PALEOMAGNETISM AND ROCK MAGNETISM OF THE TORTONIAN-MESSINIAN BOUNDARY STRATOTYPE AT FALCONARA, SICILY

The Tortonian-Messinian boundary stratotype at Stazione Falconara (Sicily) yields normal polarity remanent magnetizations of post-tilting age, implying that the entire section is (sub)recently remagnetized. The absence of direct time control on the biostratigraphic datum levels in the section makes it therefore less suited as a boundary stratotype section. Existing age estimates for the Tortonian-Messinian boundary are discussed; it is concluded that an age of 5.6 Ma is at present the best estimate. Assessment of the magnetic mineralogy in the Falconara section shows that rock magnetic parameters are for a large part lithologically controlled. A second important controlling factor is the numerous joints, which could have acted as channels for circulating groundwater and from which predominantly (sub)recent finely crystalline haematite was precipitated. possibly mediated by weathering processes. This haematite has completely replaced an earlier and presumably magnetite-dominated magnetic mineralogy.