Response of diatom and silicoflagellate assemblages in the central Gulf of California to regional climate change during the past 55 kyrs

Marine Micropaleontology
By: , and 



High-resolution studies of diatoms and silicoflagellates of the past 55 kyrs in cores MD02-2517/2515 from the central Gulf of California (GoC) reveal profound changes in GoC surface waters. Roperia tesselata, a diatom proxy for late winter–early spring upwelling, and Dictyocha stapedia, a subtropical silicoflagellate indicative of GoC sea surface temperatures (SSTs) > 24 °C, are common during the Holocene but rare during Marine Isotope Stage (MIS) 2 and most of MIS 3, a relationship that likely reflects a more northerly position of the North Pacific High (NPH) during the Holocene. In contrast during most of MIS 2 (~ 27–15 ka), the persistent presence of Distephanus speculum, a silicoflagellate associated with SSTs < 16°, suggests that cold, low salinity waters penetrated into the GoC, consistent with southward displacement of the NPH.

During MIS 3 (~ 55–27 ka), increased dominance of Azpeitia nodulifera (diatom) implies that stratified, tropical waters were present year round, whereas silicoflagellate assemblages suggest that stratified tropical conditions alternated with more productive, upwelling conditions on millennial timescales. Reduced biosiliceous productivity during Heinrich events likely reflected a reduction in both surface water nutrient levels and in the strength of northwest winds due to a weakened and more southerly NPH. Conversely, enhanced biosiliceous productivity during MIS 3 interstadials was probably linked to heightened nutrient levels and a strengthened NPH. Abrupt relative abundance increases of the silicoflagellate, Dictyocha aculeata, approximate the termination of MIS3 Heinrich events and may signal times when nutrient-rich deep waters associated with the resumption of enhanced Atlantic Meridional Overturning Circulation penetrated into the central Gulf.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Response of diatom and silicoflagellate assemblages in the central Gulf of California to regional climate change during the past 55 kyrs
Series title Marine Micropaleontology
DOI 10.1016/j.marmicro.2014.02.004
Volume 108
Year Published 2014
Language English
Publisher Elsevier
Contributing office(s) Volcano Science Center
Description 13 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Marine Micropaleontology
First page 28
Last page 40
Country United States
State California
Other Geospatial Gulf Of California
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