Oligocene laminated limestones as a high-resolution correlator of palaeoseismicity, Polish Carpathians

Thin intercalations of laminated coccolith limestones in a series of flysch and black shales define a regional marker horizon in the Oligocene strata of the Outer Carpathians. Distinctive sequences of laminae in the coccolith limestones have been correlated over distances of up to 240 km and across major facies zones. The correlated succession of laminae provided the basis for correlation of intercalated turbidites. The successions of laminae are disturbed at all studied localities by erosional gaps, intercalations of non-laminated limestone and deformation of some intervals of the laminated sequence. The disturbances themselves have been precisely correlated between three major nappes of the Outer Carpathians. The characteristics of the disturbances and their long-distance continuity indicate their seismic origin. The coccolith ooze at the top of the sediment column was firm and its simultaneous disturbance over large areas required earthquakes of magnitudes above 6.5. Laminated pelagic limestones provide a precise chronostratigraphic framework for long-distance correlation of seismic and other events recorded within their sequence.