Variations in the Fine-Scale Composition of a Central Pacific Ferromanganese Crust: Paleoceanographic Implications

摘要: A 47- to 60-mm-thick Fe-Mn crust from Horizon Guyot (water depth 1800–1780 m), central Pacific, was used evaluate the potential of crusts as recorders Neogene paleoceanographic and paleoclimatic conditions. The chemical composition determined by microprobe for 16 elements a polished thin section. Three analyses were made per millimeter averaged give each millimeter. age measuring strontium isotope comparing it with Tertiary seawater curve. represents 18.5 m.y. growth Fe Mn oxyhydroxides. is composed alternating botryoidal laminated layers. layers formed during same time intervals that widespread deep-sea hiatuses forming in bottom sediments. represent times intensified deepwater flow, whereas more quiescent correspondence between so strong we able choose variable rate model over constant crust. Chemical changes take two forms. first represented broad defined chiefly fourth-order polynomial fits profiles element second high-frequency composition. broader occurred primarily at about 15, 11.5, 7.4, 6.4, 5.2, 4.6 Ma, which may correlate major circulation development ice caps poles. periods reflect climatic resulted orbital forcing. These correspond high-order eccentricity 3.47, 2.04, 1.31