Articles | Volume 31, issue 2
01 Jul 2012
 | 01 Jul 2012

Carbonate budget mass estimates for Neogene discoasters from the Equatorial Atlantic (Ceara Rise: ODP Site 927)

Inga Preiss-Daimler, Karl-Heinz Baumann, and Rüdiger Henrich

Keywords: Discoaster, Sphenolithus, carbonate budget, Neogene, Atlantic, shape factors

Abstract. Mass estimates for Late Miocene and Pliocene (8.6–3.25 Ma) Discoaster species and Sphenolithus are determined using samples of the equatorial Atlantic (Ceara Rise: ODP Site 927). Based on morphometric measurements, 3D computer models were created for 11 Discoaster species and their volumes calculated. From these, shape factors (ks) were derived to allow calculation of mass for different-sized discoasters and Sphenolithus abies. The mass estimates were then used to calculate the contribution of nannofossils to the total nannofossil carbonate. The discoaster contribution ranges from 10% to 40%, with a decreasing trend through the investigated interval. However, our estimates of total nannofossil carbonate from size-corrected abundance data are consistently 30–50% lower than estimates from grain-size measurement; this suggests that data based on mass estimates need to be interpreted with caution.