Previous   |    Next

doi:10.2204/iodp.proc.330.201.2014

Methods

The calcareous nannofossils discussed here were examined in smear slides prepared using microscope slides and coverslips that were mounted with Norland optical adhesive. These slides were observed using standard light microscope techniques on a Zeiss Photoscope 3 with cross-polarized and plane-transmitted light at 1000× magnification. A minimum of two traverses were examined for each sample, one in cross-polarized light and another in plane-transmitted light, with additional scanning of the slide for rare specimens. The zonation of Okada and Bukry (1980) was applied for Cenozoic calcareous nannofossils, whereas the zonation of Sissingh (1977) was used for the Upper Cretaceous. Taxonomy follows that of Bown (1998) and Perch-Nielsen (1985), where full taxonomic lists can be found. Complete lists of species identified by sample can be found in Table T1.

Estimates of the abundance of calcareous nannofossils were determined as follows:

• D = dominant (>100 specimens per field of view).
• A = abundant (>10–100 specimens per field of view).
• C = common (1–10 specimens per field of view).
• F = few (1 specimen per 1–10 fields of view).
• R = rare (<1 specimen per 10 fields of view).
• B = barren.

Preservation of calcareous nannofossils was classified as follows:

• VG = very good (no evidence of dissolution and/or recrystallization, no alteration of primary morphological characteristics, and all specimens identifiable to the species level).
• G = good (little or no evidence of dissolution and/or recrystallization, primary morphological characteristics only slightly altered, and specimens identifiable to the species level).
• M = moderate (some etching and/or recrystallization, primary morphological characteristics somewhat altered, and most specimens identifiable to the species level).
• P = poor (severe etching or overgrowth, primary morphological characteristics largely destroyed, fragmentation has occurred, and specimens often unidentifiable at the species and/or generic level).

Top of page   |    Previous   |    Next