PALEONTOLOGICAL DATABASE APPLICATIONS FOR ALASKAN TERRANE STUDIES

A web-based paleontological database is currently being constructed for the State of Alaska, the first such state to be the subject of a complete inventory of extant paleontological data. The data consists of thousands of unpublished, internal USGS fossil reports (known as E&R reports), published paleontological and geological reports, as well as unpublished oil and mining company reports. While not taxonomic per se, these reports are often the only means to document the occurrence of certain taxa.

Most of Alaska is composed of accreted terranes whose differentiation until recently has been based primarily on structural and stratigraphic differences. Analysis of this voluminous fossil data also delineates significant differences in taxic composition of the various terranes, and provides yet another strong tool to indicate differences and affinities between the various terranes forming the collage of present-day Alaska.

Examples are provided from the Upper Triassic of Alaska. Certain faunal elements such as the middle to late Norian hydrozoan Heterastridium are revealed to be widespread, occurring in all accreted terranes of southern Alaska (Wrangellia, Alexander, Farewell, Chulitna, and Peninsular) as well as cratonic east-central Alaska (its farthest north occurrence on the North American craton), whilst it is completely absent from the Arctic Alaska terrane, suggesting a relatively high (cool-water) paleolatitude setting for the latter. The distributional patterns of other faunal groups, most notably the gastropods, indicate that some southern Alaskan terranes, such as Wrangellia and Alexander terranes, were separated by a significant enough distance that some gastropod groups, notably those characterized by direct development, share no common elements, whilst other groups such as certain neritimorph taxa characterized by a long-lived planktotrophic larval stage, are present in both terranes. Scleractinian corals, spongiomorph hydrozoans, and sphinctozoid sponges also are among the Alaskan faunas and appear paleogeographically useful.

Database compilations of these and other faunal elements generated from USGS collections and reports, demonstrate the utility of the database in both terrane analyses and circum-Pacific correlations.