Matsui, Hiroki; Nishi, Hiroshi; Kuroyanagi, Azumi; Hayashi, Hiroki; Ikehara, Minoru; Takashima, Reishi (2020): δ¹⁸O and δ¹³C record of Paragloborotalia siakensis and Dentoglobigerina venezuelana from IODP Hole 321-U1337A [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.914391
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Abstract:
Knowledge of the equatorial thermocline is essential for understanding climate changes in the tropical Pacific. Multispecies planktic foraminiferal analyses provide a way to examine temperature distributions and thus the structure of the thermocline. Although the secular thermocline development has been documented back to the late Miocene, the early to middle Miocene interval has rarely been examined. In addition, relationships with the dynamic Antarctic ice sheets remain unclear. Here we investigate the vertical thermal gradient in the upper water column at Integrated Ocean Drilling Program Site U1337 in the eastern equatorial Pacific (EEP) throughout the early to middle Miocene (23.1 to 11.7 Ma). The gradient increased over the Miocene Climatic Optimum, whereas it decreased during the East Antarctic Ice Sheet Expansion (EAIE). Comparison of the EEP record with its western equatorial Pacific (WEP) counterpart suggests that sea surface temperature was more stable in the WEP than in the EEP. We further estimated equatorial thermocline from two diagonal gradients between the EEP and the WEP: thermocline shoaled from 16.7 to 15.7 Ma and tilt weakened between 16.5 and 13.8 Ma. The onset of the "Monterey Excursion" and the reduced Antarctic ice sheet volume would have affected thermocline depth and tilt, respectively. Thermocline depth was likely much deeper compared to Pliocene‐to‐modern conditions. Furthermore, a 4‐point‐based distribution of isotherms (4DI index) was used as a metric of the evenness or unevenness of the isotherm distributions. The 4DI index considerably reduced at around the EAIE and other Mi‐events, reflecting the evenly distributed isotherms under a more glaciated Antarctica.
Supplement to:
Matsui, Hiroki; Nishi, Hiroshi; Kuroyanagi, Azumi; Hayashi, Hiroki; Ikehara, Minoru; Takashima, Reishi (2017): Vertical thermal gradient history in the eastern equatorial Pacific during the early to middle Miocene: Implications for the equatorial thermocline development. Paleoceanography, 32(7), 729-743, https://doi.org/10.1002/2016PA003058
Further details:
Wilkens, Roy H; Dickens, Gerald Roy; Tian, Jun; Backman, Jan; Expedition 320/321 Scientists (2013): Data report: revised composite depth scales for Sites U1336, U1337, and U1338. In: Proceedings of the IODP, Integrated Ocean Drilling Program, https://doi.org/10.2204/iodp.proc.320321.209.2013
Project(s):
Coverage:
Latitude: 3.833445 * Longitude: -123.206035
Minimum DEPTH, sediment/rock: 226.79 m * Maximum DEPTH, sediment/rock: 448.82 m
Event(s):
321-U1337A * Latitude: 3.833445 * Longitude: -123.206035 * Elevation: -4472.0 m * Recovery: 420.11 m * Campaign: Exp321 (Pacific Equatorial Age Transect II / Juan de Fuca) * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 48 cores; 449.8 m cored; 93.4 % recovered; 0 m drilled; 449.8 m penetrated
Comment:
(1) = Analytical precisions are ±0.10‰ for δ¹⁸O and ±0.04‰ for δ¹³C, whereas blank indicates those are ±0.05‰ forδ¹⁸O and ±0.03‰ for δ¹³C.
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Sample code/label | Sample label | Matsui, Hiroki | DSDP/ODP/IODP sample designation | ||
| 2 | DEPTH, sediment/rock | Depth sed | m | Matsui, Hiroki | Geocode – mbsf | |
| 3 | Depth, composite revised, adjusted | Depth adj rmcd | armcd | Matsui, Hiroki | reported by Wilkens et al., 2013 | |
| 4 | AGE | Age | ka BP | Matsui, Hiroki | Geocode | |
| 5 | Paragloborotalia siakensis, δ13C | P. siakensis δ13C | ‰ PDB | Matsui, Hiroki | ||
| 6 | Paragloborotalia siakensis, δ18O | P. siakensis δ18O | ‰ PDB | Matsui, Hiroki | ||
| 7 | Sample comment | Sample comment | Matsui, Hiroki | to Paragloborotalia siakensis | ||
| 8 | Dentoglobigerina venezuelana, δ13C | D. venezuelana δ13C | ‰ PDB | Matsui, Hiroki | ||
| 9 | Dentoglobigerina venezuelana, δ18O | D. venezuelana δ18O | ‰ PDB | Matsui, Hiroki | ||
| 10 | Sample comment | Sample comment | Matsui, Hiroki | to Dentoglobigerina venezuelana |
License:
Creative Commons Attribution 4.0 International (CC-BY-4.0)
Size:
1016 data points