Biogeography of terminal Cretaceous benthic foraminifera: deep-water circulation and trophic gradients in the deep South Atlantic

The biogeographic distribution of terminal Cretaceous (late Maastrichtian) deep-sea benthic foraminifera are analysed from the South Atlantic Ocean. The data quantified derive from six DSDP sites representing a west-to-east transect in mid-latitudes and three high-latitude ODP sites. Correspondence analysis revealed five benthic foraminiferal assemblages that are representative of bathymetrically and latitudinally different environmental settings within the South Atlantic: (1) a Shallow Mid-Latitude Assemblage [Bolivinoides draco, Eouvigerina subsculptura, Gaudryina pyramidata, Scheibnerova? sp., Spiroplectammina spp. (calcerous forms) and Tritaxia aspera]; (2) an Intermediate Mid-Latitude Assemblage [Cibicidoides hyphalus, Nuttallides truempyi, Paralabamina lunata, Praebulimina spp., Sitella cushmani and Valvalabamina sp. (involute form)]; (3) a Deep Mid-Latitude Assemblage (Bulimina velascoensis, Gyroidinoides beisseli, Nuttallinella sp. A. Oridorsalis-complex, Osangularia? sp., Paralabamina hillebrandti, Quadrimorphina camerata, Reussella szajnochae szajnochae and Sitella cf. plana); (4) a Shallow High-Latitude Assemblage (Alabamina creta, Brizalina incrassata, Osangularia texana, Pullenia coryelli, Pyramidina rudita and Spiroplectammina 'crassa'); and (5) a Deep High-Latitude Assemblage [Gavelinella beccariiformis, Gyroidinoides quadratus, Nuttallides sp. A, Osangularia velascoensis, Paralabamina sp. (intermediate form), Valvalabamina? praeacuta and Spiroplectammina dentata]. Comparison of the proportions of epibenthic/endobenthic morphotypes within each of the five assemblages resulting from correspondence analysis suggests clear trends between sites of the mid- and high latitudes respectively, and along bathymetric gradients among sites of similar latitudes. These trends are inferred to represent environmental (such as trophic and oxygenation) gradients when placed within a framework of hypothesized surface circulation and upwelling patterns in the late Maastrichtian South Atlantic. (C) 2000 Academic Press.