ABSTRACT: Platinum Abundance in Ferromanganese Crusts and Nodules from the SW Pacific and Southern Oceans
Barrie R. Bolton, Reid R. Keays
The platinum concentrations of ferromanganese crusts and nodules from a wide latitudinal belt through the SW Pacific and Southern Oceans have been determined by ICP/MS and NAA techniques. Platinum abundance varies greatly with locality from 0.04 to 0.55 ppm and averages 0.22 ± 0.12 ppm in 28 samples. Palladium contents are also highly variable, ranging between 1.9 and 23 ppb and averaging 7.9 ± 6.0 ppb. Pt and Pd contents are significantly enriched over seawater concentrations (^sim200 pg1-1 and ^sim40 pg1-1, respectively), and the average crustal abundance (5 and 1.1 ppb, respectively. The Pt/Pd ratio ranges between 1.6 and 1182.
The ranges of Pt, Pd, and Pt/Pd values are similar to values reported in the literature for ferromanganese crusts and nodules from the Pacific and Antarctic regions.
Platinum concentrations appear to be controlled by water depth with maximum values occurring at the shallowest depths sampled (^sim1000 m). A similar depth control has been reported from other studies carried out in the Pacific basin. Platinum also shows a poorly defined relationship to latitude with peaks in concentration at about 18°S and 45°S.
Platinum correlates with Mn (r = 0.49), Co (r = 0.67), Ni (r = 0.62), and Zn (r = 0.46), which, together with the strong water depth control (r = -0.54), suggests a hydrogenetic origin possibly related to the oxygen-minimum zone.
AAPG Search and Discovery Article #90097©1990 Fifth Circum-Pacific Energy and Mineral Resources Conference, Honolulu, Hawaii, July 29-August 3, 1990