Freshwater input, upwelling, and the evolution of Caribbean coastal ecosystems during formation of the Isthmus of Panama

Online Access: Get full text
doi: 10.1130/G46357.1
Author(s): Grossman, Ethan L.; Robbins, John A.; Rachello-Dolmen, Paola G.; Tao, Kai; Saxena, Divya; O'Dea, Aaron
Author Affiliation(s): Primary:
Texas A&M University, Department of Geology and Geophysics, College Station, TX, United States
Other:
Smithsonian Tropical Research Institute, Panama
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 47(9), p.857-861. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. 35 refs.; illus., incl. sketch map
Summary: Caribbean biota underwent major ecological and evolutionary transformation in the Pliocene-Pleistocene, but a lack of detailed paleoenvironmental reconstruction prevents thorough resolution of cause and effect. We quantify levels of upwelling and freshwater input into Caribbean coastal shelf ecosystems over the last ∼6 m.y. with >3300 stable isotope measurements from 74 fossil serially sampled gastropods by normalizing δ18O values to open-ocean ∼18O from planktonic foraminifera. We find that the influence of Pacific-like upwelling in the southwestern Caribbean was low after 4.25 Ma but coastal ecosystems were heavily influenced by seasonal freshening until ca. 2.5 Ma, after which time low-freshwater conditions were established. The origination of modern oligotrophic coastal conditions was therefore a result of oceanographic change causing declining upwelling, and declining nutrients from terrestrial sources. We speculate that a southward shift of the Intertropical Convergence Zone, associated with Northern Hemisphere glaciation, reduced rainfall and terrestrial nutrient input and contributed to biotic turnover in the southwestern Caribbean, including the proliferation of modern reef communities.
Year of Publication: 2019
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Caribbean Sea; Cenozoic; Central America; Chemostratigraphy; Colombian Basin; DSDP Site 502; Deep Sea Drilling Project; East Pacific; Equatorial Pacific; Foraminifera; Fresh water; Gastropoda; IPOD; Isotope ratios; Isotopes; Isthmus of Panama; Leg 111; Leg 165; Leg 68; Microfossils; Mollusca; Neogene; North Atlantic; North Pacific; Northeast Pacific; O-18/O-16; ODP Site 677; ODP Site 999; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleo-oceanography; Paleocirculation; Paleoecology; Paleogeography; Panama; Pleistocene; Pliocene; Quaternary; Runoff; Sea water; Shells; Stable isotopes; Tertiary; Upwelling
Coordinates: N070000 N100000 W0780000 W0830000
Record ID: 2019065642
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States, Reference includes data supplied by the Geological Society of America