Late Cretaceous and early Paleogene nutrient and paleoproductivity records from Blake Nose, western North Atlantic Ocean

Abstract

[1] We evaluate phosphorus (P) and biogenic barium (bio-Ba) as nutrient burial and export productivity indicators for the Late Cretaceous and early Paleogene, combining these with calcium carbonate (CaCO 3 ), organic carbon (C), and bulk CaCO 3 C isotopes (d 13 C). Sample ages span 36-71 Ma ($1 sample/0.5 m.y.) for a depth transect of sites in the western North Atlantic (Blake Nose, Ocean Drilling Program Leg 171B, Sites 1052, 1051, and 1050). We use a multitracer approach including redox conditions to investigate export productivity surrounding the global Paleocene d 13 C maximum ($57 Ma). Reducing conditions render most of the bio-Ba record not useful for export productivity interpretations. P and organic C records indicate that regional nutrient and organic C burial were high at $61 and $69 Ma, and low during the Paleocene d 13C maximum, a time of proposed global high relative organic C burial. Observed organic C burial changes at Blake Nose cannot explain this C isotope excursion.

Opal-associated particulate phosphorus: Implications for the marine P cycle

“…Because CFA is relatively stable in ocean sediments, this systematic redistribution of P in sediments or ''sink-switching'' results in CFA being a long term net sink for P from the oceans (Filippelli and Delaney, 1996;Faul et al, 2003). The conversion of more labile forms of P (organic and oxide-associated) to authigenic P is time dependent (Filippelli and Delaney, 1996;Faul et al, 2003), therefore, the conversion is likely ongoing in young sediments. Because of this reorganization of P within sediments, to evaluate organic P burial and the relationships with export production and nutrient utilization, total reactive P concentrations (the sum of the P that is adsorbed or associated with oxides, authigenic P, and the remaining organic P in a sample) and accumulation rates need to be determined .…”

“…As a result of this diagenetic reorganization of P within sediments, organic P concentrations usually decrease with time as it is ultimately transformed to authigenic P during diagenesis (Ruttenberg and Berner, 1993;Filippelli and Delaney, 1996;Delaney and Anderson, 1997;Anderson et al, 2001). Because CFA is relatively stable in ocean sediments, this systematic redistribution of P in sediments or ''sink-switching'' results in CFA being a long term net sink for P from the oceans (Filippelli and Delaney, 1996;Faul et al, 2003). The conversion of more labile forms of P (organic and oxide-associated) to authigenic P is time dependent (Filippelli and Delaney, 1996;Faul et al, 2003), therefore, the conversion is likely ongoing in young sediments.…”

“…Sequential extraction techniques have been utilized to try to understand the diagenetic transformations of organic P in sediments, usually using some variation of the SEDEX reaction scheme (Ruttenberg and Berner, 1993;Filippelli and Delaney, 1996;Slomp et al, 1998;Anderson and Delaney, 2000;Latimer and Filippelli, 2001;Slomp et al, 2002;Tamburini et al, 2002;van der Zee et al, 2002;Faul et al, FilippelliI et al, 2003). During diagenesis, organic P is released to pore waters where it can undergo several different chemical or physical processes including becoming associated with Fe and Mn oxides or oxyhydroxides, adsorbed to mineral surfaces, refluxed to the overlying bottom water, or converted to an authigenic mineral phase such as carbonate fluorapatite (CFA) (Ruttenberg, 1992).…”

Coordinated shifts to non-planktotrophic development in spatangoid echinoids during the Late Cretaceous

“…Sea surface temperature was falling rapidly (e.g. Gale 2000) and, while total primary productivity was increasing (Faul et al 2003), there is evidence that this was associated with increasing climatic seasonality (Steuber 1996;Francis & Poole 2002;Steuber et al 2005;Dutton et al 2007) and vigorous seasonal upwelling (Handoh et al 2003). These changes would have led to the nutrient supply available to planktotrophic larvae becoming more abundant yet less reliable.…”

Data Report: Carbonate and Barite Trends across the Eocene/Oligocene Boundary at Shatsky Rise, ODP Leg 198

“…However, the multiple processes that influence these properties, including changes in ocean circulation, dissolution, diagenesis, and nutrient availability, complicate interpretations of these proxies. For example, although the carbonate flux in sediment traps show a good correlation with organic carbon flux under certain conditions in the open ocean above the lysocline (Deuser et al, 1981;Ruhlemann et al, 1996) One of the most widely used paleoproductivity proxies is excess Ba accumulation in sediments (defined as the Ba not associated with terrigenous matter) (as in Bains et al, 2000;Bonn et al, 1998;Dymond et al, 1992;Faul et al, 2003;Francois et al, 1995;Klump et al, 2001;Nilsen et al, 2003;Nurnberg et al, 1997;Pfeifer et al, 2001). This application is based on the strong relationship between excess Ba and organic carbon fluxes observed in sediment traps (Dymond et al, 1992;Francois et al, 1995) and the high excess Ba or barite accumulation rate in sediment underlying areas of high productivity (Eagle et al, 2003;Gingele and Dahmke, 1994;Goldberg et al, 1969;Revelle, 1955).…”