 |
| Titel |
Late Miocene climate and orbital time scale reconciliation from a deep-sea perspective |
| VerfasserIn |
Anna Joy Drury, Thomas Westerhold, Thomas Frederichs, Jun Tian, Roy Wilkens, James E. T. Channell, Helen Evans, Cédric M. John, Mitch Lyle, Ursula Röhl |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250143269
|
| Publikation (Nr.) |
 EGU/EGU2017-6975.pdf |
|
|
|
|
|
| Zusammenfassung |
| The late Tortonian to early Messinian (8-6 Ma) is characterised by a long-term reduction in
benthic foraminiferal δ18O, with distinctive short-term δ18O cycles superimposed. Coevally,
a permanent –1‰ change in oceanic δ13CDIC, the late Miocene carbon isotope shift
(LMCIS), marks the last major permanent shift in the carbon cycle expressed in all oceanic
basins, after which near-modern δ13C gradients are established around 6.7 Ma. Accurate
age control is crucial to ascertain the origin of the δ18O cyclicity and the LMCIS,
as constraining the precise timing of such events can allow temporal and causal
relationships to be established between the deep-sea, terrestrial and cryosphere
records.
Here, we present the first independent high-resolution chemo-, magneto-, and
cyclostratigraphy for the interval between 8.3-6.0 Ma from a single deep-sea site. Generated
at equatorial Pacific Integrated Ocean Drilling Program (IODP) Site U1337, our integrated
astronomically tuned benthic stable isotope stratigraphy (1.5 kyr resolution) and
magnetostratigraphy is suitable to test the current Tortonian-Messinian Geological
Time Scale (GTS2012), currently based on astronomically calibrated Mediterranean
sections. Between 7.7-6.9 Ma, the new benthic δ18O and δ13C data from IODP U1337
show distinctive obliquity-driven saw-tooth patterns suggesting that high-latitude
forcing dominated late Miocene climate dynamics. For the first time, the LMCIS is
astronomically calibrated and anchored to the GPTS between Chrons C4n.1n and
C3An.2n. Anchoring the LMCIS facilitates comparison with terrestrial records of the
C3/C4 vegetation shift, which has been linked to the LMCIS. The astronomically
calibrated Site U1337 magnetostratigraphy additionally provides robust ages for polarity
Chrons C3An.1n to C4r.1r, with ages changing by 2-50 kyr relative to the GTS2012.
The new integrated deep-sea stratigraphy from Site U1337 has potential as a new
stable isotope and magnetic polarity reference section for the 8.3-6.0 Ma interval. |
|
|
|
|
|
|