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The fertilization of the Bahamas by Saharan dust; a trigger for carbonate precipitation?

P. K. Swart, A. M. Oehlert, G. J. Mackenzie, Gregor P. Eberli and J. J. G. Reijmer
The fertilization of the Bahamas by Saharan dust; a trigger for carbonate precipitation?
Geology (Boulder) (June 2014) 42 (8): 671-674

Abstract

The enigma of the Bahamas is that this highly productive carbonate system has existed for at least 100 m.y., building a vast edifice of carbonates, thousands of meters thick, in an essentially nutrient-poor environment. Based on measurements of the insoluble material, the Fe and Mn in the carbonate fraction, and the delta (super 15) N of the sedimentary organic matter, we suggest a paradigm shift in order to explain the formation of the Bahamas and possibly other similar platforms. We propose that the Great Bahama Bank is currently, and may in the past have been, fertilized by atmospheric dust, promoting the fixation of atmospheric N (sub 2) by cyanobacteria. These cyanobacteria provided a source of nitrogen to the rest of the community in this nutrient-poor environment. The fixation of N has imparted a characteristic delta (super 15) N signal and has been responsible, through the drawdown of CO (sub 2) , for initiating the precipitation of carbonate in the shallow waters. This phenomenon might be responsible for the formation of vast amounts of sediments in the oceans, not only within recent times, but throughout geological history, particularly in the early history of the Earth prior to the existence of calcium carbonate-secreting organisms.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 42
Serial Issue: 8
Title: The fertilization of the Bahamas by Saharan dust; a trigger for carbonate precipitation?
Affiliation: University of Miami, Rosenstiel School of Marine and Atmospheric Sciences, Miami, FL, United States
Pages: 671-674
Published: 20140630
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 38
Accession Number: 2014-058225
Categories: OceanographyGeneral geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2014251
Illustration Description: illus. incl. 1 table
N22°00'00" - N26°00'00", W79°19'60" - W76°00'00"
Secondary Affiliation: Vrije Universiteit Amsterdam, NLD, Netherlands
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201431
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