Abstract: The International Commission on Stratigraphy: Purpose, Goals, and Recent Progress Illustrated by Work on the Ordovician and Neogene Systems

FINNEY, STANLEY, California State University, Long Beach, Long Beach, CA

The statutory objectives of the International Commission on Stratigraphy under IUGS are development of a standard global stratigraphic scale, definition and correlation of its subdivisions, and establishment of their boundaries. The necessity for a precise global chronostratigraphic scale is obvious. Research on global events means comparison of stratigraphic documents from distant regions. To achieve its objectives, 14 Subcommissions and various Boundary Working Groups of the ICS have been working for more than 25 years to elaborate and correlate standard global Systems, Series, and Stages, and a major part of this work has been to define boundaries between them. Work on some systems, such as the Silurian and Devonian, is complete, but global series and stages have yet to be formally defined for other systems, such as the Cambrian. The apparent lack of progress reflects many factors, including scientific disagreements, faunal provincialism, taxonomic and regional (or national) biases, and the minimal funding available to support investigations of candidate stratotype sections. Nevertheless, an impressive information base has been compiled on stratigraphic successions worldwide. The present status of ICS activities is well illustrated by the recent accomplishments of the Subcommissions on the Ordovician and Neogene Systems.

Marked provincialism and ecological differentiation of Ordovician faunas resulted in the development of several regional subdivisions of the Ordovician System and greatly hindered progress towards establishment of a single, standard framework of global Series and Stages. After many years of debate, the Ordovician Subcommission selected six key global biohorizons on which to define global Series and Stages, and the Subcommission is now progressing rapidly with formal votes on GSSPs (global stratotype sections and points).

Much more progress has been made on the Neogene. Series are formally defined, and so too are Stages of the upper Miocene and the Pliocene. Of particular importance is the fact that Stage (and Series) boundaries are defined not only on standard bio stratigraphy but also magnetostratigraphy and astrocyclostratigraphy, allowing for global correlation with resolution of less than 20,000 years.

AAPG Search and Discovery Article #90911©2000 AAPG Pacific Section and Western Region Society of Petroleum Engineers, Long Beach, California