Stephen A. Schellenberg

San Diego State University

Upper-division majors to graduate level

Fundamentals of biostratigraphy and magentostratigraphy; basic literacy in excel; familiarity with ocean drilling helpful but not critical.

Stand-alone investigation with follow-up group discussion and comparison of results.

Production and comparison of age models based on different microfossil and paleomagentic data from ocean drilling

Generate age models from discrete data; compare taxon-specific and "total evidence" age models

Data management; Excel proficiency

After exposure to the basic concepts of biostratigraphy and magnetostratigraphy, participants apply these concepts to produce a biomagnetostratigraphic age model using microfossil and paleomagnetic data from a Paleogene core recovered from Walvis Ridge in the South Atlantic (Ocean Drilling Program Site 1262). The investigation has three parts: First, observed first and last occurrences of various planktonic foraminifera species at different core depths are given absolute ages through reference to the Berggren et al. (1985) time-scale. Second, these planktonic foraminiferal data are used to identify magnetic reversals within the same core and thereby assign absolute ages to these events. Third, the resulting biomagnetostratigraphic age model is used to estimate the time between two well-documented "hyperthermals" within the core, the Paleocene-Eocene Thermal Maximum (PETM) and the Eocene Layer of Mysterious Origin (ELMO). The investigation illustrates how biostratigraphy and magnetostratigraphy complement one another and together provide an operational time-domain for all subsequent studies, be they paleoceanographic, evolutionary, etc. Note that this investigation operates on an established timescale (i.e., Berggren et al, 1985) and does not explictly demonstrate how such timescales are developed. Thus, instructors are encouraged to have students construct a simple composite relative time scale from basic outcrop data prior to this investigation.

Comparison and evaluation of resulting age models and answers to related questions.

http://www-odp.tamu.edu/publications/leg_ndx/208ndex.htm