A total of 99 smear slides were made from Hole 1223A sediments in lithologic Units 1–3, 6, 7, 9, and 12–14 (Table T1). These slides were made of average sedimentary thickness and mounted on 22 mm x 40 mm coverslips using Norland optical adhesive. Additionally, six smear slides made by the Leg 200 shipboard scientific party from lithologic Units 3, 4, and 10 were included in our study. These slides were examined for microfossil content as well as to qualitatively estimate the concentration of clastic grains in the sediments. A simple technique was used to obtain a quantitative estimate of the frequency of Radiolaria by counting the number of specimens (whole and broken fragments) encountered on one lengthwise pass across the coverslip under the compound microscope with a 10x objective. This count was multiplied by a factor necessary to arrive at a frequency in terms of specimens per square centimeter of smear slide. The results of this investigation are shown Figure F2 and Table T1.
On the basis of our smear slide investigation, 31 samples of bulk sediments were selected for micropaleontological examination. These samples were placed in centrifuge tubes and immersed in a 50% saturated solution of sodium sulfate. A series of eight freeze-thaw cycles dispersed the clays, followed by wet sieving using a 44-µm sieve. Residues were mounted under 22 mm x 40 mm coverslips with Norland optical adhesive. The abundance of individual taxa observed on these slides is recorded in Table T2 as follows:
These abundance estimates have very limited precision and significance because the mounted residues are diluted by highly variable concentrations of volcanic glass and other clastic grains.