RESOLVING SEDIMENTOLOGICAL UNCERTAINTIES USING MAGNETOSTRATIGRAPHIC CORRELATION - AN EXAMPLE FROM THE MIDDLE JURASSIC OF BURGUNDY, FRANCE

Magnetostratigraphic analysis was undertaken on a core 85 m long core from the shallow-water carbonate platform of Bathonian to late Callovi an age in Burgundy, France, to establish high-resolution magnetic corr elations in a succession devoid of good stratigraphic markers and with diachronous lithofacies. Magnetic extracts reveal that the magnetic m inerals carrying the characteristic remanence are mainly detrital tita nomagnetites and fine-grained biogenic magnetite of probable bacterial origin, Comparison of magnetic properties with Lithologic data from w ireline logs indicates that large grains are predominant in marly depo sits whereas fine-grained minerals are common mainly in pure limestone s, We have established a polarity sequence for the core that is indepe ndent of lithology and includes 17 polarity zones, With the help of fa unal zonation based on brachiopods and ammonites, the polarity sequenc e was compared with the magnetostratigraphy established previously in four other sections from the same area, The magnetostratigraphic corre lation corroborates that platform flooding occurred during the early C allovian, an age in agree ment with biostratigraphic interpretation co nstraining the age of successive onlaps. A characteristic reverse pola rity interval within the ammonite Calloviense subzone is present in al l the cores, confirming the utility of magnetostratigraphy for stratig raphic correlation studies throughout the Paris Basin and Burgundy.