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doi:10.2204/iodp.proc.303306.211.2010

Materials and methods

The uppermost Quaternary samples used in this study were collected from Site U1308. Site U1308 is a reoccupation of Deep Sea Drilling Project (DSDP) Leg 94 Site 609 and is located at 49°52.666′N, 24°14.287′W (Fig. F1). The uppermost Quaternary sediments at this site are composed mainly of nannofossil and foraminifer ooze. Samples were analyzed at ~10–20 cm intervals.

All samples were processed as follows:

1. Powdered sample (0.04 g) was put into a small beaker, and 50 mL of water was added to make a suspension.

2. Suspension medium (0.5 mL) was placed on a coverslip (18 mm x 18 mm) with a pipette.

3. The coverslip was dried on a hotplate.

4. Samples were mounted on a microslide using Norland optical adhesive.

Microslides were observed under a binocular polarizing microscope at 1500× magnification. A total of 200 nannofossil specimens, excluding Florisphaera profunda, were counted at random to determine their relative frequencies.

Preservation quality was assessed using five categories: very good and good for little or no evidence of dissolution and/or overgrowth, moderate for minor dissolution or crystal overgrowth, and poor and very poor for strong dissolution or crystal overgrowth, in which case many specimens are unidentifiable (Fig. F2). Reworked calcareous nannofossils were not documented in any of the samples.

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