The response of SST to insolation and ice sheet variability from MIS 3 to MIS 11 in the northwestern Mediterranean Sea (Gulf of Lions)

Abstract

Here we present a sea surface temperature (SST) record based on the Uk′37 index from the PRGL1 borehole (Promess1) drilled on the upper slope of the Gulf of Lions (GL). This is the first continuous and high‐resolution record in the northwestern Mediterranean Sea from marine oxygen isotope stage 3 (MIS) 3 to MIS 11. Due the location of the GL, the SST proxy can be considered to be a reliable tool to study the climate link between high latitude and midlatitude. During glacial inceptions, the northern ice sheet signal via cold northwesterly winds was first recorded in our study area in comparison with southern locations, highlighting the strong sensitivity of this location to high‐latitude dynamics. Moreover, the amplitude of the millennial‐scale variability in the western Mediterranean basin seems to be the result of both ice sheet and insolation variability.

Western Mediterranean Sea Paleothermometry Over the Last Glacial Cycle Based on the Novel RI‐OH Index

“…(d) U K′ 37 (C 37 ketone unsaturation ratio; Prahl & Wakeham, ) with a conversion into November–May SSTs using the BAYSPLINE calibration by Tierney and Tingley (). Original U K′ 37 data from Cortina et al (). (e) Isotopic composition of the oxygen (δ 18 O) record of Globigerina bulloides : note the reversed axis.…”

“…These coelutions occurred because the MD99-2348/PRGL1-4 study site received substantial terrigenous inputs from the Rhône River during glacial periods (Cortina et al, 2016;Frigola et al, 2012;Pasquier et al, 2017Pasquier et al, , 2019Sierro et al, 2009). Therefore, at least some unknown portions of the alkenone-based record by Cortina et al (2015) could be affected by coelutions, especially during glacial maxima. Schouten et al, 2002) with a conversion into sea surface temperatures (SSTs) using the spatially varying BAYSPAR calibration by Tingley (2014, 2015).…”

“…(d) U K′ 37 (C 37 ketone unsaturation ratio; Prahl & Wakeham, 1987) with a conversion into November-May SSTs using the BAYSPLINE calibration by Tierney and Tingley (2018). Original U K′ 37 data from Cortina et al (2015). Figure 3c is the 1σ uncertainty in RI-OH-SSTs.…”

“…We have thus used the BAYSPLINE calibration to calculate November-May SSTs, with a prior SD set to 10°C. The highest U K′ 37 -SSTs of Cortina et al (2015) based on the calibration by Müller et al (1998) were below 23.4°C during the 160-9 ka BP period. Despite a small shift in U K′ 37 -SSTs by −0.5°C on average, no change in general trends or amplitudes is observed between the SST records calculated with the two calibrations.…”

“…In this study, we present one of the first RI‐OH‐based sea surface temperature (SST) records covering the 160–9 ka BP period from two adjacent marine cores located in the Gulf of Lions (western Mediterranean Sea) using the global calibration proposed by Lü et al (). Using independent paleothermometric proxies, including U K′ 37 (Cortina et al, ), we assess the validity of the new RI‐OH record and corresponding SST estimates. We then compare the interglacial‐glacial SST anomalies from the study site with a multiproxy selection of marine sites from the Iberian Margin, the Gulf of Cadiz, and the western Mediterranean Sea, including the Siculo‐Tunisian Strait.…”