Correspondence of terrestrial and marine paleoclimates, SW Florida, during Mid-Pliocene periods of global warmth

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5808685

Willard, D A; Cronin, T M; Litwin, R J ^[1]

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1. Geological Survey, Reston, VA (United States) National Center

Pollen and ostracode samples from shallow-marine strata of the Pinecrest Beds near Sarasota, FL were studied to compare terrestrial and marine paleoclimate records during periods of middle Pliocene global warmth. Pollen assemblages from strata deposited during sea-level highstands from about 3.5--3.0 Ma are dominated by Pinus pollen with subdominant Ouercus and common taxodiaceous pollen, which increases markedly in abundance near about 3.0 Ma. Comparison with modern, shallow-marine pollen assemblages from the east coast of the United States indicates that the 3.5--3.0 Ma vegetation was, overall, similar to vegetation from the southern third Florida. However, near 3.0 Ma, pollen assemblages become less similar to modern assemblages due to higher percentages of taxodiaceous pollen and lower percentages of herbaceous pollen. Such changes are consistent with warmer climates and, possibly, moister soil conditions. Marine ostracodes also show progressively higher percentages of thermophilic (subtropical/tropical) taxa and decreasing percentages of cryophilic (temperature) taxa between 3.5--3.0 Ma. From about 2.5--2.0 Ma, ostracode assemblages recorded open-bay, sometimes brackish environments similar to those in subtropical eastern North America today. The Pinecrest paleoclimate record shows (1) that during two periods of global warmth and high sea level, subtropical terrestrial and marine climates were not substantially warmer than today; (2) ocean and atmosphere temperatures probably were about the same as today, perhaps slightly higher during peak warmth near 3.0 Ma; (3) changes in pollen assemblages appear to lag behind changes in ostracode assemblages; (4) progressively warmer local climates 3.5--3.0 Ma probably record an increasing influence of warm Gulf Stream water as the Central American Isthmus closed.

• OSTI ID: 5808685
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CENOZOIC ERA
CLIMATIC CHANGE
COMPARATIVE EVALUATIONS
DEVELOPED COUNTRIES
EVALUATION
FLORIDA
FLUCTUATIONS
FOSSILS
GAMETES
GEOLOGIC AGES
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GERM CELLS
LEVELS
NORTH AMERICA
OFFSHORE SITES
ONSHORE SITES
PALEOCLIMATOLOGY
PALEONTOLOGY
PALEOTEMPERATURE
PLIOCENE EPOCH
POLLEN
SEA LEVEL
TERTIARY PERIOD
USA
VARIATIONS