Magnetic mineralogy and paleomagnetism of serpentinized ultramafic rocks from the Braszowice–Brzeźnica fragment of Sudetic paleozoic ophiolite

• Autorzy: Kądziałko-Hofmokl, M. , Jeleńska, M. , Delura, K. , Bylina, P.
• Języki publikacji: EN

Abstrakty

EN

Complex paleomagnetic, rock-magnetic and mineralogical studies were performed on serpentinized utramafic rocks from Braszowice– Brzeźnica massif (BB) situated at the southern extremity of the Niemcza Shear Zone, close to the Sudetic Marginal Fault. Studies of magnetic minerals revealed presence of several varieties of magnetite grains, and partly altered Cr-spinels. Paleomagnetic studies revealed stable component HS of natural remanence carried by magnetite formed probably during the initial serpentinization. The directions of HS have good grouping within each locality, but differ between localities. Studies of anisotropy of magnetic susceptibility (AMS) have shown that directions of anisotropy axes are steep instead of horizontal as is common within the Niemcza Shear Zone. Taking advantage of the directions of AMS we rotated the directions of HS and brought them to the reference direction for the Sudetes for 372 Ma. We suggest that after acquiring AMS and HS during the Upper Devonian, the BB became divided into multiple units due to tectonic activity in the region.

Słowa kluczowe

EN

Sudetes; Paleozoic; ophiolite; tectonic rotations

• Czasopismo: Acta Geophysica
• Rocznik: 2010
• Tom: Vol. 58, no. 2
• Strony: 269-299
• Opis fizyczny: Bibliogr. 27 poz.

Twórcy

autor

Kądziałko-Hofmokl, M.

autor

Jeleńska, M.

autor

Delura, K.

autor

Bylina, P.

