Early Jurassic Biogeography of the Arctic

By

B.L. Nikitenko (Institute of Petroleum Geology of SB RAS), B.N. Shurygin (Institute of Petroleum Geology of SB RAS), and M.B. Mickey (Micropaleo Consultants, Inc.)

Data on the geographic distribution of Early Jurassic benthos analyzed here are difficult to compare. Patterns of benthos communities for certain intervals have been investigated, the quantitative taxa proportions as well as dynamics of taxonomic variation during the Jurassic have been analyzed and etc. The authors have also used some published data on the distribution of Early Jurassic benthos for Arctic, although these publications often lacked quantitative information on benthos communities.

In the Arctic Realm only benthos taxa of very wide geographic distribution have been found, with some rare Arctic endemic taxa being revealed. The traditional principles of paleobiogeographic zonation based on the nekton (definition of the Realms and Regions based on endemic taxa) can not be used for benthos. Therefore at the biogeographical zonation on benthos it is necessary to use principles of historicism and statistical analysis.

Analysis has been carried out using genera as the taxonomic operational unit, as opinions on the classification of some species vary considerably in different publications, while nomenclature of genera are more standard. The data on presence/absence of characteristic foraminifera, ostracod and bivalve genera have been treated by multivariate analysis (Jaccard cluster analysis).

 As a result, a number of biogeographic units based on foraminifera, ostracoda and bivalve date have been established for several levels in Early Jurassic for Arctic and North of Boreal-Atlantic Realms. The boundaries of the Provinces and Realms based on paleogeographic distribution of different groups of benthos change their position during geological time.

AAPG Search and Discovery Article #90008©2002 AAPG Pacific Section/SPE Western Region Joint Conference of Geoscientists and Petroleum Engineers, Anchorage, Alaska, May 18–23, 2002.