Richard Z. Poore Terrence M. Quinn Jessica W. Spear 2011 <p>Three years of weekly- to biweekly-resolved sediment-trap data show that almost 90% of the total flux of tests of the planktic foraminifer <i>Globorotalia truncatulinoides</i> to sediments in the northern Gulf of Mexico occurs in January and February. Comparison of δ¹⁸O from tests of non-encrusted <i>Gl. truncatulinoides</i> in sediment-trap samples with calculated calcification depths indicates that the non-encrusted individuals secrete their test in the winter surface-mixed layer, most likely at the bottom of the surface mixed zone. Mg/Ca-temperature estimates from non-encrusted <i>Gl. truncatulinoides</i> in sediment-trap samples are consistent with observed temperatures at the calcification depths inferred from the δ¹⁸O data. In contrast, Mg/Ca-temperature estimates from encrusted <i>Gl. truncatulinoides</i> in sediment-trap samples indicate the crust is formed in cooler (deeper) waters.</p> <br/> <p>A preliminary study in a core recovered near the sediment-trap site demonstrates that non-encrusted and encrusted forms of <i>Gl. truncatulinoides</i> in sediment samples show a similar offset in Mg/Ca values as observed in sediment-trap samples. A short (~ 100 years) Mg/Ca record from non-encrusted <i>Gl. truncatulinoides</i> indicates a warming trend that coincides with a warming trend in mean-annual sea-surface temperature recorded by Mg/Ca in <i>Globigerinoides ruber</i> (white) from the same core. These findings suggest Mg/Ca from non-encrusted <i>Gl. truncatulinoides</i> has clear potential as a proxy for past winter mixed-layer temperature.</p> application/pdf 10.1016/j.marmicro.2011.05.001 en Elsevier <i>Globorotalia truncatulinoides</i> (dextral) Mg/Ca as a proxy for Gulf of Mexico winter mixed-layer temperature: evidence from a sediment trap in the northern Gulf of Mexico article