• 1Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,

Bibliografia

• Badura, J., W. Zuchiewicz, A. Górecki, W. Sroka, B. Przybylski, and M. Żyszkowska (2003), The Sudetic Margina Fault, SW Poland, in the light of morphometric studies, Geolines 16, 13-14.
• Barnes, S.J. (2000), Chromite in komatiites, II. Modification during greenschist to mid-amphibolite facies metamorphism, J. Petrology, 41, 3, 387-409,
• Barnes, S.J., and P.L. Roeder (2001), The range of spinel compositions in terrestrial mafic and ultramafic rocks, J. Petrology, 42, 12, 2279-2302,
• Besse, J., and V. Courtillot (2002), Apparent and true polar wander and the geometry of the geomagnetic field over the last 200 Myr, J. Geophys. Res. 107, B11, 2300,
• Bröcker, M., A. Żelaźniewicz, and M. Enders (1998), Rb-Sr and U-Pb geochronology of migmatitic gneisses from the Góry Sowie (West Sudetes, Poland): The importance of Mid-Late Devonian metamorphism, J. Geol. Soc. London, 155, 6, 1025-1036,
• Bylina, P., E. Dubińska, A. Kozłowski, W. Dörr, K. Nejbert, and J. Schastok (2001), Glimmerite from Potoczek (Góry Sowie, SW Poland): Record of ultramafic body emplacement into migmatitic gneisses, Mineral. Soc. Poland – Spec.Pap. 19, 30-32.
• Delura, K. (2005), Magnetite-nickel sulphides-awaruite association in serpentinites from Braszowice-Brzeźnica massif (Sudetic ophiolite, SW Poland), Mineral.Soc. Poland – Spec. Pap. 26, 149-152.
• Dubińska, E., P. Bylina, A. Kozłowski, W. Dörr, K. Nejbert, J. Schastok, and C. Kulicki (2004), U-Pb dating of serpentinization: Hydrothermal zircon from a metasomatic rodingite shell (Sudetic ophiolite, SW Poland), Chem. Geol. 203, 3-4, 183-203,
• Dunlop, D.J. (2002a), Theory and application of the Day plot (Mrs/Ms vs Hcr/Hc): 1. Theoretical curves and tests using titanomagnetite data, J. Geophys. Res.107, B3, 2056,
• Dunlop, D.J. (2002b), Theory and application of the Day plot (Mrs/Ms vs Hcr/Hc): 2. Application to data for rocks, sediments and soils, J. Geophys. Res. 107, B3, 2057,
• Dunlop, D.J., and B. Carter-Stiglitz (2006), Day plots of mixtures of superparamagnetic, single-domain, pseudosingle-domain and multidomain magnetites, J. Geophys. Res. 111, B12S09,
• Gunia, P. (1986), Rodigite from serpentinites of the vicinity of Mikołajów (serpentinite massif of the Braszowice-Brzeźnica, Lower Silesia), Geol. Sudetica 21, 1, 197-211 (in Polish).
• Gunia, P. (1992), Petrology of the ultrabasic rocks from the Braszowice-Brzeźnica Massif (Fore-Sudetic Block), Geol. Sudetica 26, 119-167 (in Polish).
• Gunia, P., and S. Mazur (1992), Brittle deformation of ultrabasic rocks in the Braszowice-Brzeźnica Massif (Lower Silesia, Poland), Bull. Pol. Acad. Sci.,Earth Sci. 40, 3, 1291-202.
• Jelenska, M., M. Kędziałko-Hofmokl., J.B. Edel, L. Jamrozik, N. Petersen, and H. Soffel (1995), Palaeomagnetic investigations of the palaeomagnetic circum-Sowie G\ry Mountains ophiolitic belt in the Sudetes, Poland, Geophys. J. Int. 122, 658-674.
• Jeleńska, M., M. Kądziałko-Hofmokl, and A. Żelaźniewicz (2003), The Devonian–Permian APWP for the West Sudetes, Poland, Stud. Geophys. Geod. 47, 2,
• Jelinek, V. (1977), The Statistical Theory of Measuring Anisotropy of Magnetic Susceptibility of Rocks and its Application, Geofizyka, Brno, 88 pp.
• Kądziałko-Hofmokl, M., M. Jeleńska, P. Bylina, E. Dubińska, K. Delura, and K. Nejbert (2006), Paleomagnetism of Paleozoic ultrabasic rocks from the Sudetes Mts (SW Poland): Tectonic implications, Geophys. J. Int. 167, 1, 24-42,
• Kądziałko-Hofmokl, M., K. Delura, P. Bylina, M. Jeleńska and J. Kruczyk (2008), Mineralogy and magnetism of Fe-Cr spinel series minerals from podiform chromitites and dunites from Tąpadła (Sudetic ophiolite, SW Poland) and their relationship to palaeomagnetic results of the dunites, Geophys. J. Int. 175, 3, 885-900,
• Kryza, R., S. Mazur, and T. Oberc-Dziedzic (2004), The Sudetic geological mosaic: Insights into the root of the Variscan orogen, Prz. Geol. 52, 8/2, 761-773.
• Lewandowski, M., T. Werner, and K. Nowożyński (1997), PDA – a program package of Fortran programs for paleomagnetic data analysis, Inst. Geophys. Pol. Acad. Sci. Manuscript, 1-17.
• Mazur, S., P. Aleksandrowski, R. Kryza, and T. Dziedzic-Oberc (2006), The Variscan Orogen in Poland, Geol. Quart. 50, 1, 89-118.
• Mazur, S., P. Aleksandrowski, K. Turniak, and Awdankiewicz (2007), Geology, tectonic evolution and Late Paleozoic magmatism of Sudetes – an overview, Granitoids in Poland, AM Monograph 1, 59-87.
• Mellini, M., C. Rumoriand, and C. Viti (2005), Hydrothermally reset magmatic spinels in retrograde serpentinites: formation of “ferritchromit” rims and chlorite aureoles, Contrib. Mineral. Petrol. 149, 3, 266-275,
• Pietranik, A., and T.E. Waight (2008), Processes and sources during Late Variscan dioritic-tonalitic magmatism: Insights from plagioclase chemistry (Gęsiniec Intrusion, NE Bohemian Massif, Poland), J. Petrology 49, 9, 1619-1645,
• Werner, T. (2002), The correlation of magnetic anisotropies (AMS and AARM) with tectonic fabrics of the Niemcza shear zone (SW Poland), Acta Geophys. Pol. 50, 1, 79-107.
• Żelaźniewicz, A. (1995), Fore-Sudetic part of the Góry Sowie Block, Ann. Soc.Geol. Pol., Spec. Issue, 66th Ann. Meeting of Pol. Acad. Sci., 85-110 (in Polish with English summary).