Geomagnetic polarity stratigraphy and nannofossil biostratigraphy at the K/T boundary section near beloc, Haiti

A 54-meter-thick stratigraphic section of limestone and chalk from the Cretaceous and Tertiary Beloc Formation in southern Haiti is correlated to the geomagnetic polarity time scale using paleomagnetic and nannofossil data. The controversial K/T boundary layer at Beloc occurs within a thick zone of reversed magnetic polarity correlative to chron C29r (from 18 m above to 25 m below the layer). The Tertiary part of the section is confined to the Markalius inversus nannofossil Zone (NP1). Micula murus first occurs between 26.50m and 28.05 m below the base of the K/T layer within a zone of normal polarity which we correlate to chrons C30n/C31n combined. Chron C30r is probably too brief to have been recorded in this part of the section. These correlations to the geomagnetic polarity time scale suggest a change in average sedimentation rate at the Beloc section from 2.0 or 3.5 m/m.y. to >41 m/m.y. at the beginning of C29r time.