1. Diffuse spectral reflectance as a proxy for percent carbonate content in North Atlantic sediments
- Author
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Joseph D. Ortiz, Alan C. Mix, Suzanne O'Connell, and Sara E. Harris
- Subjects
geography ,Atlantic hurricane ,Milankovitch cycles ,geography.geographical_feature_category ,Climate oscillation ,Northern Hemisphere ,Paleontology ,Oceanography ,chemistry.chemical_compound ,Atlantic Equatorial mode ,chemistry ,Carbonate ,Glacial period ,Ice sheet ,Geology - Abstract
Diffuse reflectance records from Fern Drift in the North Atlantic faithfully record sediment percent carbonate. A high-resolu- tion, reflectance-based age model for these sediments derived from an orbitally tuned age model for western equatorial Atlantic, Ceara Rise sediments was generated by spectral frequency mapping. Power spectra of the Fern Drift record indicate statistically significant sub- Milankovitch cyclicity at 7.6-8.4 and 4.8-6.1 kyr. We infer that these -8 and -5 kyr cycles document a linkage between North and equa- torial Atlantic climate given our ability to correlate these records. These climate cycles influence Atlantic basin carbonate prior to the intensification of Northern Hemisphere glaciation and thus must arise from some portion of the climate system other than the dynamics of large ice sheets. The presence of these peaks, which could be related to equatorial clipped precession, implies a possible non-linear response to Milankovitch forcing. Abstract. Diffuse reflectance records from Feni Drift in the North Atlantic faithfully record sediment percent carbonate. A high-resolu- tion, reflectance-based age model for these sediments derived from an orbitally tuned age model for western equatorial Atlantic, Ceara Rise sediments was generated by spectral frequency mapping. Power spectra of the Feni Drift record indicate statistically significant sub- Milankovitch cyclicity at 7.6-8.4 and 4.8-6.1 kyr. We infer that these -8 and-5 kyr cycles document a linkage between North and equa- torial Atlantic climate given our ability to correlate these records. These climate cycles influence Atlantic basin carbonate prior to the intensification of Northern Hemisphere glaciation and thus must arise from some portion of the climate system other than the dynamics of large ice sheets. The presence of these peaks, which could be related to equatorial clipped precession, implies a possible non-linear response to Milankovitch forcing.
- Published
- 1999
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