ALBERT

Description: Supplementary material for Martínez Fontaine et al., 2019 (Table S1), including the radiocarbon ages in benthonic and planktonic foraminifera in six cores in the Chilean margin, beetween ~31°S and ~36°S (Table S3). The age models for the cores are detailed in Martínez Fontaine et al., 2019 and were produced using the information on planktonic δ13C (Table S2). Also included are the Δ14C resulting from the age models.

Description: Slowly accumulated (〈5 cm/kyr) and rapidly accumulated (5-20 cm/kyr) sediments have been compared to define the initiation and termination times of the most recent sapropel (S1) in the eastern Mediterranean Sea. The Ba/Al ratio has been employed as a more persistent index of productivity than Corg. Accelerator mass spectrometry radiocarbon dating of pelagic foraminifera indicates a maximum duration for increased Ba/Al levels in Sl from ~9500-6000 (uncorrected radiocarbon convention years B.P.) in the rapidly accumulated sediments and ~ 9500-5300 years B.P. in the slowly accumulated sediments. This difference is ascribed to bioturbation affecting the slower accumulated Sl sediments. In the two most rapidly accumulated Sl units, from the Adriatic and Aegean Seas, there is a 'saddle' of lower values centered on 7500 years B.P. in the Corg and Ba/Al profiles, so that the visual Sl unit appears as a doublet. Geochemical evidence indicates that this intervening period is best interpreted as an episode of increased ventilation and bottom water oxygenation during the period of sapropel accumulation.

Description: The Southern Ocean plays a prominent role in the Earth's climate and carbon cycle. Changes in the Southern Ocean circulation may have regulated the release of CO2 to the atmosphere from a deep-ocean reservoir during the last deglaciation. However, the path and exact timing of this deglacial CO2 release are still under debate. Here we present measurements of deglacial surface reservoir 14C age changes in the eastern Pacific sector of the Southern Ocean, obtained by 14C dating of tephra deposited over the marine and terrestrial regions. These results, along with records of foraminifera benthic-planktic 14C age and d13C difference, provide evidence for three periods of enhanced upwelling in the Southern Ocean during the last deglaciation, supporting the hypothesis that Southern Ocean upwelling contributed to the deglacial rise in atmospheric CO2. These independently dated marine records suggest synchronous changes in the Southern Ocean circulation and Antarctic climate during the last deglaciation.

Description: We present the neodymium isotopic composition (epsilon-Nd) of mixed planktonic foraminifera species from a sediment core collected at 622 m water depth in the Balearic Sea, as well as epsilon-Nd of scleractinian cold-water corals (CWC; Madrepora oculata, Lophelia pertusa) retrieved between 280 and 442 m water depth in the Alboran Sea and at 414 m depth in the southern Sardinian continental margin. The aim is to constrain hydrological variations at intermediate depths in the western Mediterranean Sea during the last 20 kyr. Planktonic (Globigerina bulloides) and benthic (Cibicidoides pachyderma) foraminifera from the Balearic Sea were also analyzed for stable oxygen (d18O) and carbon (d13C) isotopes. The foraminiferal and coral epsilon-Nd values from the Balearic and Alboran seas are comparable over the last ~13 kyr, with mean values of -8.94 ± 0.26 (1 Sigma; n = 24) and -8.91 ± 0.18 (1 Sigma; n = 25), respectively. Before 13 ka BP, the foraminiferal epsilon-Nd values are slightly lower (-9.28 ± 0.15) and tend to reflect higher mixing between intermediate and deep waters, which are characterized by more unradiogenic epsilon-Nd values. The slight epsilon-Nd increase after 13 ka BP is associated with a decoupling in the benthic foraminiferal d13C composition between intermediate and deeper depths, which started at ~16 ka BP. This suggests an earlier stratification of the water masses and a subsequent reduced contribution of unradiogenic epsilon-Nd from deep waters. The CWC from the Sardinia Channel show a much larger scatter of epsilon-Nd values, from -8.66 ± 0.30 to 5.99 ± 0.50, and a lower average (-7.31 ± 0.73; n = 19) compared to the CWC and foraminifera from the Alboran and Balearic seas, indicative of intermediate waters sourced from the Levantine basin. At the time of sapropel S1 deposition (10.2 to 6.4 ka), the epsilon-Nd values of the Sardinian CWC become more unradiogenic (-8.38 ± 0.47; n = 3 at ~8.7 ka BP), suggesting a significant contribution of intermediate waters originated from the western basin. We propose that western Mediterranean intermediate waters replaced the Levantine Intermediate Water (LIW), and thus there was a strong reduction of the LIW during the mid-sapropel (~8.7 ka BP). This observation supports a notable change of Mediterranean circulation pattern centered on sapropel S1 that needs further investigation to be confirmed.

Description: The comparison between different climate model simulations of water hosing experiments under glacial conditions points toward diverging responses in Sea Surface Temperature changes (SST) especially in the Southeast Pacific (SEP). This suggests that reconstituting the latitudinal SST gradient in the SEP is a critical parameter for a better understanding of the mechanisms behind the abrupt climatic events since the last glacial period. Here we present, high-resolution records of SST, using planktonic foraminiferal assemblages and alkenone temperature reconstructions and stable oxygen and carbon isotopes from three deep-sea sediment cores along a latitudinal transect off the southern Chilean coast. This allowed us to reconstruct the variations of the latitudinal SST gradient and the Subtropical Front movements in the SEP. The SST results suggest a clear Antarctic timing consistent with the bipolar seesaw control, especially during the late glacial and the deglaciation. Our records do not suggest a complete oceanic heat transfer signal, highlighting the implication of an atmospheric component in the heat transfers between the two hemispheres, controlled by the latitudinal movements of the intertropical convergence zone in the Atlantic and the associated weaker South Pacific westerly split jet. Furthermore, our records indicate variable conditions during the Holocene, and also emphasize the influence of local fresh water inputs from the Patagonian ice sheet and/or precipitation on the SST fresh water input estimates along the Chilean margin (North and South of 49° S) from the onset of the deglaciation until 8 kyr cal. BP.

Description: Supplementary material for Martínez Fontaine et al., 2021: Post–glacial tephrochronology record off the Chilean continental margin (~41° S). Including: Table S1.- Globigerina bulloides δ18O and the resulting age model for core MD07-3098 with its respective 1σ and 2σ envelopes. Table S2. Inividual glass shard analyses in core MD07-3100. Major elements not normalized‚ analyzed by EPMA‚ trace elements analyzed by LA-ICP-MS. Table S3. Inividual glass shard analyses in core MD07-3098. Major elements, not normalized, analyzed by EPMA. Table S5.- Planktonic foraminifera radiocarbon ages from core MD07-3098 and the respective marine surface reservoir age correction applied (Rs) in the calibration.