Hydrothermal Metalliferous Sediments

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1.1 What are metalliferous sediments?

Metalliferous sediments are unconsolidated deep-sea deposits that form in volcanically active areas of the ocean floor (Gurvich, 2006). These deposits are variable proportions of hydrothermal, detrital, hydrogenous, and biogenous material (Dymond et al., 1977). More simply defined, these are sediments with higher transition metal content than normal. These sediments are specifically enriched in iron, manganese and a number of other trace elements, while depleted in aluminum and titanium. This abiogenic matter is primarily produced and contributed to the ocean by means of hydrothermal vents, which emit sulfur and metal-bearing material into the ocean from Earth’s interior. Hydrothermal plumes of particle-laden fluid interact intimately with the surrounding seawater, where metal-rich marine precipitates then fall out of suspension and settle down to the ocean floor. Bonatti (1978) states that the essential feature of a metalliferous sediment is a hydrothermal Fe-Mn deposit that forms near active plate boundaries and hot spots.

2. Background

2.1 Discovery of metalliferous sediments

Although the first deep-sea metalliferous sample was recovered during the H.M.S. Challenger voyage of the southeastern Pacific, Murray and Renard (1891) did not recognize the anomalous nature of the sediment. Instead, credit for the discovery of the metallic nature of this sediment lies with Boström and Peterson (1966), as results from their experiment displayed a marked enrichment of Fe, Mn, Cu, Cr, Pb and Ni in sediments from the East Pacific Rise. Metal-rich sediments have since been recovered from a number of from a number of sites, most prominently on the East Pacific Rise and Mid-Atlantic Ridge, in the Bau...

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