The evolution of the equatorial thermocline and the early Pliocene El Padre mean state. Issue 12 (18th June 2015)

• Record Type: Journal Article
• Authors: Ford, Heather L.; Ravelo, A. Christina; Dekens, Petra S.; LaRiviere, Jonathan P.; Wara, Michael W.
• Is Part Of: Geophysical research letters. Volume 42:Issue 12(2015:Jun.)
• Page Start: 4878
• Page End: 4887
• Publication Date: 2015-06-18
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2015GL064215
• Languages: English
• ISSNs: 0094-8276

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>The tropical Pacific thermocline strength, depth, and tilt are critical to tropical mean state and variability. During the early Pliocene (~3.5 to 4.5 Ma), the Eastern Equatorial Pacific (EEP) thermocline was deeper and the cold tongue was warmer than today, which resulted in a mean state with a reduced zonal sea surface temperature gradient or <italic>El Padre</italic>. However, it is unclear whether the deep thermocline was a local feature of the EEP or a basin‐wide condition with global implications. Our measurements of Mg/Ca of <italic>Globorotalia tumida</italic> in a western equatorial Pacific site indicate Pliocene subsurface temperatures warmer than today; thus, <italic>El Padre</italic> included a basin‐wide thermocline that was relatively warm, deep, and weakly tilted. At ~4 Ma, thermocline steepening was coupled to cooling of the cold tongue. Since ~4 Ma, the basin‐wide thermocline cooled/shoaled gradually, with implications for thermocline feedbacks in tropical dynamics and the interpretation of TEX₈₆‐derived temperatures.</p> </abstract>