Ocean overturning since the Late Cretaceous: Inferences from a new benthic foraminiferal isotope compilation

• Published in: Paleoceanography and paleoclimatology Vol. 24; no. 42
• Main Authors: Cramer, B S, Toggweiler, J R, Wright, J D, Katz, M E, Miller, K G
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01.12.2009
• Subjects: Climate change; Cretaceous; Drilling; Earth; Eocene; Geobiology; Geophysics; Heterogeneity; Marine geology; Neogene; Ocean basins; Ocean circulation; Oceanography; Oceans; Oligocene; Paleoclimate science; Paleogene; Paleontology; Physical oceanography; Upwelling; Water circulation; Wind
• ISSN: 2572-4517; 2572-4525
• DOI: 10.1029/2008PA001683

Benthic foraminiferal oxygen isotopic ( 18 O) and carbon isotopic ( 13 C) trends, constructed from compilations of data series from multiple ocean sites, provide one of the primary means of reconstructing changes in the ocean interior. These records are also widely used as a general climate indicator for comparison with local and more specific marine and terrestrial climate proxy records. We present new benthic foraminiferal 18 O and 13 C compilations for individual ocean basins that provide a robust estimate of benthic foraminiferal stable isotopic variations to ~80 Ma and tentatively to ~110 Ma. First-order variations in interbasinal isotopic gradients delineate transitions from interior ocean heterogeneity during the Late Cretaceous (>~65 Ma) to early Paleogene (3565 Ma) homogeneity and a return to heterogeneity in the late Paleogeneearly Neogene (350 Ma). We propose that these transitions reflect alterations in a first-order characteristic of ocean circulation: the ability of winds to make water in the deep ocean circulate. We document the initiation of large interbasinal 18 O gradients in the early Oligocene and link the variations in interbasinal 18 O gradients from the middle Eocene to Oligocene with the increasing influence of wind-driven mixing due to the gradual tectonic opening of Southern Ocean passages and initiation and strengthening of the Antarctic Circumpolar Current. The role of wind-driven upwelling, possibly associated with a Tethyan Circumequatorial Current, in controlling Late Cretaceous interior ocean heterogeneity should be the subject of further research.