BARRON, JOHN A., U.S. Geological Survey, Menlo Park, CA

ABSTRACT: The Unique Contribution of Biostratigraphy: Getting It Across

Refined techniques for the acquisition and processing ofgeophysical and geochemical data (wire line logging, seismic stratigraphy, stable isotope records, etc.) and the advent of computer work stations and software have brought a revolution to stratigraphy and to the construction of regional geohistories. Treatment of micropaleontologic data (biostratigraphic and paleoenvironmental) has lagged behind these advances, because acquisition of such data is labor intensive and usually not quantitative. Basically, it is difficult to make reproducible curves of micropaleontologic data, and it is doubly difficult forthe non-specialist to assess the quality of the data set. Micropaleontologists have added to this problem with internal arguments about taxonomy, as well as how to interpret biostr tigraphic and paleoecologic data. Such is the nature of largely descriptive disciplines such as micropaleontology. Unlike most other types of stratigraphic data (lithology, wire line logs, seismic records, etc.), however, microfossil assemblages normally go through unique, nonrepetitive changes with time (ie., Miocene assemblages are distinct from Pliocene assemblages). Because of this fact, microfossil data can reveal vital information which other types of stratigraphic data cannot, such as the presence or temporal extent of unconformities. In addition, microfossils are sensitive environmental indicators. Thus, micropaleontologic data can provide critical time calibration to geophysical and geochemical stratigraphic data, such as revealing which sequence boundary is really present or wh ther an isotopic shift is associated with an unconformity.

Micropaleontologists are faced with the challenge of both streamlining the acquisition of their data and refining its ability to estimate geologic time and determine the paleoenvironmental setting. The first task can be lessened through a better understanding of how geophysical and geochemical stratigraphic data is acquired and interpreted. Conflicts in correlation might then be resolved, and key stratigraphic intervals might be selected for more thorough micropaleontologic study. Such an integrated study of the various types of stratigraphic data will certainly lead to better refinement of geologic time and past environments. In pursuing these tasks, it is now more important than ever to promote active communication between micropaleontologists on the taxonomy of key taxa and their b ostratigraphic, and paleoecologic interpretation. Such communication

will undoubtedly benefit from graphical and pictorial representations of micropaleontologcial data on the computer, but it also requires well-trained and experienced micropaleontologists.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.