Antoni K. Tokarski

Large counterclockwise rotation of the Inner West Carpathian Paleogene Flysch—Evidence from paleomagnetic investigations of the Podhale Flysch (Poland)

Abstract We are reporting the first paleomagnetic results from the Podhale Flysch, which crops out in the area between the Pieniny Klippen Belt and the Tatra Mts., where claystones and mudstones were drilled at 10 localities, mainly from subhorizontal strata. In all cases, the magnetic fabric was found to be typical of undeformed sediments, with well developed magnetic lineation (aligned with the sedimentary transport direction) at some of the localities; the dominant magnetic mineral was identified as magnetite, accompanied by iron sulphides. For six of the localities, with one exception for those with poorly developed lineation, we obtained statistically well-defined paleomagnetic mean directions, on AF or on combined AF and thermal demagnetization. The overall-mean paleomagnetic direction is D=298° 1=53° k=121, a95=6°, in tectonic coordinates. Similar direction was observed for Inner Carpathian flysch from the Levoca basin (Slovakia). We conclude, that the flysch of the two basins must have travelled a few hundred kilometres to the North, after the early Miocene tectonic phase: this displacement was accompanied by about 60° counterclockwise rotation with respect to Stable Europe.

Deformation bands and the history of folding in the Magura nappe, Western Outer Carpathians (Poland)

Abstract Deformation bands ( db ) which are indicative for soft-sediment deformation during the folding of flysch sediments are widespread within the Eocene strata of the Magura nappe. Four types of db have been distinguished: (1) db with no cataclasis of detrital sand grains; (2) db with traces of feldspar cataclasis; (3) db with strong cataclasis of detritic feldspar grains; and (4) db with feldspar and quartz cataclasis. In all types of db , calcite cementation occurred after the formation of the deformation bands. No calcite cataclasis was observed in the deformation bands. The bands developed progressively, from (1) to (4), during and after regional folding. Folding occurred when the host strata were poorly indurated and/or under low confining pressure. The earliest db (bands with no cataclasis) formed contemporaneously with water-escape sheets. We conclude that regional folding started not later than during the deposition of the host strata. Calcite mineralization was introduced into the host strata and into the db along cross-fold joints after the completion of regional folding. Within the studied portion of the Magura nappe, regional folding started not later than during Eocene time. Folding was completed when the host strata were not yet fully indurated, most probably still during the Eocene.

Tectonics of Hank sequence (upper proterozoic) in the eastern part of Eglab massif, reguibat shield (West African craton)

Abstract The Eglab massif is widely considered to have been stabilized by the Eburnean orogeny (> 1.7 G.a.). However, sedimentary rocks of the Hank sequence ( 1.9 G.a.) crystalline substratum in the eastern part of the massif. Moreover, these rocks and their substratum are: (1) thrusted westward along NNE trending, high angle, reverse faults, and (2) shifted by two sets of strike-slip faults, a dextral NE one, and a sinistral SE one. The displacements were accompanied by reactivation of older, NE trending, dextral, strike-slip faults in the substratum. The deformation diminishes westward. It was due to horizontal compression oriented perpendicularly to the Pan-African suture situated 300 km further to the east. The time of deformation is constrained by an angular unconformity between the rocks of the Hank formation and the uppermost Proterozoic (> 595 M.a.) sedimentary rocks which overlie them horizontally. The deformation is referred to the Pan-African orogeny (500–700 M.a.). The discussed region was situated in the far foreland of Pan-African nappes.