Characterization of coccolithophore assemblages in the offshore basins of the Colombian Pacific
DOI:
https://doi.org/10.25268/bimc.invemar.2019.48.2.768.Keywords:
Coccolithophores, Colombian Pacific, Chocó basin, Tumaco basin, QuaternaryAbstract
This study was conducted on coccolithophores recovered from 39 piston-core samples taken offshore Chocó and Tumaco basins, on the Colombian Pacific. Qualitative and quantitative analyses of the coccoliths showed changes in the relative abundances and the state of preservation in the two basins. The examined sediments were characterized by the coccoliths Gephyrocapsa oceanica, Gephyrocapsa
muellerae, Gephyrocapsa <3 μm, Emiliania huxleyi, Calcidiscus leptoporus and Helicosphaera carteri, which presented abundances higher than 2 %. We also identified a minority assemblage (<2%) constituted by Ceratolithus spp., Coccolithus pelagicus, Florisphaera profunda,
Helicosphaera princei, Helicosphaera sellii, Helicosphaera wallichii and Pontosphaera spp. together with reworked specimens of Reticulofenestra spp, Sphenolithus spp. and Discoaster spp. The recovery of E. huxleyi as part of the assemblage indicates that the studied sediments are younger than the biozone NN21, covering an age range of Middle Pleistocene (Ionian). The number of coccoliths per gram (cc/g) was calculated, demonstrating an average of 5.7x106 cc/g and 1.2x107 cc/g for Chocó and Tumaco basins, respectively. In order to interpret the causes of this variance, we performed a multivariate redundancy analysis (RDA), showing that the distance to the coastline is the controlling factor of the fluctuations of the relative abundances and distribution of the coccoliths in both basins.
References
Bedoya, E. L., Flores, J. A., Pardo, A. (2013). Nanofósiles calcáreos y bioestratigrafía del Mioceno Tardío del SW de la Cuenca Tumaco onshore (Pacífico Colombiano). Boletín de Geología UIS, 35(1): 55-66.
Betancur, M. J., y Martínez, I. (2003). Foraminíferos bentónicos recientes en sedimentos de fondo de la Cuenca de Panamá (Pacífico Colombiano), como indicadores de productividad y oxigenación. Boletin Investigación Marina Costera, 32: 92-123.
Flores, J.A., Sierro, F.J. (2007). Paleoceanography, biological proxies Coccoliths, Elsevier, Oxford, p. 1634-1646.
Flores, J. A. Sierro, F. J. (1997). Revised technique for calculation of calcareous nannofossil accumulation rates. Micropaleontology, 43: 321-324.
Gómez, C., Martinez, I. (2005). Nueva productividad biológica en el Pacífico oriental ecuatorial: respuesta al aporte de nutrientes por los ríos del Pacífico colombiano, surgencia costera y polvo atmosférico. Boletín de Geología, 27 (2): 100-114.
Patarroyo, G. D., Martínez, J. I. (2013). Foraminíferos bentónicos recientes en las aguas profundas de la Cuenca de Panamá: ecología y su posible relación con las corrientes de fondo. Boletín de Investigaciones Marinas y Costeras, 42 (1): 31-55.
Patarroyo, G. D., Martínez, J. I. (2016). Paleoxigenación y paleoproductividad en el Golfo de Panamá durante el Holoceno tardío. Boletín de geología, 38 (2): 75-92.
Saavedra-Pellitero, M., Flores, J. A., Baumann, K. H., Sierro, F. J. (2010). Coccolith distribution patterns in surface sediments of Equatorial and Southeastern Pacific Ocean. Geobios, 43 (1): 131-149.
Saavedra-Pellitero, M., Flores, J.A., Lamy, F., Sierro, F.J., Cortina, A. (2011). Coccolithophore estimates of paleotemperature and paleoproductivity changes in the southeast Pacific over the past∼ 27 kyr. Paleoceanography, 26: 1-16.
Young, J. R., Geisen, M., Cros, L., Kleijne, A., Sprengel, C., Probert, I., y Østergaard, J. (2003). A guide to extant coccolithophore taxonomy. Journal of Nannoplankton Research, p. 125.
