This study considers the anomalous gravity and magnetic fields in the Alutaguse petrological–structural domain, eastern Estonia. A 10 km wide local maximum (+6.26 mGal) Bouguer anomaly field was discovered at 58.96°N, 26.61°E from the ground gravity data by the Estonian Land Board in 2010–2011. The ground magnetic field intensity measurements indicated a positive magnetic anomaly of 600 nT, in addition to the local gravity maximum. Based on depth estimations, the centre of the anomaly source is placed at 2500–3000 m within the ~1.8 to 1.9 Ga Svecofennian basement. To provide information on the physical properties of the causative source of the anomalies, the geophysical modelling of potential fields was carried out by testing a number of lithologies as sources. The lithologies considered were the known post-orogenic and anorogenic magmatic intrusions in the Estonian basement, as well as typical metamorphic rocks of the Alutaguse domain. The obtained models indicate that the Luusika feature has a range of densities from 2760 to 2920 kg/m3 and magnetic susceptibilities from 20 000 × 10–6 to 56 000 × 10–6 SI. These models suggest that the Luusika causative source is an intermediate to the mafic rock unit, similar to post-orogenic or anorogenic massifs of the Svecofennian basement of Estonia.
All, T., Puura, V. & Vaher, R. 2004. Orogenic structures of the Precambrian basement of Estonia as revealed from the integrated modelling of the crust. Proceedings of the Estonian Academy of Sciences, Geology, 53, 165–189.
Bogdanova, S., Gorbachev, R., Skridlaite, G., Soesoo, A., Taran, L. & Kurlovich, D. 2015. Trans-Baltic Palaeoproterozoic correlations towards the reconstruction of supercontinent Columbia/Nuna. Precambrian Research, 259, 5–33.
https://doi.org/10.1016/j.precamres.2014.11.023
Ellmann, A., All, T. & Oja, T. 2009. Towards unification of terrestrial gravity data sets in Estonia. Estonian Journal of Earth Sciences, 58, 229–245.
https://doi.org/10.3176/earth.2009.4.02
Ellmann, A., Oja, T. & Jürgenson, H. 2011. Application of space technologies to improve geoid and gravity field models over Estonia. Geodeet, 41, 22–25 [in Estonian].
Gromov, O. 1993. Sostavlenie gravimetricheskikh kart m-ba 1:50 000 i 1:200 000 i magnitometricheskoj karty m-ba 1:200 000 Severo-vostochnoj Éstonii [Report on Gravimetric (1:50 000) and Magnetic (1:200 000) Mapping of Northeastern Estonia]. Geological Survey of Estonia, Tallinn, 67 pp. [in Russian].
Kirs, J., Puura, V., Soesoo, A., Klein, V., Konsa, M., Koppelmaa, H., Niin, M. & Urtson, K. 2009. The crystalline basement of Estonia: rock complexes of the Palaeoproterozoic Orosirian and Statherian and Mesoproterozoic Calymmian periods, and regional correlations. Estonian Journal of Earth Sciences, 58, 219–228.
https://doi.org/10.3176/earth.2009.4.01
Koistinen, T., Klein, V., Koppelmaa, H., Korsman, K., Lahtinen, R., Nironen, M., Puura, V., Saltikova, T., Tikhomirov, S. & Yanovskiy, A. 1996. Paleoproterozoic Svecofennian orogenic belt in the surroundings of the Gulf of Finland. In Explanation to the Map of Precambrian Basement of the Gulf of Finland and Surrounding Area 1:1 Million (Koistinen, T., ed.), Geological Survey of Finland, Special Paper, 21, 21–57.
Koppelmaa, H. 2002. Geological Map of the Crystalline Basement of Estonia. Scale 1:400 000. Explanation to the Map Estonian Version. Geological Survey of Estonia, Tallinn, 32 pp. [in Estonian].
Koppelmaa, H. & Kivisilla, J. 1998. Geological Map of the Crystalline Basement of Northern Estonia. Scale 1:200 000. Explanation to the Map. Geological Survey of Estonia, Tallinn, 33 pp.
