Chemostratigraphic documentation of a complete Miocene intermediate-depth section in the Southern Ocean: Ocean Drilling Program Site 1120, Campbell Plateau off New Zealand

Abstract An integrated chemostratigraphic ( 87 Sr/ 86 Sr, δ 13 C and δ 18 O) study of benthic foraminifera is presented for a 210 m-thick, intermediate depth (upper/middle bathyal transition), Miocene nannofossil ooze section of Ocean Drilling Program Site 1120, Campbell Plateau off New Zealand. Our results indicate that new 87 Sr/ 86 Sr, δ 13 C and δ 18 O profiles are wholly consistent with their respective Miocene reference curves. These observations facilitate identification of a total of five reliable chemostratigraphic datums, which are based on the fundamental structural changes in the 87 Sr/ 86 Sr curve and paired simultaneous δ 13 C and δ 18 O events. The resultant age–depth relationship clearly shows that the Miocene (20–5 Ma) biopelagic sedimentation on the Campbell Plateau was essentially continuous at a moderate to high, linear sedimentation rate (17.5 m/m.y. with an exception of the uppermost 13 m). Our findings do not support the shipboard biostratigraphic age model, which assumes that the critical early–middle Miocene transition was interrupted by a major hiatus (