Open AccessPalaeomagnetic and rock magnetic study of Devonian olistoliths set in early Carboniferous flysch, West Sudetes, Poland
Author(s) -
Jeleńska Maria,
Aı¨fa Tahar,
Ką Magdalena,
Żelaźniewicz Andrzej
Publication year - 2001
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1046/j.0956-540x.2001.01448.x
Subject(s) - carboniferous , geology , flysch , devonian , paleontology , paleozoic , paleomagnetism , baltica , permian , slumping , ordovician , sedimentary rock , structural basin
Summary The Upper Devonian greywacke, mudstone and limestone olistoliths from the Zdanów‐Bardo‐Młynów (ZBM) allochthonous complex of the Góry Bardzkie (GB), West Sudetes, have been sampled for palaeomagnetic investigations (46 hand samples and 30 drill cores from seven sites). The random distribution of the olistolithic blocks within early Carboniferous flysch provides an opportunity for the megaconglomerate test. Microscopic and rock magnetic studies showed that pyrrhotite and magnetite are the carriers of magnetic remanence. Thermal and AF demagnetization revealed four components of characteristic remanence. The C‐component, found in one site only, yields an in situ pole position of 19°S, 340°E, close to early Carboniferous data for Baltica. The P‐component, also found in one site, yields an in situ pole position of 42°S, 339°E, which coincides with late Permian poles for Baltica. The R‐component of moderate inclinations and northwesterly and northeasterly declinations, found in all but one site, is probably partial remagnetization of a Devonian component during Carboniferous and Permian times. The D‐component found in all sites shows significant dispersion of declination of site‐mean directions in geographical and stratigraphic coordinates, but inclinations after tilt correction are consistent with inclinations expected for the Middle–Late Devonian calculated for the Sudetes from the palaeopoles for Baltica. Significant dispersion of declination is expected for primary magnetization of olistoliths distributed at random within flysch. The fold test for inclination only, applied to the site‐mean directions of the D‐component for the ZBM complex, is positive. The D‐component is therefore interpreted as representative of the Middle–Late Devonian local field inclination. The calculated palaeolatitudes, 15°S–7°S, indicate that the West Sudetes were positioned in that time at the same latitude as the southwestern margin of Baltica.