Depositional coasts

The chemical nature of amber is complex. Amber consists of complex mixtures of sesquiterpenoids, diterpenoids, and triterpenoids that have undergone polymerization and molecular reorganization during fossilization. Phenolic units may also be present. Baltic coast deposits, which contain about 8% succinic acid, are often called succinite. Amber is amorphous, and its infrared spectrum closely resembles those of nonvolatile resins from extinct pine trees. It is believed not to be a high polymer, the resinous state being accounted for by the complexity of materials present. Amber also serves as a repository for a variety of extinct species of insects. 

Sodium is not found ia the free state ia nature because of its high chemical reactivity. It occurs naturally as a component of many complex minerals and of such simple ones as sodium chloride, sodium carbonate, sodium sulfate, sodium borate, and sodium nitrate. Soluble sodium salts are found ia seawater, mineral spriags, and salt lakes. Principal U.S. commercial deposits of sodium salts are the Great Salt Lake Seades Lake and the rock salt beds of the Gulf Coast, Virginia, New York, and Michigan (see Chemicals frombrine). Sodium-23 is the only naturally occurring isotope. The six artificial radioisotopes (qv) are Hsted ia Table 1 (see Sodium compounds). 

Salt-Dome Sulfur Deposits. The sulfur deposits associated with salt domes in the Gulf Coast regions of the southern United States and Mexico have historically been the primary sources of U.S. sulfur. These remain an important segment of both U.S. and world sulfur supply. Although the reserves are finite, many are large and voluntary productive capacity ensures the importance of these sources for some time to come. In 1994, the output from the salt domes in the U.S. was about 2.09 million metric tons (21). 

Evaporite Basin Sulfur Deposits. Elemental sulfur occurs in another type of subsurface deposit similar to the salt-dome stmctures in that the sulfur is associated with anhydrite or gypsum. The deposits are sedimentary, however, and occur in huge evaporite basins. It is befleved that the sulfur in these deposits, like that in the Gulf Coast salt domes, was derived by hydrocarbon reduction of the sulfate material and assisted by anaerobic bacteria. The sulfur deposits in Italy (Sicily), Poland, Iraq, the CIS, and the United States (western Texas) are included in this category. 

Diamonds were first discovered in ancient times in India and Borneo and later in Brazil in 1670 in alluvial deposits where water had sorted minerals on the basis of density and toughness. This type of tumbling often concentrates the better quality crystals such as those found in the ocean off the west coast of Africa. Exploration can be done by stream panning or drilling in conjunction with a search for the heavy mineral assemblages that accompany diamond. Alluvial deposits account for about 40% of the diamond found in primary sources. 

Several countries supply monazite concentrates for the world market. Extensive deposits along the coast of western AustraUa are worked for ilmenite and are the primary source of world monazite. Other regions of AustraUa, along with India and Brazil, also supply the mineral. Because monazite contains thorium [7440-29-1], India and Brazil have embargoed its export for many years. In the United States, commerce in the mineral is regulated by the Nuclear Regulatory Commission. 

Gulf Coast region of the USA and Mexico, and from the evaporite basin deposits in west Texas, Poland, the former USSR and Iran. 

In 1970 a huge deposit of methane hydrate was discovered at the bottom of the Atlantic Ocean, 330 km off the coast of North Carolina. 

The first reports of plastic in the North Atlantic indicated the presence of 50-12,000 particles/km in the Sargasso Sea in 1972 (52) and from 0-14.1 particles per m in coastal waters of southern New England (42), where the main source was river-borne effluents from plastic fabrication plants (44). Plastic objects discarded from boats and from recreational activities on beaches were the main sources of debris in Narragansett Bay, being deposited at a rate of 9.6 g m of beach front per month (53). During a detailed survey off the southeast coast of the United States (43, 54), fragments of plastic were present in about 70% of the samples collected from the waters of the continental shelf, the continental slope and the Gulf Stream between Florida and Cape Cod, 50% of those from the Caribbean Sea, and 60% of those from the Antilles Current. Since unprocessed plastic was more prevalent in continental shelf waters and fabricated objects were common offshore but rare near land, the authors surmised... 

It may seem unlikely that all these conditions could have been met, but at least one deposit of uranium ore has characteristics indicating that, long ago, it operated as a natural nuclear reactor. At Oklo in the Gabon Republic near the western coast of equatorial Africa (see photo), there are uranium deposits of high purity... 

Among the oldest rocks on Earth are those on Isua, an island off the coast of Greenland they are 3.8 Gyr old, formed some 0.7 Gyr after accretion of the Earth. The rocks mark the beginning of the Archean period of geological time. The Isua rocks suggest that there was an extensive hydrosphere at this time, with erosion, transportation and deposition of minerals from water solution. The oldest lunar rocks, however, record an earlier high-temperature event - the Earth-Moon capture event. 

Butler, G.P., 1969, Modem evaporite deposition and geochemistry of coexisting brines, the sabkha, Trucial Coast, Arabian Gulf. Journal of Sedimentary Petrology 39,70-89. 

Sullivan, T.J. and M.C. Mix. 1985. Persistence and fate of polynuclear aromatic hydrocarbons deposited on slash burn sites in the Cascade Mountains and coast range of Oregon. Arch. Environ. Contam. Toxicol. 14 187-192. 

ABSTRACT The Mallik gas hydrate field represents an onshore permafrost-associated gas hydrate accumulation in the Mackenzie Delta on the coast of the Beaufort Sea, Northwest Territories, Canada. This deposit contains a high concentration of natural gas hydrate with an underlying aquifer or free-gas zone at the base of the hydrate stability field. The physical and chemical properties of CH4 and C02 hydrates indicate the possibility of coincident C02 sequestration and CH4 production from the Mallik gas hydrate bearing zones. This study presents a numerical assessment of C02 sequestration and the recovery of CH4 from the gas hydrates at the Mallik site, Mackenzie Delta, Canada. 

Majorowicz Osadetz (2001) reported that the Mallik gas hydrate-bearing deposit in permafrost regions tends to occur at depths of 700 m to 1400 m where the permafrost is 100 m to 900 m thick. The Mallik 2002 Gas Hydrate Production Research Well Program conducted scientifically constrained production tests of the natural gas from the Mallik gas hydrate deposit, which is situated in the Mackenzie Delta on the coast of the Beaufort Sea, Northwest Territories, Canada (Dallimore et al. 2005a Satoh et al. 2005). Gas hydrate production tests demonstrated the potential for possible commercial production. Japan intends to establish commercial production from gas hydrates within the time frame of conventional natural gas production from the Mackenzie Delta (Yonezawa 2003). 

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