Rapid Climate Changes in the Westernmost Mediterranean (Alboran Sea) Over the Last 35 kyr: New Insights From Four Lipid Paleothermometers (U^K'₃₇, TEX^H₈₆, RI‐OH', and LDI)

Abstract

The westernmost Mediterranean is one of the most sensitive areas to global climate change and high sedimentation rates allow recording high frequency variability. We present a high‐resolution paleotemperature reconstruction over the last 35 kyr using, for the first time, four independent organic sea surface temperature (SST) proxies (UK'37, TEXH86, RI‐OH' and LDI) based on alkenones, (hydroxy) isoprenoid GDGTs, and long‐chain diols. We also generated a δ18O of planktonic foraminifera G. bulloides record together with records of bulk parameters (total organic carbon content, δ13Corg) and the accumulation rates of different biomarkers to provide insights into terrestrial input and primary producers. All derived‐SST records showed similar trends over the last 35 kyr, revealing abrupt temperature variations during the last seven Dansgaard‐Oeschger (D/O) cycles, the three Heinrich (H) events, the Last Glacial Maximum, and the Younger Dryas. H3 is recognized as the coldest event, while H1 was recorded by all SST proxies as the most abrupt one. In general, TEXH86‐, RI‐OH'‐ and LDI‐SST estimates were lower than those obtained from UK'37. The LDI paleothermometer recorded the largest range of absolute SSTs over the whole period (ca. 20°C) followed by RI‐OH' (ca. 16°C). TEXH86, RI‐OH' and LDI proxies reflected sudden SST changes during the D/O 6 and 5 particularly well. Low BIT values and the abundance of C32 1,15‐diol in range with typical marine values indicated only minor input of continental organic matter. Accumulation rates of different lipid biomarkers were generally modulated by D/O cycles, suggesting enhanced productivity during D/O interstadials and the Bölling‐Alleröd period.

Disentangling Effects of Sea Surface Temperature and Water Depth on Hydroxylated Isoprenoid GDGTs: Insights From the Hadal Zone and Global Sediments

“…All the original data have been deposited publicly to the repository of Zenodo (https://doi.org/10.5281/zenodo.7114938). All the supporting data can be found in the cited references (Chen et al., 2020; Davtian & Bard, 2023; Davtian et al., 2019, 2021; Fietz et al., 2013, 2016; Huguet et al., 2013; Kaiser & Arz, 2016; Kremer et al., 2018; Lamping et al., 2021; L. Liu et al., 2022; Lü et al., 2015; Morcillo‐Montalba et al., 2021; Sinninghe Damste et al., 2022; Wei et al., 2020; Yang, 2017; Yang et al., 2018).…”

“…All the supporting data can be found in the cited references (Chen et al, 2020;Davtian & Bard, 2023;Davtian et al, 2019Davtian et al, , 2021Fietz et al, 2013Fietz et al, , 2016Huguet et al, 2013;Kaiser & Arz, 2016;Kremer et al, 2018;Lamping et al, 2021;L. Liu et al, 2022;Lü et al, 2015;Morcillo-Montalba et al, 2021;Sinninghe Damste et al, 2022;Wei et al, 2020;Yang, 2017;Yang et al, 2018).…”

“…(2015) proposed two Ring Indexes of OH‐GDGTs (namely RI‐OH and RI‐OH′; see Equations and in Section 2.4) based on the weighted average number of cyclopentane rings of OH‐GDGTs. RI‐OH and RI‐OH′ have been applied to reconstruct SSTs in diverse marine environments (Davtian & Bard, 2023; Davtian et al., 2019, 2021; Fietz et al., 2016; Kremer et al., 2018; Morcillo‐Montalba et al., 2021; Sinninghe Damste et al., 2022). Besides water temperature, other factors like water salinity (Sinninghe Damste et al., 2022), dissolved oxygen and nitrate (Harning et al., 2023), sea ice (Fietz et al., 2013), seasonality (Lü et al., 2019) and terrestrial input (Kang et al., 2017; Wei et al., 2020) may also affect the distribution of OH‐GDGTs in marine sediments.…”

Archaeal Hydroxylated Isoprenoid GDGTs in Asian Lake Sediments: A New Tool for Terrestrial Paleotemperature Reconstructions

“…In addition to %OH-GDGTs, RI-OH and RI-OH′ (two forms expressing the Ring Index of OH-GDGTs), another two indices based on the relative number of cyclopentane moieties in OH-GDGTs, have shown significant positive correlations with SST in marine settings (Lü et al, 2015(Lü et al, , 2019. While the RI-OH and RI-OH′ index have been used to reconstruct the past SSTs in several marine sediment cores (e.g., Davtian & Bard, 2023;Morcillo-Montalbá et al, 2021), it remains elusive whether these proxies can be directly applied in lacustrine settings.…”

Evidence for Marine Consumption During the Upper Palaeolithic at “El Pirulejo” Inland Rock- Shelter (Southern Iberia Peninsula, Spain)

“…The Iberian Peninsula served as a faunal and human refugium during the Last Glacial Maximum when vast areas of the European continent were covered by ice (Bhagwat & Willis 2008;Finlayson & Carrión 2007;Holt 2003;Stewart & Stringer 2012). The transition between the extreme cold Heinrich stadial 1 (H1) (17.9 to 15.7 cal kyr BP) to the abrupt warming during the Bølling-Allerød interstadial (B-A) (~15.7 cal kyr BP) (Camuera et al 2021), with an estimated increase in sea surface temperatures of ~10ºC (Morcillo-Montalbá et al 2021), witnessed the last significant genetic population bottleneck in Eurasian prehistory until the Neolithic (Morin 2008;Pardiñas et al 2012;Fu et al 2016). Despite the impact of this transition on human populations, little is known about these communities' diets due to the low number of archaeological sites.…”