Data Report: Miocene benthic foraminiferal abundances and dissolution indices, Site 1006, Straits of Florida

Abstract

Samples were washed with sodium metaphosphate (5.5 g/L) in tap water through a 63-μm sieve and air dried. Benthic foraminifers were picked from aliquots of the >150-μm size fraction and mounted on reference slides. We avoid the 63to 150-μm size fraction preferred by some authors (e.g., Schroder et al., 1987) because of problems in identifying small taxa. While we lose information obtainable from the 63to 150-μm size fraction, we gain information on larger taxa (i.e., in an aliquot picked from the >63-μm size fraction, many larger taxa are underemphasized, while small, difficult to identify taxa are emphasized). In general, ~300 specimens were picked per sample. However, samples with as few as 130 specimens were used in the faunal analyses. Thirty-seven samples were examined for this study (Table 1). Our identifications of most of the benthic foraminifers follow the taxonomy of van Morkhoven et al. (1986); additional taxonomic references include Katz and Miller (1993a, 1993b), and references included therein. Not all species present were identified; for example, species of some common (Lenticulina, Oridorsalis, and Gyroidinoides) and some rare (Lagena, Fissurina, and Oolina) genera were not differentiated. We performed Q-mode principal components and varimax factor analyses on the relative abundance (percentage) data using modifications of programs provided by Lohmann (1980). The Q-mode principal components and varimax factor programs utilize a cosine-theta matrix, standardizing each sample to unit length. Each factor represents a unique benthic foraminiferal biofacies. We used factor analysis to help identify trends in the benthic foraminiferal biofacies at Site 1006, using two analyses: (1) the first was run using the entire benthic foraminiferal data set (Fig. 1); and (2) the second analysis was run with the transported, shallow-water taxa deleted and only the in situ faunal components were used (Fig. 2). Dissolution indices (Table 1) were based on counts of planktonic foraminifer fragments, whole planktonic foraminifer tests, and benthic foraminifer tests. Percentages of planktonic foraminifer fragments were calculated relative to fragments plus whole planktonic foraminifer tests. Percentages of planktonic foraminifers were calculated relative to whole planktonic plus benthic foraminifer tests.