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Rapidly accumulating manganese deposit from the Median Valley of the Mid‐Atlantic Ridge
Author(s) -
Scott Martha R.,
Scott Robert B.,
Rona Peter A.,
Butler Louis W.,
Nalwalk Andrew J.
Publication year - 1974
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl001i008p00355
Subject(s) - ferromanganese , geology , manganese , mid atlantic ridge , hydrothermal circulation , geochemistry , ridge , seamount , diagenesis , hot spring , sediment , crust , manganese oxide , mineralogy , geomorphology , paleontology , chemistry , organic chemistry
A manganese oxide crust from an extensive deposit in the median valley of the Mid‐Atlantic Ridge was found to be unusually high in manganese (up to 39.4% Mn), low in Fe (as low as .01% Fe), low in trace metals and deficient in Th 230 and Pa 231 with respect to the parent uranium isotopes in the sample. The accumulation rate is 100 to 200 mm/10 6 y, or 2 orders of magnitude faster than the typical rate for deep‐sea ferromanganese deposits. The rapid growth rate and unusual chemistry are consistent with a hydrothermal origin or with a diagenetic origin by manganese remobilized from reduced sediments. Because of the association with an active ridge, geophysical evidence indicative of hydrothermal activity, and a scarcity of sediment in the sampling area, we suggest that a submarine hot spring has created the deposit.