Abstract
Abstract. Ocean Drilling Program (ODP) Site 982 provided a key sediment section at Rockall Plateau for reconstructing northeast Atlantic paleoceanography and monitoring benthic δ18O stratigraphy over the late Pliocene to Quaternary onset of major Northern Hemisphere glaciation. A renewed hole-specific inspection of magnetostratigraphic reversals and the addition of epibenthic δ18O records for short Pliocene sections in holes 982A, B, and C, crossing core breaks in the δ18O record published for Hole 982B, now imply a major revision of composite core depths. After tuning to the orbitally tuned reference record LR04, the new composite δ18O record results in a hiatus, where the Kaena magnetic subchron might have been lost, and in a significant age reduction for all proxy records by 130 to 20 ky over the time span 3.2–2.7 million years ago (Ma). Our study demonstrates the general significance of reliable composite-depth scales and δ18O stratigraphies in ODP sediment records for generating ocean-wide correlations in paleoceanography. The new concept of age control makes the late Pliocene trends in SST (sea surface temperature) and atmospheric pCO2 at Site 982 more consistent with various paleoclimate trends published from elsewhere in the North Atlantic.
Highlights
Several studies used the Pliocene sediment section of Ocean Drilling Program (ODP) Site 982 (Rockall Plateau; 57◦3 N, 15◦5 W; 1134 m water depth) in the North Atlantic for paleoceanographic reconstructions
We supplemented the epibenthic δ18O record of Hole 982B and added intervals of records from holes 982A and C in order to bridge more accurately various coring gaps (Table S1; see Supplement). Using this approach we identified and had to insert small additional core sections previously overlooked by the Shipboard Scientific Party (1996) in the composite depth scheme
In contrast to previous schemes of age control (Venz and Hodell, 2002; Lisiecki and Raymo, 2005; Lawrence et al, 2009), we replaced – here without changing the composite-depth scale published by the Shipboard Scienific Party (1996) – the M/G boundary in Hole 982A by that in Hole 982B (Channell and Lehmann, 1999), which occurs ∼0.78 m farther downhole and corresponds directly to marine isotope stage (MIS) 104 in the Hole-B δ18O record
Summary
Several studies used the Pliocene sediment section of Ocean Drilling Program (ODP) Site 982 (Rockall Plateau; 57◦3 N, 15◦5 W; 1134 m water depth) in the North Atlantic for paleoceanographic reconstructions. The Leg 162 Shipboard Scientific Party (1996) first established an age control at Site 982 for the upper Pliocene (∼3.65–2.60 Ma) by means of both magnetic reversals in Hole A (with regard to the Matuyama-Gauss boundary; Channell and Lehmann, 1999; Channell and Guyodo, 2004) and an epibenthic δ18O record mostly obtained from Hole B (Venz and Hodell, 2002). We supplemented the epibenthic δ18O record of Hole 982B and added intervals of records from holes 982A and C in order to bridge more accurately various coring gaps (Table S1; see Supplement). Using this approach we identified and had to insert small additional core sections previously overlooked by the Shipboard Scientific Party (1996) in the composite depth scheme. Khelifi et al.: Technical note: Late Pliocene age control at ODP Site 982, revisited
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