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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The Kimmeridge Clay Formation is the penultimate formation of the onshore British Jurrasic Succession. William Smith was the first to document this distinct formation on his map of 1815, and to name as the Oaktree Soil. In 1817, he gave the name Oaktree Clay for the layers of clay between the “Portland Rock” and “Coral Rag and Pisolite” but in 1816 Webster was the first to describe in details the formation and changed to the name now known as kimmeridge Clay Formation after the English village of Kimmeridge on Dorset’s “Jurassic Coast” a place frequently visited by fossil hunters. (Cox and Gallois, 1981).
The Starved Rock Member of the Saint Peter Sandstone is preserved as a northeast-southwest trending belt of strata that is ...
Bowens, Amanda. Underwater Archaeology: The NAS Guide to Principles and Practice. Malden, MA: Blackwell Pub., 2009. Print.
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Wood and Kienle, 1990, Volcanoes of North America: United States and Canada: Cambridge University Press, 354 p., p. 158-160, Contribution by Patrick Pringle.
The coastal belt of the Franciscan Complex is composed of the youngest and least deformed units and makes up the western quarter of all Franciscan rocks. The rocks of the coastal belt are composed of arkosic sandstones, andesitic graywackes, and quartzofeldspathic graywackes interbedded with radiolarian chert (turbidite deposits) (Blake and Jones, 1981). These sedimentary rocks suggest a depositional environment of deep-sea fan systems with both oceanic and continental provenance. Parts of the belt show evidence of later metamorphism, principally due to subduction. Low-grade blueschist mineral facies are indicated by the presence of minerals such as laumonite and prehnite-pumpellyite (Blake and Jones, 1981). All rock units show evidence of thrust (imbricate) faulting due to the compressional forces of subduction. Ages of the coastal belt run from as little as 40 Ma (Eocene) to as old as 100 Ma (middle Cretaceous).
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Minerals play an important role in our day-to-day life but we often not contemplate how the minerals are obtained. Minerals are scattered all over the world just like any other resources. Due to the natural processes of magma flow, hydrothermal gradients, sedimentation, and evaporation, Minerals are concentrated in various areas of the Earth’s crust. Obtaining these minerals for human use involves four general steps:
Geology and Mineral Resource Assessment of the Venezuelan Guayana Shield. (n.d.). USGS. Retrieved November 12, 2013, from http://pubs.usgs.gov/bul/2062/report.pdf
Magmas in island arc settings consist primarily of components from two different origins, the slab component, and the mantle wedge. The mantle wedge may melt due the descent of the slab, giving the main portion of the non-slab component. The slab component is derived from the subducting slab as it descends. This may consist of melting of the crustal portion of the slab, but also melting of the mantle wedge due to addition of water driven off the slab. Since the descending slab is composed of old, cold oceanic crust, there is a slight paradox in the idea of melts forming from it. However, frictional heat, as well as the heat of the underlying mantle, can drive hydrous fluids off the slab. (Machado, Chemale Jr., Conceição, Kawashita, Morata, and Van Schmus, 2003; Kimura and Yoshida, 2006).The addition of water to the mantle wedge results in the lowering of melting temperatures, allowing melts to be formed at much lower temperatures than might otherwise be expected. Also, the circulation of hot fluids allows materials dissolved in them to migrate upwards ...
Eckel, Edwin B., ed. Nevada Test Site. Memoir 110 Boulder, CO: The Geological Society of America, 1968
Review: The opportunity and endeavor of exploring the Earth’s oceans can reap great rewards for mankind and unravel many of the mysteries that the Earth has left to discover.