Earth oceanic crust, formation

The seventh element in order of abundance in the Earth s crust is potassium - about the same as sfjdium with similar properties. While sodium is readily available from the ocean, potassium is found and extracted from many mineral formations. About 90 percent of the potassium that is extracted goes to the production of fertilizers. Other purposes for it are ceramics and fire extinguishers for which potassium bicarbonate is better than sodium bicarbonate. 

Typical BIF are characteristic only of the Precambrian, and the regularities of their formation should be considered in connection with the geochemical evolution of the conditions of sedimentation, atmosphere, ocean, and life in the early stages of development of the Earth s crust. 

Petroleum formed from the remains of microorganisms that lived in Earth s oceans millions of years ago. Over time, the remains formed thick layers of mudMke deposits on the ocean bottom. Heat from Earth s interior and the tremendous pressure of overlying sediments transformed this mud into oil-rich shale and natural gas. In certain kinds of geological formations, the petroleum ran out of the shale and collected in pools deep in Earth s crust. Natural gas, which formed at the same time and in the same way as petroleum, is usually found with petroleum deposits. Natural gas is composed primarily of methane, but it also has small amounts of alkanes having two to five carbon atoms. 

Many carbonate minerals are found in the earth s crust. As a result, the waters of several lakes, rivers, and even oceans are in contact with these minerals. CaC03 is the primary component of limestone and marble, while dolomite (CaMg(C03)2) and magnesite (MgC03) are minerals found in other rock formations. 

If, as many suppose, the Archaean mantle had a higher potential temperature than the modern mantle, it is important to examine the implications of this for melt production during the early history of the Earth. The relationship between mantle potential temperature and melt thickness during adiabatic melting was outlined in Section 3.1.4.3 and may be briefly summarized by stating that as mantle potential temperature increases so will the melt production, as expressed in the depth of the melt column and the melt thickness. This is illustrated in Fig. 3.26, which shows how deeper, higher-temperature melting should lead to the formation of a thicker oceanic crust. 

Movement of the relatively high concentration of copper from the Earth s crust into the soil depends on weathering, the process of the soil s formation, drainage, oxidation-reduction potential, the amount of organic matter in the soil, and the pH. Copper is concentrated in the clay mineral fractions rich in organic carbon. Almost all of the copper carried into the ocean is precipitated accounting for its lower concentration there than in fresh water. 

D ecent development of our knowledge of lanthanide distributions in nature encouraged us to believe that variations in ratios of these elements might well characterize individual water masses as summarized by Haskin et al. (5), considerable lanthanide fractionation has occurred in the formation of the earth s crust it might be expected that these fractionations would be reflected in the lanthanide patterns of material eroded from diflFerent regions and supplied to the oceans. Since, on the other hand, the lanthanide patterns of marine shales and sediments (5, 6, 11) do not reflect these regional diflFerences but are essentially uniform on a world-wide basis, sea water should express the diflFerential residues on a... 

Radon is a product of the natural radioactive decay of uranium, which occurs naturally in the earth s crust, to radium and then to radon. As radium decays, radon is formed and is released into small air or water-containing pores between soil and rock particles. If this occurs near the soil surface, the radon may be released to ambient air. Radon may also be released into groundwater. If this groundwater reaches the surface, most of the radon gas will quickly be released to ambient air, but small amounts may remain in the water. By far, the major source of radon is its formation in and release from soil and groundwater, with soil contributing the greater amount. Smaller amounts of radon are released from the near surface water of oceans, tailings from mines (particularly uranium... 

During the formation of the Earth, 4.65 billion years ago, along with the stable nuclides, several radionuclides were formed. Those that were radioactive with a half-life too short with respect to the formation of the Earth obviously disappeared. On the other hand, those with half-lives of the same order of magnitude or greater than that of the formation of Earth are mainly responsible for the natural radioactivity of the Earth s crust materials (i.e., ice, river, sea and ocean waters, minerals, ores, rocks, and soils). Today, over 60 radionuclides occur in the environment, and they can be grouped into three main categories ... 

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