Magnetic polarity stratigraphy and correlation of the Leisey Shell Pits, Hillsborough County, Florida

Abstract

Oriented paleomagnetic samples were collected from plaster jackets containing fossils, in situ bivalves, and surrounding matrix from the Leisey Shell Pit. Analysis in the paleomagnetic laboratory indicates that the magnetization is probably carried in fine-grained magnetite. After both alternating field and thermal demagnetization, all of the five sites sampled are interpreted to be of reversed polarity fo6r the local section at Leisey. In conjunction with the stage of evolution of the fossil mammals and interbedded Sr isotopic data, the Bermont Formation in the area of Leisey correlates to the late Matuyama Reversed Chron between about 1.66 and 1.4 Ma.