Astronomical calibration of the Ypresian timescale; implications for sea-floor spreading rates and the chaotic behavior of the solar system?

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doi: 10.5194/cp-13-1129-2017
Author(s): Westerhold, Thomas; Röhl, Ursula; Frederichs, Thomas; Agnini, Claudia; Raffi, Isabella; Zachos, James C.; Wilkens, Roy H.
Author Affiliation(s): Primary:
University of Bremen, MARUM-Center for Marine Environmental Sciences, Bremen, Germany
Universita degli Studi di Padova, Italy
Universita degli Studi "G. d'Annunzio" Chieti-Pescara, Italy
University of California at Santa Cruz, United States
University of Hawaii, United States
Volume Title: Climate of the Past
Source: Climate of the Past, 13(9), p.1129-1152. Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1814-9324
Note: In English. 88 refs.; illus., incl. 3 tables
Summary: To fully understand the global climate dynamics of the warm early Eocene with its reoccurring hyperthermal events, an accurate high-fidelity age model is required. The Ypresian stage (56-47.8 Ma) covers a key interval within the Eocene as it ranges from the warmest marine temperatures in the early Eocene to the long-term cooling trends in the middle Eocene. Despite the recent development of detailed marine isotope records spanning portions of the Ypresian stage, key records to establish a complete astronomically calibrated age model for the Ypresian are still missing. Here we present new high-resolution X-ray fluorescence (XRF) core scanning iron intensity, bulk stable isotope, calcareous nannofossil, and magnetostratigraphic data generated on core material from ODP Sites 1258 (Leg 207, Demerara Rise), 1262, 1263, 1265, and 1267 (Leg 208, Walvis Ridge) recovered in the equatorial and South Atlantic Ocean. By combining new data with published records, a 405 kyr eccentricity cyclostratigraphic framework was established, revealing a 300-400 kyr long condensed interval for magnetochron C22n in the Leg 208 succession. Because the amplitudes are dominated by eccentricity, the XRF data help to identify the most suitable orbital solution for astronomical tuning of the Ypresian. Our new records fit best with the La2010b numerical solution for eccentricity, which was used as a target curve for compiling the Ypresian astronomical timescale (YATS). The consistent positions of the very long eccentricity minima in the geological data and the La2010b solution suggest that the macroscopic feature displaying the chaotic diffusion of the planetary orbits, the transition from libration to circulation in the combination of angles in the precession motion of the orbits of Earth and Mars, occurred ∼ 52 Ma. This adds to the geological evidence for the chaotic behavior of the solar system. Additionally, the new astrochronology and revised magnetostratigraphy provide robust ages and durations for Chrons C21n to C24n (47-54 Ma), revealing a major change in spreading rates in the interval from 51.0 to 52.5 Ma. This major change in spreading rates is synchronous with a global reorganization of the plate-mantle system and the chaotic diffusion of the planetary orbits. The newly provided YATS also includes new absolute ages for biostratigraphic events, magnetic polarity reversals, and early Eocene hyperthermal events. Our new bio- and magnetostratigraphically calibrated stable isotope compilation may act as a reference for further paleoclimate studies of the Ypresian, which is of special interest because of the outgoing warming and increasingly cooling phase. Finally, our approach of integrating the complex comprehensive data sets unearths some challenges and uncertainties but also validates the high potential of chemostratigraphy, magnetostratigraphy, and biostratigraphy in unprecedented detail being most significant for an accurate chronostratigraphy.
Year of Publication: 2017
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; 18 Geophysics, Solid-Earth; Atlantic Ocean; Biostratigraphy; Calibration; Cenozoic; Chaotic behavior; Chemostratigraphy; Chron C22n; Chronostratigraphy; Climate change; Climate forcing; Cores; Correlation; Cosmochronology; Cyclic processes; Cyclostratigraphy; Demerara Rise; Distortion; Eccentricity; Eocene; Equatorial Atlantic; Global change; Global warming; Imagery; Isotopes; Leg 207; Leg 208; Lower Eocene; Magnetostratigraphy; Microfossils; Nannofossils; North Atlantic; Northwest Atlantic; ODP Site 1258; ODP Site 1262; ODP Site 1263; ODP Site 1265; ODP Site 1267; Ocean Drilling Program; Ocean floors; Orbital forcing; Paleocene-Eocene Thermal Maximum; Paleoclimatology; Paleogene; Paleomagnetism; Precession; Rates; Sea-floor spreading; Solar system; South Atlantic; Spectra; Stable isotopes; Statistical analysis; Stratigraphic boundary; Succession; Tertiary; Time scales; Variations; Walvis Ridge; West Atlantic; X-ray fluorescence spectra; Ypresian
Coordinates: N092600 N092600 W0544400 W0544400
S271100 S271100 E0013500 E0013400
S283200 S283200 E0024700 E0024700
S285000 S285000 E0023800 E0023800
S280600 S280600 E0014300 E0014200
Record ID: 2018003550
Copyright Information: GeoRef, Copyright 2020 American Geosciences Institute. Reference includes data from Copernicus Gesellschaft, Katlenburg-Lindau, Germany