Paleomagnetic Dating of Lava Flows of Uncertain Age, Somma-Vesuvius Volcanic Complex (Southern Italy)

Abstract

Detailed paleomagnetic and rock magnetic studies of 14 previously undated lava flows from the Somma-Vesuvius volcanic complex were undertaken. The magnetic carriers consist of Ti-poor titanomagnetites typified by pseudo-single domains. Characteristic magnetization directions determined from detailed stepwise alternating field and thermal demagnetizations gave well-defined mean directions for each flow unit. Paleodirections for 10 of the 14 lavas appear to be related to the early 17th century segment of the Italian paleosecular variation reference curve; thus their ages are easily retrieved. The remaining four sites yielded distinct mean directions, which cannot be simply correlated to any given sector of the reference curve, within the time frame expected for the activity. The paleomagnetic directions for these lavas may correspond to time intervals outside the period covered by the reference secular variation curve, or they may reflect local structural disturbance and have no geomagnetic significance.