Jingjing Liu1, Jun Tian1*, Zhonghui Liu2*, Timothy D. Herbert3, Alexey V. Fedorov4, Mitch Lyle5
1State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China.
2Department of Earth Sciences, The University of Hong Kong, Hong Kong, China.
3Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA.
4Department of Geology and Geophysics, Yale University, New Haven, CT 06520, USA.
5College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA
The timing and mechanisms of the eastern equatorial Pacific (EEP) cold tongue development, a salient feature of the tropical ocean, are intensely debated on geological time scales. Here, we reconstruct cold tongue evolution over the past 8 million years by computing changes in temperature gradient between the cold tongue and eastern Pacific warm pool. Results indicate that the cold tongue remained very weak between 8 and 4.3 million years ago, implying much weaker zonal temperature gradients prevailing during the late Miocene–Pliocene, but then underwent gradual intensification with apparently increasing sensitivity of the cold tongue to extratropical temperature changes. Our results reveal that the EEP cold tongue intensification was mainly controlled by extratropical climate.
Fig. 3 EEP CT development compared with other representative surface and subsurface records.
(A) Benthic foraminiferal δ18O of site U1337 ( 47). (B) Meridional SST gradient between sites 846 and 1208. (C) Zonal SST gradient between sites 806 and 846. (D) ΔSSTU1337–846. (E) Mg/Ca subsurface temperature records at ODP sites 849 and 1241. (F) Δδ18O999–851, the δ18O difference between ODP sites 851 and 999, with the green line denoting three-point running mean, and subsurface temperature at site 999. NHG, the Northern Hemisphere Glaciation; BF, benthic foraminiferal; PF, planktonic foraminiferal. SST data are from (14, 22, 23, 52), and δ18O [in (F)] and subsurface data are from (8, 9, 37). A more completed display can be found in figs. S2, S6, and S7.
Full Article: http://advances.sciencemag.org/content/5/4/eaau6060