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Organic carbon flux and organic carbon to calcite flux ratio recorded in deep‐sea carbonates: Demonstration and a new proxy
Author(s) -
Mekik Figen A.,
Loubere Paul W.,
Archer David E.
Publication year - 2002
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2001gb001634
Subject(s) - calcite , carbonate , geology , total organic carbon , flux (metallurgy) , calcareous , seabed , mineralogy , sediment , oceanography , calcium carbonate , deep sea , geochemistry , environmental chemistry , geomorphology , paleontology , chemistry , organic chemistry
Theoretical considerations indicate that degree of bottom water calcite saturation, organic carbon flux, and the ratio of that flux to the calcite flux all are reflected in the carbonate preservation record of deep‐sea sediments. Separating the influence of these various factors on the record depends first on estimating the percent of the calcite flux which is dissolved at the seabed. We have developed a new proxy for percent dissolved calcite by calibrating a foraminiferal fragmentation index to biogeochemical model‐derived data. Application of our proxy, combined with geochemical modeling, to the surface sediments of the Eastern Equatorial Pacific [EEP], demonstrates the need for all three of the variables listed above to account for the observations. Further, we used reverse modeling to map the ratio of the biotic fluxes across the EEP. We observe a coherent regional pattern with highest ratio values, as expected, associated with areas of upwelling, particularly along South America. Our proxy appears to be unaffected by carbonate sediment properties such as percent calcite in samples or the amount of coarse fraction (>63 μm) in the calcareous portion of the sediments; therefore it reflects primarily the geochemical environment rather than characteristics of seabed deposits.