 |
| Titel |
Stable isotope and benthic foraminiferal records of the Latest Danian Event at ODP Site 1262 (Walvis Ridge) |
| VerfasserIn |
Arne Deprez, Sofie Jehle, André Bornemann, Robert P. Speijer |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111771
|
| Publikation (Nr.) |
 EGU/EGU2015-11913.pdf |
|
|
|
|
|
| Zusammenfassung |
| The Latest Danian Event (LDE – aka Top Chron 27n Event) is characterized by a >1o
negative benthic foraminiferal CIE in various sections in Egypt, which has been correlated
with δ13C shifts of ~0.7o in Zumaia (Spain), Wombat Plateau (ODP 761B, Indian Ocean)
and Shatsky Rise (ODP 1209, Pacific Ocean) (Bornemann et al., 2009; Westerhold et al.,
2011). A concurrent ~0.5o δ18O excursion suggests a 2°C bottom water temperature rise
during this event at Shatsky Rise, suggesting a hyperthermal nature for this event (Westerhold
et al., 2011).
Here we show the first results of benthic foraminiferal faunal and isotope patterns related
to the LDE at Walvis Ridge (ODP Site 1262, Southern Atlantic Ocean, paleodepth ~3000 m).
The high percentage of planktic foraminifera (on average 99.2%) indicates good carbonate
preservation. Stable isotope analyses on the benthic foraminifer Nuttallides truempyi show a
~0.9o δ13C shift at ~62.2 Ma. Lowest values are measured at ~62.15 Ma. A concurrent
~0.8o δ18O excursion indicates a ~3°C temperature rise, larger than at Shatsky
Rise.
δ13C values recover to reach a transient plateau at 0.75o during the second Fe peak
(from ~62.1 to 62.0 Ma), coinciding with a second negative δ18O excursion of 0.7o. Also
the ODP Site 1209 (Shatsky Rise) record shows these double Fe, δ18O and δ13C peaks.
This is a feature that the LDE shares with some early Eocene hyperthermals, like
ETM-2/H1-H2 and I1-I2, and might point to a common origin as the early Eocene
hyperthermals.
The Walvis Ridge samples show a highly diverse assemblage of benthic foraminifera with
a relative abundance of 10-15% of Gyroidinoides spp. and ~10% of Nuttallides spp.,
Siphogenerinoides spp., Gavelinella spp., Epistominella spp. and Cibicidoides spp. The
~15cm sample interval dataset seems to show no large changes in relative abundance of these
species at the onset of the LDE.
This is different than faunal response to early Eocene hyperthermals, like ETM2. During
ETM2 at DSDP Site 401 (Bay of Biscay, NE Atlantic), oligotrophic conditions are inferred
because of the absence of opportunistic species (D’haenens et al., 2012). The ETM2 CIE of
0.76o at Site 401 is smaller than the LDE CIE at Walvis Ridge (0.9o), which is in contrast
to the seeming lack of benthic foraminiferal turnover at the LDE. However, the CIE during
ETM2 is significantly higher at other deep-sea sites (1.1-1.6o; D’haenens et al.,
2014).
Bornemann, A. et al., 2009. Journal of the Geological Society 166, 1135-1142.
D’haenens, S. et al., 2012. Marine Micropaleontology 88–89, 15-35.
D’haenens, S. et al., 2014. Paleoceanography 29, 370-388.
Westerhold, T. et al., 2011. Paleoceanography 26, PA2216. |
|
|
|
|
|
|