Revision of the Late Miocene, Pliocene and Pleistocene Sequence Cycles
W. W. Wornardt, Jr.1, B. Shaffer1, and P. R. Vail2
1Microstrat Inc., Houston
2Rice University, Houston, TX
Wornardt and Vail published their “Mio-Pleistocene sequence chronostratigraphic chart” for the Gulf of Mexico in an abstract in 1990. Berggren et al. (1995), included updated numerical ages for approximate 100 calcareous nannofossils and 150 planktonic foraminiferal LADs and FADs. The Pl-zonal scheme and the M-zonal scheme established by Berggren et al. (1995b) are shown on the left side of Figure 1.
Subsequently we have revised the late Miocene, Pliocene and Pleistocene Sequence Chronostratigraphy and incorporated the these latest revisions into our correlation of numerical age (Ma), chrons, polarity, epochs, relative age, planktonic foraminiferal zones, calcareous nannofossil zones, oxygen Isotope record, sequences and bioevents of Berggren 1995 and Hardenbol et 1998.
We divided the late Miocene, Pliocene and Pleistocene into a series of eleven (11) third order depositional sequences from 9.26 Ma to 0.8 Ma and seven (7) fourth order depositional sequences, from 0.7 to 0.1 Ma. The age of the third order sequence boundaries that we recognize are: 6.98, 5.73, 4.37, 3.95, 3.21, 2.76, 2.50, 2.09, 1.56, 1.40 and 0.80 Ma. Within each sequence, the third order maximum flooding surfaces that we recognize are: 7.65, 6.00, 5.20, 4.00, 3.58, 2.88, 2.59, 2.21, 1.59, 1.47 and 0.96 Ma. The fourth order maximum flooding surfaces that we recognize are: 0.76, 0.66, 0.56, 0.46, 0.36, 0.26, 0.16, and 0.06 Ma. The approximate age of the top slope fan in these sequences is 5.60, 3.90, 3.09, 2.30, 1.95 and 1.22, based on the highest occurrence of more cool water assemblage of species.
AAPG Search and Discovery Article #90901©2001 GCAGS, Annual Meeting, Shreveport, Louisiana