Paleomagnetic evidence for a megabreccia horizon in the Upper Jurassic sequence of Eperkés Hill, Transdanubian Range, Hungary

Abstract

Eperkes Hill is a thoroughly studied classic exposure, yet its facies interpretation is still debated. The issue is whether Upper Triassic - lowermost Jurassic carbonates are beds or blocks embedded within the Kimmeridgian-Berriasian limestone. The answer to this question is important for the interpretation of the structural evolution and paleogeography of the Transdanubian Range area at the Jurassic-Cretaceous boundary; we decided therefore to contribute to the solution by applying paleomagnetism to the problem. We tested several beds and suspected olistoliths from two artificial exposures. In order to check the consistency of the paleomagnetic signal on site level, we drilled three or more cores from each, and subjected them to standard paleomagnetic laboratory processing and evaluation. We found that magnetic parameters were distinctly different for regular beds and for suspected olistoliths, but that the paleomagnetic signal was consistent within every site. However, between-site c...