Influence of increasing carbonate saturation in Atlantic bottom water during the late Miocene

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doi: 10.1016/j.palaeo.2019.01.006
Author(s): Keating-Bitonti, Caitlin R.; Peters, Shanan E.
Author Affiliation(s): Primary:
University of Wisconsin at Madison, Department of Geoscience, Madison, WI, United States
Volume Title: Palaeogeography, Palaeoclimatology, Palaeoecology
Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Vol.518, p.134-142. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0031-0182 CODEN: PPPYAB
Note: In English. 97 refs.; illus., incl. 2 tables, sketch map
Summary: The late Miocene witnessed the tectonic uplift of the Isthmus of Panama, the onset of modern-like thermohaline circulation, changes in global patterns of deep-sea sedimentation, and a negative shift of 1 ppm in the carbon isotopic composition (δ13C) of marine carbonate sediments. Although previous work has attributed the late Miocene carbon isotopic shift (LMCS) to biological and environmental factors, the reasons for this apparent shift in the global carbon cycle remain incompletely understood. Here we combine both core-based sedimentological and isotopic data from three Walvis Ridge sites in the southeastern Atlantic Ocean with macrostratigraphic data from the entire Atlantic basin to show that the LMCS marks the establishment of modern, glacial/interglacial seawater carbonate saturation levels in the Atlantic. Between 10 and 7 million years ago (Ma) the Atlantic Ocean shows a trend of increasing seafloor area preserving deep-sea carbonate sediments. Neogene carbonate sedimentation in the Atlantic Ocean peaked at 7 Ma, coinciding with a δ13C shift of approximately -0.8 ppm in Walvis Ridge benthic foraminifera, similar to the magnitude of LMCS. Northern-sourced waters in the late Miocene likely shifted seawater carbonate chemistry throughout the Atlantic basin by introducing bottom waters with higher carbonate ion concentrations. LMCS reflects the introduction of a carbonate ion effect on North Atlantic Deep Water (NADW) by increasing Northern Hemisphere glacial carbonate weathering. A carbonate ion flux to the Labrador Seawater contribution of NADW raises the possibility of a carbonate burial-mediated feedback with the global climate system that led to additional cooling during the Miocene-Pliocene transition.
Year of Publication: 2019
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Arctic Ocean; Atlantic Bottom Water; Atlantic Ocean; Bottom water; C-13/C-12; Calcium carbonate; Carbon; Carbon cycle; Carbon dioxide; Carbonate ion; Carbonate sediments; Cenozoic; Chordata; Deep Sea Drilling Project; Fish; Foraminifera; Geochemical cycle; Isotope ratios; Isotopes; Leg 208; Marine environment; Marine sediments; Microfossils; Miocene; Neogene; North Atlantic; North Atlantic Deep Water; Northern Hemisphere; Norwegian Sea; ODP Site 1262; ODP Site 1264; ODP Site 1266; Ocean Drilling Program; Paleo-oceanography; Preservation; Saturation; Sediments; South Atlantic; Stable isotopes; Teeth; Tertiary; Thermohaline circulation; Upper Miocene; Vertebrata; Walvis Ridge
Coordinates: S283300 S283200 E0022100 E0022000
S283200 S283200 E0025100 E0025100
S271100 S271100 E0013500 E0013400
Record ID: 2019040479
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands