Faunal and solution patterns of planktonic Foraminifera in surface sediments of the South Pacific

Abstract

The distribution of planktonic Foraminifera in South Pacific sediments reflects the environments of production in surface waters and those of preservation on the ocean floor. Cluster analysis shows that distribution patterns have well-defined boundaries that correspond to the Subtropical Convergence, the Antarctic Polar Front, and the Peru-Chile Current in surface waters, and to the lysocline (level below which solution greatly increases) at depth. The interrelation of clusters is examined by temperature-solution rank analysis which shows how the great diversity of Foraminifera in tropical regions leads to a proliferation of clusters and how some clusters are derived from others by partial dissolution. The compensation depth, where Foraminifera disappear, is conceptually different from the lysocline which separates well-preserved from noticeably dissolved assemblages, and the two levels are not parallel. The variable thickness of the zone of partial dissolution between these levels suggests that the supply of calcareous shells and their dissolution tend to vary together, but in a non-linear fashion. Notes on selected species, including coiling-direction distributions, are appended.