ALBERT

Description: To study shifts in phytoplankton proxies linked to terrigenous inputs and teleconnections, we analyze the composite core MV99 GC41/PC14 from Soledad Basin, Gulf of Ulloa, NW Mexico. We used biogenic opal (% opal), organic carbon (% TOC) and inorganic carbon (% CaCO3) as proxies of productivity; and opal/TOC and CaCO3/TOC ratios as proxies of nutrient uptake and C-export by siliceous and carbonate organisms. We reconstructed terrestrial inputs using grain size Weibull analyses. Grain size analyses show significant amounts of fine fraction (between 0.06 - 6.6 µm) present during the early- to mid-Holocene in agreement to extreme weather on land, with episodes of aeolian and fluvial transport to the sea. The found that ENSO-like variations influence biological C-export producers on a scale of 1.1-1.8 ka, although PDO-related variability is uncertain. We suggest that Holocene drivers for phytoplankton successions are changes in insolation, ITCZ migration, California Current upwelling, nutrient inputs by advection and terrestrial sources.

Description: We present new high-resolution N isotope records from the Gulf of Tehuantepec and the Nicaragua Basin spanning the last 50-70 ka. The Tehuantepec site is situated within the core of the north subtropical denitrification zone while the Nicaragua site is at the southern boundary. The d15N record from Nicaragua shows an 'Antarctic' timing similar to denitrification changes observed off Peru-Chile but is radically different from the northern records. We attribute this to the leakage of isotopically heavy nitrate from the South Pacific oxygen minimum zone (OMZ) into the Nicaragua Basin. The Nicaragua record leads the other eastern tropical North Pacific (ETNP) records by about 1000 years because denitrification peaks in the eastern tropical South Pacific (ETSP) before denitrification starts to increase in the Northern Hemisphere OMZ, i.e., during warming episodes in Antarctica. We find that the influence of the heavy nitrate leakage from the ETSP is still noticeable, although attenuated, in the Gulf of Tehuantepec record, particularly at the end of the Heinrich events, and tends to alter the recording of millennial timescale denitrification changes in the ETNP. This implies (1) that sedimentary d15N records from the southern parts of the ETNP cannot be used straightforwardly as a proxy for local denitrification and (2) that denitrification history in the ETNP, like in the Arabian Sea, is synchronous with Greenland temperature changes. These observations reinforce the conclusion that on millennial timescales during the last ice age, denitrification in the ETNP is strongly influenced by climatic variations that originated in the high-latitude North Atlantic region, while commensurate changes in Southern Ocean hydrography more directly, and slightly earlier, affected oxygen concentrations in the ETSP. Furthermore, the d15N records imply ongoing physical communication across the equator in the shallow subsurface continuously over the last 50-70 ka.

Description: In the sediment Core EN-032-18PC, collected below the influence of the Loop Current in the eastern Gulf of Mexico, we aimed to investigate mixed layer conditions, the intensity of the surface and subsurface waters flowing from the Caribbean to the gulf, and the extension of the Loop Current. We analyzed 136 samples that include: (S1) Bulk sediment and sand fraction (〉62 μm) weight (g), the absolute abundance (tests per sample) of 33 species of planktonic foraminifera. (S2) Relative abundance (%) of planktonic foraminifera and factor loadings of two factors (Q-mode factor analysis). (S3) Stable isotopes (δ18O-PDB and δ13C-PDB) (‰) of Globigerinoides ruber (white) and the loess-smoothing of the series with polynomial regression.

Description: This is an update of and extension of the MARGO compilation of planktonic foraminifera assemblages for the Last Glacial Maximum (19,000-23,000 ka BP). It includes all data previously compiled within the MARGO project, with some minor corrections (indicated in QCNote), data published since and new counts. The taxonomy has been updated and harmonised to be directly comparable with the ForCenS core top data set (https://doi.pangaea.de/10.1594/PANGAEA.873570; https://doi.org/10.1038/sdata.2017.109). Criteria for inclusion of new data followed those of MARGO, including the ranking of chronological confidence (https://doi.org/10.1016/j.quascirev.2004.07.017). All data pertain to the size fraction 〉150 µm. Absolute counts are provided whenever these were available; no attempt has been made to correct published relative abundance data when their sum deviated from unity. The data are made available in wide format with metadata with self-explainable headers.