Paleomagnetism of the Kvarner islands, Yugoslavia

Abstract

Nearly 400 samples were drilled at 44 localities from Cretaceous and Eocene carbonates and Eocene flysch, all in para-autochthonous position. As a result of thermal cleaning most of the Cretaceous localities yielded statistically well-defined mean directions. Thus overall means were calculated for the Cretaceous of Cres and Krk islands, respectively (Cres, six localities: D = 308°, I = 45°, k = 26, α 95 = 13.3°, D c = 330°, I c = 48°, k = 33, α 95 = 11.9°; Krk, seven localities: D = 342°, I = 42°, k = 12, α 95 = 17.8°, D c = 348°, I c = 48°, k = 26, α 95 = 12.1°). These directions, corrected for tilt, agree well with those determined for rocks of similar age from the fold belt north of “autochthonous’ Istria, the Trieste Karst and the Southern Alps, while exhibiting clockwise rotation of about 30° with respect to the rigid part of the Adriatic region. The natural remanent magnetization (NRM) of most of the Eocene sediments was either too weak to be cleaned properly or became erratic before characteristic remanent magnetization (ChRM) could be isolated. The mean directions of the Eocene localities with ChRM differ so much, both before and after tectonic correction, that an overall mean was not calculated. Despite the scatter, certain trends could be recognized. Counter-clockwise rotation characterizes most of the Eocene sites. The two sites in Krk with clockwise rotation may belong not to the Dalmatian but the High Karst zone.