Paleomagnetism and paleogeography of Jurassic radiolarian cherts from the northern Apennines of Italy

Oriented samples of Jurassic radiolarian chert were collected from the Tusc an domain (continental margin) and the Ligurid domain (oceanic) of the nort hern Apennines for paleomagnetic study to determine the paleogeographic ori gins of these rocks. The oceanic rocks are all thermochemically overprinted by a mostly reversed-polarity component of magnetization (B) that was like ly acquired during late Miocene regional uplift of the northern Apennines, This component also dominates the lower brittle chert of the Tuscan Cherts, but disappears upsection in the more clay-rich and ductile siliceous marls tones, In addition, the Tuscan Cherts retain an inferred primary magnetizat ion (C), isolated at temperatures between 560 and 660 degreesC, which passe s a fold test and shows a polarity stratigraphy. This component indicates a paleolatitude of 11 degrees +/- 4 degreesN, and a counterclockwise vertica l-axis rotation of 29 degrees +/- 9 degrees with respect to the southern Al ps of Italy, of 49 degrees +/- 8 degrees with respect to Africa, and of 91 degrees +/- 8 degrees with respect to Eurasia, Our results suggest that the Tuscan domain was farther south than other deep-water continental margin s ections of Adria, and that transcurrent faulting might have played a signif icant role in the orogenic evolution of the northern Apennines.