Deep-water temperature reconstruction of sediment core MD99-2334, supplement to: Skinner, Luke C; Shackleton, Nicholas J; Elderfield, Henry (2003): Millennial-scale variability of deep-water temperature and d18Odw indicating deep-water source variations in the Northeast Atlantic, 0-34 cal. ka BP. Geochemistry, Geophysics, Geosystems, 4(12)

• Main Authors: Skinner, Luke C, Shackleton, Nicholas J, Elderfield, Henry
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2003
• Subjects: Kasten corer; MD114; Marion Dufresne 1995; International Marine Global Change Study IMAGES; Antarctic; Greenland; Luke; Shackleton; Antarc*; Greenland ice cores; NADW; North Atlantic Deep Water; North Atlantic; Northeast Atlantic
• Online Access: https://dx.doi.org/10.1594/pangaea.738090; https://doi.pangaea.de/10.1594/PANGAEA.738090

Paired measurements of Mg/Ca and delta18O(cc) (calcite delta18O) in benthic foraminifera from a deep-sea core recovered on the Iberian Margin (MD99-2334K; 37°48'N, 10°10'W; 3,146 m) have been performed in parallel with planktonic delta18O(cc) analyses and counts of ice-rafted debris (IRD). The synchrony of temperature changes recorded in the Greenland ice cores and in North Atlantic planktonic delta18O(cc) allows the proxy records from MD99-2334K to be placed confidently on the GISP2 time-scale. This correlation is further corroborated by AMS 14C-dates. Benthic Mg/Ca measurements in MD99-2334K permit the reconstruction of past deep-water temperature (T(dw)) changes since ~34 cal. ka BP (calendar kiloyears before present). Using these T(dw) estimates and parallel benthic delta18O(cc) measurements, a record of deep-water delta18O (delta18O(dw)) has been calculated. Results indicate greatly reduced T(dw) in the deep Northeast Atlantic during the last glaciation until ~15 cal. ka BP, when T(dw) warmed abruptly to near-modern values in parallel with the onset of the Bølling-Allerød interstadial. Subsequently, Tdw reverted to cold glacial values between ~13.4 and ~11.4 cal. ka BP, in parallel with the Younger Dryas cold reversal and the H0 ice-rafting event. Similar millennial-scale T(dw) changes also occurred during the last glaciation. Indeed, throughout the last ~34 cal. ka, millennial delta18O(dw) and T(dw) changes have remained well coupled and are linked with IRD pulses coincident with Heinrich events 3, 2, 1, and the Younger Dryas, when transitions to lower T(dw) and delta18O(dw) conditions occurred. In general, millennial T(dw) and delta18O(dw) variations recorded in MD99-2334K describe an alternation between colder, low-delta18O(dw) and warmer, high delta18O(dw) conditions, which suggests the changing local dominance of northern-sourced North Atlantic Deep Water (NADW) versus southern-sourced Antarctic Bottom Water (AABW). The observed similarity of the T(dw) and GISP2 delta18O(ice) records would therefore suggest a common component of variability resulting from the coupling of NADW formation and Greenland climate. A link between Greenland stadials and the incursion of cold, low-delta18O(dw) AABW in the deep Northeast Atlantic is thus implied, which contributes to the relationship between Greenland climate and the millennial benthic delta18O(cc) signal since ~34 cal. ka BP.