DOI: 10.1016/j.epsl.2018.01.003
Scopus记录号: 2-s2.0-85044782777
论文题名: Towards a robust and consistent middle Eocene astronomical timescale
作者: Boulila S. ; Vahlenkamp M. ; De Vleeschouwer D. ; Laskar J. ; Yamamoto Y. ; Pälike H. ; Kirtland Turner S. ; Sexton P.F. ; Westerhold T. ; Röhl U.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 486 起始页码: 94
结束页码: 107
语种: 英语
英文关键词: astronomical timescale
; Middle Eocene
; Newfoundland Ridge
; obliquity
; s3–s6 modulation cycle
Scopus关键词: Calibration
; Carbonation
; Clay deposits
; Geochronology
; Lithology
; Magnetism
; Modulation
; Orbits
; Middle Eocene
; Modulation cycles
; Newfoundlands
; obliquity
; Time-scales
; Magnetic polarity
; cyclicity
; dating method
; Eocene
; geochronology
; obliquity
; timescale
; Atlantic Ocean
; Atlantic Ocean (Equatorial)
; Canada
; Newfoundland
; Newfoundland and Labrador
英文摘要: Until now, the middle Eocene has remained a poorly constrained interval of efforts to produce an astrochronological timescale for the entire Cenozoic. This has given rise to a so-called “Eocene astronomical timescale gap” (Vandenberghe et al., 2012). A high-resolution astrochronological calibration for this interval has proven to be difficult to realize, mainly because carbonate-rich deep-marine sequences of this age are scarce. In this paper, we present records from middle Eocene carbonate-rich sequences from the North Atlantic Southeast Newfoundland Ridge (IODP Exp. 342, Sites U1408 and U1410), of which the cyclical sedimentary patterns allow for an orbital calibration of the geologic timescale between ∼38 and ∼48 Ma. These carbonate-rich cyclic sediments at Sites U1408 and U1410 were deposited as drift deposits and exhibit prominent lithological alternations (couplets) between greenish nannofossil-rich clay and white nannofossil ooze. The principal lithological couplet is driven by the obliquity of Earth's axial tilt, and the intensity of their expression is modulated by a cyclicity of about 173 kyr. This cyclicity corresponds to the interference of secular frequencies s3 and s6 (related to the precession of nodes of the Earth and Saturn, respectively). This 173-kyr obliquity amplitude modulation cycle is exceptionally well recorded in the XRF (X-ray fluorescence)-derived Ca/Fe ratio. In this work, we first demonstrate the stability of the (s3–s6) cycles using the latest astronomical solutions. Results show that this orbital component is stable back to at least 50 Ma, and can thus serve as a powerful geochronometer in the mid-Eocene portion of the Cenozoic timescale. We then exploit this potential by calibrating the geochronology of the recovered middle Eocene timescale between magnetic polarity Chrons C18n.1n and C21n. Comparison with previous timescales shows similarities, but also notable differences in durations of certain magnetic polarity chrons. We present a revision of previous astronomical timescales from the Equatorial and South Atlantic, to overcome the differences between different mid-Eocene astrochronologies. Using our new records from the North Atlantic, combined with existing records from the South Atlantic (ODP Site 1263 and Hole 702B) and Equatorial Atlantic (ODP Site 1260), we revise the durations of magnetic polarity Chrons C18n.1n to C21n, thereby arriving at a robust and self-consistent closure of the middle Eocene astronomical timescale gap. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110019
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Université Paris VI, CNRS – UMR 7193 ISTeP ‘Institut des Sciences de la Terre-Paris’, case 117, 4, place Jussieu, Paris cedex 05, 75252, France; ASD, IMCCE-CNRS UMR 8028, Observatoire de Paris, UPMC, 77 avenue Denfert-Rochereau, Paris, 75014, France; MARUM – Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse 8, Bremen, 28359, Germany; Center for Advanced Marine Core Research, Kochi University, B200 Monobe, Kochi, Nankoku 783-8502, Japan; Department of Earth Sciences, University of California, Riverside, CA 92521, United States; School of Environment, Earth and Ecosystem Sciences, The Open University, Walton Hall, Milton Keynes, Buckinghamshire MK7 6AA, United Kingdom
Recommended Citation:
Boulila S.,Vahlenkamp M.,De Vleeschouwer D.,et al. Towards a robust and consistent middle Eocene astronomical timescale[J]. Earth and Planetary Science Letters,2018-01-01,486