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Paper No. 6
Presentation Time: 8:00 AM-6:00 PM


COLLINS, Laurel S.1, OGG, James G.2, AUBRY, Marie-Pierre3, BERGGREN, William A.4, COATES, Anthony G.5 and PLETKA, Crystal R.1, (1)Department of Earth and Environment, Florida International University, Miami, FL 33199, (2)Earth and Atmospheric Sciences, Purdue Univ, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051, (3)Department of Geological Sciences, Rutgers University, Wright Labs, 610 Taylor Rd, Piscataway, NJ 08854-8066, (4)Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole Road, Woods Hole, MA 02593, (5)Smithsonian Tropical Research Institute, STRI Unit 9100 Box 0984, DPO AA, 34002-9998, Panama,

Accurate ages for paleontological collections can be difficult to maintain through frequent revisions of geologic time scales, which result from changes to geologic ranges and the taxonomy of index fossils, new correlations of biozonation with paleomagnetics, and improved isotopic dates and changes to calibration standards. The higher the age resolution used for a collection, the more rapidly ages become outdated; and for long-term fossil collecting projects like the Panama Paleontology Project (PPP), consistent age assignments become increasingly problematic as collections grow. The PPP’s program of collecting macro- and microfossils for paleobiologic research began in 1986, and all the collections will ultimately reside in large museums. The ages are based on planktic foraminifera and calcareous nannofossils using a global microfossil zonation and biochronology that has changed over 25 years through large time-scale revisions. Updates, enhancements, and calibrations of microfossil datums and zones in the International Committee on Stratigraphy (ICS) time scale occur too frequently for manual updates.

Our project establishes a way to update ages of fossil collections in perpetuity, as follows: 1) Samples and sampling sites are stratigraphically ordered in meter-scaled sections. 2) Samples yielding age-diagnostic microfossils are identified as age-control levels. 3) Age conflicts and inconsistencies are resolved. (!) 4) Age ranges of the microfossils are entered in a file compatible with the ICS’s TimeScale Creator (TSC, 5) “Lookup” or reference tables in the PPP Database and TSC are linked to generate a set of age-limits for the microfossils comprising the age-control levels; a consistent minimum age-limit range is computed for assignment to a microfossil zone and geologic stage. 6) Ages and uncertainties of intervening samples are interpolated or extrapolated from the age-control levels and a “mean” age model for zone/stage boundaries is generated for the section. 7) The meter-scaled section and age-model section are displayed by TSC’s visualization system; the age-model version allows testing facies trends among sections. 8) As ages change in the lookup tables or new microfossils are identified in samples, a new age model and set of graphics are recomputed for the section.

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