Rapidly accumulating manganese deposit from the Median Valley of the Mid‐Atlantic Ridge

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 Th230 and Pa231 with respect to the parent uranium isotopes in the sample. The accumulation rate is 100 to 200 mm/106 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.

[1]  P. Rona,et al.  The TAG hydrothermal field , 1974, Nature.

[2]  C. Lister.  Water percolation in the oceanic crust , 1974 .

[3]  H. Veeh,et al.  Origin of Metalliferous Sediments from the Pacific Ocean , 1973 .

[4]  Bonatti Enrico,et al.  Classification and genesis of submarine iron-manganese deposits , 1972 .

[5]  P. Rona,et al.  Manganese Crusts of the Atlantis Fracture Zone , 1972 .

[6]  Roger N. Anderson,et al.  Petrologic Significance of Low Heat Flow on the Flanks of Slow-Spreading Midocean Ridges , 1972 .

[7]  T. Ku,et al.  RADIOMETRIC EVIDENCE FOR THE RAPID GROWTH RATE OF SHALLOW-WATER, CONTINENTAL MARGIN MANGANESE NODULES. , 1972 .

[8]  C. Lister.  On the Thermal Balance of a Mid‐Ocean Ridge , 1972 .

[9]  W. Broecker,et al.  GEOCHEMISTRY OF THREE CORES FROM THE EAST PACIFIC RISE. , 1971 .

[10]  N. Watkins,et al.  The magnetic properties of igneous rocks from the ocean floor , 1971, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[11]  H. Veeh,et al.  Anomalous234U/238U on the East Pacific rise , 1971 .

[12]  K. Turekian,et al.  Deposition of Molybdenum and Uranium along the Major Ocean Ridge Systems , 1971, Nature.

[13]  W. Broecker,et al.  RADIOCHEMICAL STUDIES ON MANGANESE NODULES OF DEEP-SEA ORIGIN. , 1969 .

[14]  K. Boström,et al.  The origin of aluminum-poor ferromanganoan sediments in areas of high heat flow on the East Pacific Rise , 1969 .

[15]  W. Sackett.  Manganese Nodules: Thorium-230: Protactinium-231 Ratios , 1966, Science.

[16]  Konrad B. Krauskopf,et al.  Separation of manganese from iron in sedimentary processes , 1957 .