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doi:10.2204/iodp.proc.342.111.2014

Age-depth model and mass accumulation rates

At Site U1410, we recovered a 260 m thick sequence of Pleistocene to lower Eocene nannofossil ooze and nannofossil clay with foraminifers and radiolarians. A relatively thick Pleistocene section overlies a condensed upper Miocene–upper middle Eocene section, which is followed by an expanded middle through lower Eocene succession. Hiatuses or highly condensed intervals occur between the lower Pleistocene and upper Miocene (7.1 m.y. duration), upper and lower Miocene (7.4 m.y. duration), lower Miocene and upper Oligocene (5.4 m.y. duration), and lower Oligocene and middle Eocene (7.4 m.y. duration). The Oligocene is highly condensed and may also contain substantial hiatuses. Sedimentation rates are 0.2 cm/k.y. through the Oligocene, 1.3–2.6 cm/k.y. through the middle Eocene, and 0.7 cm/k.y. through the lower Eocene.

Biostratigraphic and magnetostratigraphic datums from Hole U1410A (Table T3) were compiled to construct an age-depth model for this site (Fig. F22). A selected set of datums (Table T16) was used to create an age-depth correlation and calculate LSRs. Total mass accumulation rate (MAR), carbonate MAR (CAR), and noncarbonate MAR (nCAR) were calculated at 0.2 m.y. intervals using a preliminary shipboard splice rather than the sampling splice described in this volume (Table T17; Fig. F23).

Age-depth model

The age-depth model is tied to Pleistocene nannofossil and paleomagnetic datums in the upper 36 m of Hole U1410A. Nannofossil datums provide the sole tie points over a very condensed section that extends from the lower Pleistocene to the middle Eocene. This section includes two definite hiatuses and three very condensed intervals that probably also include hiatuses. Through the middle Eocene, nannofossil and paleomagnetic datums provide the primary tie points, with a single radiolarian datum serving as the final tie point in the core. Datums are in good agreement through the Eocene.

Linear sedimentation rates

This site is unique among sites drilled during this expedition in that it has a relatively expanded Pleistocene section with LSRs of 1.47–2.35 cm/k.y. This section is followed downhole by a condensed Pliocene–middle Eocene section with an average LSR of 0.19 cm/k.y. The middle to lower Eocene section has high LSRs in the upper part (1.98–2.63 cm/k.y.) that decrease progressively to a minimum of 0.66 cm/k.y. in the lower Eocene.

Mass accumulation rates

The Pleistocene sequence at Site U1410 has a MAR of 2.0 to 2.4 g/cm²/k.y., with a double peak largely driven by the LSR pattern. MAR is low in the Pliocene to middle Oligocene with a pattern of peak MAR values that correspond to changes in LSR. In the middle Eocene, MAR is 2.0–2.9 g/cm²/k.y., with roughly equal accumulation rates for carbonate and noncarbonate units. In the lower Eocene, carbonate contents increase to ~90 wt%, but overall MAR are significantly lower than the middle Eocene, with very low nCAR values.

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