THE IMPORTANCE OF TIME AND TIME SCALES IN SEQUENCE STRATIGRAPHY: APPLICATION OF A CHRONOSTRATIGRAPHIC DESIGNATION SYSTEM FOR PHANEROZOIC DEPOSITIONAL SEQUENCES (Invited Presentation)

Continuing modification of geologic time scales as a function of improvements in age resolution necessitates use of a chronostratigraphic designation system that relates to but does not explicitly use absolute ages in naming depositional sequences of varying frequencies. A chronostratigraphic system for naming stratigraphic units from parasequence to supersequence set level has been applied to Phanerozoic rocks from non-marine to deep-marine, siliciclastics and carbonates, high to low paleo latitude settings. Applications in the Gulf of Mexico Basin Cenozoic sediments demonstrate the utility, flexibility and impact of this system. Future revision of absolute ages in geologic time scales is easily accommodated in this stage-based designation system.

The system facilitates basinal, regional, or local scale stratigraphic comparisons, reduces uncertainty in paleogeographic mapping, and supports correlation of outcrop sections. This uniform designation scheme will also improve communication within a company and between institutions, as well as among academic investigators.

We do not attempt to establish the global synchrony of depositional sequences, nor do we advocate eustasy as the only driving mechanism for stratigraphic cyclicity. Nevertheless, a robust CDS underpins studies investigating synchrony of depositional sequences and differentiating relative sea level change as our biostratigraphic and geochronologic resolution continues to improve.