UNUSUAL NORMAL ALKANE DISTRIBUTIONS IN OFFSHORE NEW-ZEALAND SEDIMENTS

The occurrence of unique even-carbon dominated normal alkanes in sediment extracts was confirmed in sediments from the eastern continental shelf offshore of North Island, New Zealand in Hawke Bay. The range in carbon chain-lengths was from n-C16 to least n-C36, extending distributions well beyond the previously reported 24 carbons. Stable isotope analysis of individual alkanes suggest an independent origin for the odd and even n-alkanes. It is suggested that sedimentary even number n-alkane predominances are more widespread than previously thought but go unrecognized due to substantial overprinting by terrestrial derived odd carbon number n-alkanes. © 1990.