Mesozoic remagnetization of Upper Devonian carbonates from the Česis and Skaistgirys quarries (Baltic states)

Abstract

The palaeomagnetic properties of Frasnian and Famennian dolomites from two quarries in Latvia and Lithuania respectively are compared. Famennian dolomites from Skaistgirys quarry (N Lithuania) revealed the presence of one distinct normal polarity component (D =14o , I = 53o , a 95 = 4.2o , n = 28 specimens). The reversed polarity component predominates in Frasnian dolomites from Česis quarry (Central Latvia). Only one hand specimen from this locality contained a component with the opposite direction. The mean direction from Česis quarry (D = 198°, I = -53°, a 95 = 4.4°, n = 22 specimens) is very close to that from Skaistgirys quarry and therefore was recorded most probably during the same event of remagnetisation but at a later stage. The remagnetizations of these dolomites were caused most probably by progressive oxidation of ferric sulphides to magnetite and finaly to hematite. A comparison of the palaeomagnetic poles obtained with the stable European APWP (Apparent Polar Wander Path) indicates a Late Jurassic/Early Cretaceous age for the remagnetization event. This estimation can be useful for chronostratigraphic linking of post-Palaeozoic tectonic activity and diagenetic events, so far very poorly recognized in this part of the European plate. Our data shows also that the Late Jurassic/Early Cretaceous part of the stable European APWP may still be inaccurate.