Laitakari, I., Rämö, T., Suominen, V., Niin, M., Stepanov, K. & Amantov, A. 1996. Subjotnian: rapakivi granites and related rocks in the surroundings of the Gulf of Finland. In Explanation to the Map of Precambrian Basement of the Gulf of Finland and Surrounding Area 1:1 Million (Koistinen, T., ed.), Geological Survey of Finland, Special Paper, 21, 59–97.
Maasik, V. & Sildvee, H. 1965. Eesti NSV territooriumi maakoore vertikaal-liikumiste uurimine gravimeetrilise meetodiga [The Study of Vertical Movements of the Crust of the Estonian SSR Territory by the Gravimetric Method]. Geological Survey of Estonia, Tallinn, 17 pp. [in Estonian].
Melitskaya, V. I. & Papko, A. M. 1992. Otchet o rezul´tatakh aeromagnitnoj s´´emki masshtabov 1:25 000, 1:50 000 na territorii Éstonii i prilegayushtshego shelfa, provedennoj partiei nr. 49 v 1987–1991 gg. [The Results of Aeromagnetic Mapping by Working Group No. 49 at Scales of 1:25 000 and 1:50 000 on Estonian Territory 1987–1991. Report of Investigation]. Geological Survey of Belarus, Minsk, 75 pp. [in Russian].
Niin, M. 1997. Svecofennian granitoids of the crystalline basement of Estonia; classification on the basis of geological structure, mineral and chemical composition. Bulletin of the Geological Survey of Estonia, 7, 4–40.
Oja, T. 2011. The uplift of the gravity anomaly field near Luusika and its impact on geoid. Geodeet, 41, 26–30 [in Estonian].
Oja, T. 2012. Gravity system and network in Estonia. In Geodesy for Planet Earth, Proceedings of the IAG2009 (Kenyon, S., Pacino, M. C. & Marti, U., eds), International Association of Geodesy Symposia, 136, 315–322.
https://doi.org/10.1007/978-3-642-20338-1_38
Oja, T., Türk, K., Ellmann, A., Gruno, A., Bloom, A. & Sulaoja, M. 2011. Relative gravity surveys on ice-covered water bodies. In Environmental Engineering, The 8th International Conference, May 19–20, 2011, Vilnius, pp. 1394–1401.
Pesonen, L. J., Torsvik, T. H., Elming, S.-Ǻ. & Bylund, G. 1989. Crustal evolution of Fennoscandia – palaeomagnetic constrains. Tectonophysics, 162, 27–49.
https://doi.org/10.1016/0040-1951(89)90355-7
Petersell, V., Talpas, A. & Põldvere, A. 1985. Otchet ob izuchenii zhelezorudnykh formatsii v dokembrii Éstonii [An Investigation of Iron Ore Formations in the Precambrian of Estonia]. Geological Survey of Estonia, Tallinn, 129 pp. [in Russian].
Puura, V. & Flodén, T. 2000. Rapakivi-related basement structures in the Baltic Sea area; a regional approach. GFF, 122, 257–272.
https://doi.org/10.1080/11035890001223257
Puura, V., Klein, V., Koppelmaa, H. & Niin, M. 1997. Precambrian Basement. In Geology and Mineral Resources of Estonia (Raukas, A. & Teedumäe, A., eds), pp. 27–34. Estonian Academy Publishers, Tallinn.
Puura, V., Vaher, R., Klein, V., Koppelmaa, H., Niin, M., Vanamb, V. & Kirs, J. 1983. Kristallicheskij fundament Éstonii [The Crystalline Basement of Estonian Territory]. Nauka, Moscow, 208 pp. [in Russian, with extended English summary].
Sharma, P. V. 1976. Geophysical Methods in Geology. Elsevier, Amsterdam, 428 pp.
Smith, R. A. 1959. Some depth formulae for local magnetic and gravity anomalies. Geophysical Prospecting, 7, 55–63.
https://doi.org/10.1111/j.1365-2478.1959.tb01453.x
Smith, R. A. 1960. Some formulae for interpreting local gravity anomalies. Geophysical Prospecting, 8, 607–613.
https://doi.org/10.1111/j.1365-2478.1960.tb01736.x
Smith, W. H. F. & Wessel, P. 1990. Gridding with continuous curvature splines in tension. Geophysics, 55, 293–305.
https://doi.org/10.1190/1.1442837
