publication . Article . 2018

Astronomical tunings of the Oligocene–Miocene transition from Pacific Ocean Site U1334 and implications for the carbon cycle

Beddow, Helen M.; Liebrand, Diederik; Wilson, Douglas S.; Hilgen, Frits J.; Sluijs, Appy; Wade, Bridget S.; Lourens, Lucas J.; Stratigraphy and paleontology; Marine palynology and palaeoceanography; Stratigraphy & paleontology;
Open Access
  • Published: 05 Mar 2018 Journal: Climate of the Past, volume 14, pages 255-270 (eissn: 1814-9332, Copyright policy)
  • Publisher: Copernicus GmbH
  • Country: Netherlands
Abstract
Astronomical tuning of sediment sequences requires both unambiguous cycle pattern recognition in climate proxy records and astronomical solutions, as well as independent information about the phase relationship between these two. Here we present two different astronomically tuned age models for the Oligocene–Miocene transition (OMT) from Integrated Ocean Drilling Program Site U1334 (equatorial Pacific Ocean) to assess the effect tuning has on astronomically calibrated ages and the geologic timescale. These alternative age models (roughly from ∼ 22 to ∼ 24 Ma) are based on different tunings between proxy records and eccentricity: the first age model is based on an aligning CaCO3 weight (wt%) to Earth's orbital eccentricity, and the second age model is based on a direct age calibration of benthic foraminiferal stable carbon isotope ratios (δ13C) to eccentricity. To independently test which tuned age model and associated tuning assumptions are in best agreement with independent ages based on tectonic plate-pair spreading rates, we assign the tuned ages to magnetostratigraphic reversals identified in deep-marine magnetic anomaly profiles. Subsequently, we compute tectonic plate-pair spreading rates based on the tuned ages. The resultant alternative spreading-rate histories indicate that the CaCO3 tuned age model is most consistent with a conservative assumption of constant, or linearly changing, spreading rates. The CaCO3 tuned age model thus provides robust ages and durations for polarity chrons C6Bn.1n–C7n.1r, which are not based on astronomical tuning in the latest iteration of the geologic timescale. Furthermore, it provides independent evidence that the relatively large (several 10 000 years) time lags documented in the benthic foraminiferal isotope records relative to orbital eccentricity constitute a real feature of the Oligocene–Miocene climate system and carbon cycle. The age constraints from Site U1334 thus indicate that the delayed responses of the Oligocene–Miocene climate–cryosphere system and (marine) carbon cycle resulted from highly non-linear feedbacks to astronomical forcing.
Persistent Identifiers
Fields of Science and Technology classification (FOS)
01 natural sciences, 0105 earth and related environmental sciences, 010502 geochemistry & geophysics, 010504 meteorology & atmospheric sciences
Sustainable Development Goals (SDG)
13. Climate action
Subjects
arXiv: Physics::Geophysics
free text keywords: Paleontology, Stratigraphy, Global and Planetary Change, Palaeontology, Tectonics, Orbital eccentricity, Polarity chron, Global and Planetary Change, Isotopes of carbon, Carbon cycle, Paleontology, Magnetic anomaly, Geologic time scale, Geology, lcsh:Environmental pollution, lcsh:TD172-193.5, lcsh:Environmental protection, lcsh:TD169-171.8, lcsh:Environmental sciences, lcsh:GE1-350
Communities
  • Digital Humanities and Cultural Heritage
Funded by
NWO| Evolution of astronomically paced climate changes from Greenhouse to Icehouse world
Project
  • Funder: Netherlands Organisation for Scientific Research (NWO) (NWO)
  • Project Code: 2300157723
,
EC| ERAS
Project
ERAS
Enhanced Research Activities in Stratigraphy
  • Funder: European Commission (EC)
  • Project Code: 293741
  • Funding stream: FP7 | SP3 | PEOPLE
,
EC| EARTHSEQUENCING
Project
EARTHSEQUENCING
A new approach to sequence Earth history at high resolution over the past 66 million years
  • Funder: European Commission (EC)
  • Project Code: 617462
  • Funding stream: FP7 | SP2 | ERC
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