TY - JOUR
AU - L. Skinner
AU - N. Shackleton
AB - Benthic and planktonic oxygen isotope (δ18Occ) and Mg/Ca analyses in two cores from the Northeast Atlantic have permitted the reconstruction of surface- and deep-water temperature (Tdw) and δ18O (δ18Ow) variations across the last two deglaciations. These records allow the timing of de-glacial melt-water pulses reaching the Northeast Atlantic to be compared with the evolution of local deep-water Tdw\textendashδ18Ow conditions. Although each glacial termination is unique in detail, a similar pattern of hydrographic change is reconstructed for both deglaciations, with the first major decrease in deep-water δ18Ow (due to sea-level and/or purely local deep-water change) occurring in parallel with the onset of intensely cold glacial surface-water temperatures, and prior to a \textquoteleftterminal\textquoteright ice-rafting and melt-water event. The evolution of deep-water across both de-glaciations involved two transient incursions of cold, low-δ18O water into the deep Northeast Atlantic, the second of which was particularly pronounced each time. These pulses of cold deep-water are interpreted to reflect the incursion of water directly analogous to modern Antarctic Bottom Water (AABW), and containing a significant component of brine rejected during sea-ice formation. The results presented here show that the same type of transient changes in deep-water circulation that occurred across Termination I also occurred across Termination II, and that as a result of these deep-ocean changes, the timing of each benthic δ18O \textquotelefttermination\textquoteright cannot precisely reflect the timing of de-glacial sea-level change, as many palaeoceanographic interpretations (and some controversies) are prone to assume. Such \textquoteleftimprecision\textquoteright (in timing especially) may well extend to marine isotope stage (MIS) boundaries in general, as a principle of hydrographic variability and its expression in the geological record.
BT - Quaternary Science Reviews
M1 - 23-24
N1 - doi: 10.1016/j.quascirev.2006.07.005
N2 - Benthic and planktonic oxygen isotope (δ18Occ) and Mg/Ca analyses in two cores from the Northeast Atlantic have permitted the reconstruction of surface- and deep-water temperature (Tdw) and δ18O (δ18Ow) variations across the last two deglaciations. These records allow the timing of de-glacial melt-water pulses reaching the Northeast Atlantic to be compared with the evolution of local deep-water Tdw\textendashδ18Ow conditions. Although each glacial termination is unique in detail, a similar pattern of hydrographic change is reconstructed for both deglaciations, with the first major decrease in deep-water δ18Ow (due to sea-level and/or purely local deep-water change) occurring in parallel with the onset of intensely cold glacial surface-water temperatures, and prior to a \textquoteleftterminal\textquoteright ice-rafting and melt-water event. The evolution of deep-water across both de-glaciations involved two transient incursions of cold, low-δ18O water into the deep Northeast Atlantic, the second of which was particularly pronounced each time. These pulses of cold deep-water are interpreted to reflect the incursion of water directly analogous to modern Antarctic Bottom Water (AABW), and containing a significant component of brine rejected during sea-ice formation. The results presented here show that the same type of transient changes in deep-water circulation that occurred across Termination I also occurred across Termination II, and that as a result of these deep-ocean changes, the timing of each benthic δ18O \textquotelefttermination\textquoteright cannot precisely reflect the timing of de-glacial sea-level change, as many palaeoceanographic interpretations (and some controversies) are prone to assume. Such \textquoteleftimprecision\textquoteright (in timing especially) may well extend to marine isotope stage (MIS) boundaries in general, as a principle of hydrographic variability and its expression in the geological record.
PY - 2006
SN - 0277-3791
SP - 3312
EP - 3321
T2 - Quaternary Science Reviews
TI - Deconstructing Terminations I and II: revisiting the glacioeustatic paradigm based on deep-water temperature estimates
UR - http://www.sciencedirect.com/science/article/pii/S0277379106002307
VL - 25
ER -