Abstract Details

Details of the Abstract

Title of paper Nature of crustal electrical conductivity anomalies in the Central Norwegian Caledonides and similarity to analogous anomalous conductivity features in the Alpine-Carpathians.
List of authors Kovacikova, S., Hill, G.J., Gradmann, S., Jakob, J., Vozar, J., Bezak, V., Kamm, J., Mishra, P., Klanica, R., Smirnov, M., Rydman, O.,
Affiliation(s) Institute of Geophysics, Acad. Sci. Czech Republic, Bocni II/1401, Praha 4-14131, Czech Republic,
Institute of Geophysics, Acad. Sci. Czech Republic, Bocni II/1401, Praha 4-14131, Czech Republic,
Geological Survey of Norway, Leiv Eirikssons vei 39, 7040 Trondheim, Norway,
Geological Survey of Norway, Leiv Eirikssons vei 39, 7040 Trondheim, Norway,
Earth Science Institute, Slovak Acad. Sci., Dúbravská cesta 9, 840 05 Bratislava, Slovakia,
Earth Science Institute, Slovak Acad. Sci., Dúbravská cesta 9, 840 05 Bratislava, Slovakia,
Geological Survey of Finland, P.O. Box 96, 02151 Espoo, Finland,
Geological Survey of Finland, P.O. Box 96, 02151 Espoo, Finland,
Institute of Geophysics, Acad. Sci. Czech Republic, Bocni II/1401, Praha 4-14131, Czech Republic,
Lulea University of Technology, 97187 Luleå, Sweden,
Lulea University of Technology, 97187 Luleå, Sweden,
Summary A dense network of broadband magnetotelluric data in the period range of 10-3-103s was collected during two field campaigns in 2022-2023 covering the Trondelag area, central Norway as a part of the D-Rex project (Deposit to Regional-scale Exploration) to investigate the lithospheric structure of the central Norwegian Caledonides, and how they relate to the near-surface mineraliyation. 3D inverse modelling of the MT responses revealed complex 3D electrical electrical structure. The target area lies within the Caledonian allochtonous nappes, which mark a detachment from the original Precambrian Svecokarelian and Sveconorwegian basement and has undergone tens to hundreds of km(s) of lateral transport. The conductivity distribution appears to be controlled by local morphology. However, pronounced conductivity anomalies are observed at the mid-crustal depths of the Precambrian basement, beneath the nappe structures, which are connected to near-surface conductive features associated with known Cu-Zn deposits by sub-vertical conduits intersecting the basement/thrust boundary. This fits into the mineral system concept with deep-seated relict sources, fossil mineral-bearing fluid pathways and ore deposits themselves. In this context, a similarity with crustal conductors in other, even much younger orogenic regions can be noticed. In the Carpathian branch of the European Alpine orogene, a similar chain of anomalous features appears in the crust beneath the system of nappes. This well-known Carpathian conductivity anomaly is associated with a shear zone that also functions as a channel for fluids migrating from the mantle and forming conductive mineral accumulations near the Earth's surface.
Session Keyword 3.0 EM methods for exploration (geothermal, mineral resources, etc.)
File upload 3.0_nature_of_crustal_electri_kovacikova_01.pdf
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