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Secular variations in the carbonate chemistry of the oceans over the Cenozoic
- Source :
- Earth and Planetary Science Letters, 512, 194. Elsevier, Earth and Planetary Science Letters, 512 . pp. 194-206.
- Publication Year :
- 2019
-
Abstract
- Oceanic carbonate chemistry during the Cenozoic has affected the climatology, ecology, and marine geology of our planet; yet, we have limited means to know the evolution of that chemistry, due to a lack of preserved and unaltered seawater samples and a continuing paucity of proxies. Modeling is often used to address this problem; here, we offer a simple, data-driven, secular timescale, inverse model for the mean, Cenozoic, carbonate chemistry of the oceans. Inputs for the model include carbonate compensation depth (CCD), CaCO3 burial, seawater temperature, atmospheric CO2 and carbonate ion records, as well as a simple set of original, but justified, assumptions. The model retrodicts the total dissolved inorganic carbon (DIC), carbonate alkalinity (CAlk), and pH of the surface and deep waters of the ocean. The retrodicted DIC and CAlk records do not indicate any unusually elevated values in the early Cenozoic, as found in some past studies. If the CCD record from Lyle et al. (2008) is employed, the changes in DIC and CAlk appear entirely related to changes in the alkalinity input to the pelagic oceans and atmospheric CO2; however, with the CCD from Palike et al. (2012) , the increases in DIC and CAlk during the last 15 Ma reflect the effects of ocean cooling. Using either CCD-record, our model provides consistent retrodictions of the available pH record. Our results are not consistent with many past modeling assumptions, such as constancy of alkalinity in surface waters, or the ratio of shallow and deep carbonate ion concentrations. Finally, we use our results to provide new estimates of atmospheric CO2 based on Boron isotopes and find significantly lower CO2 values in the early Cenozoic than previous values.
- Subjects :
- seawater ph record
010504 meteorology & atmospheric sciences
Marine geology
Geochemistry
Alkalinity
010502 geochemistry & geophysics
01 natural sciences
chemistry.chemical_compound
Geochemistry and Petrology
Dissolved organic carbon
Taverne
Earth and Planetary Sciences (miscellaneous)
14. Life underwater
0105 earth and related environmental sciences
cenozoic era
carbonate chemistry
inverse model
Geophysics
chemistry
13. Climate action
Space and Planetary Science
atmospheric pCO2 record
Carbonate Ion
Carbonate
Seawater
Cenozoic
Geology
Carbonate compensation depth
Subjects
Details
- Language :
- English
- ISSN :
- 0012821X
- Database :
- OpenAIRE
- Journal :
- Earth and Planetary Science Letters, 512, 194. Elsevier, Earth and Planetary Science Letters, 512 . pp. 194-206.
- Accession number :
- edsair.doi.dedup.....292cffb9dd6df933ac1617bccb63f3e4