gruber
CONCLUSIONS
• A (imperfect) method for U-Th-K bedrock
maps
• Gamma Rad maps and indoor Rn
preserve bedrock signature
• U-Th-K for Sed Rocks – a problem
• Literature check = time consuming
T. Plank
The Chemical Composition of Subducting Sediments
http://dx.doi.org/10.1016/B978-0-08-095975-7.00319-3
U-Th-K SED ROCK
• An open question
• Today’s sediments
U-Th-K signature ≈
sedimentary rock
• In similar
depositional
environment