Crust chemical composition

The presence of tubercles is usually obvious. Friable brown and orange nodular encrustations on mild steel and cast iron cooling water components are almost always tubercles (Figs. 3.12 through 3.14). The presence of a crust, shell, core, cavity, and corroded floor are definitive (Fig. 3.3). Careful analysis can provide considerable information concerning growth, chemical composition, and associated metal loss. 

Explain why a line graph might not be appropriate to show the chemical composition of Earth s crust. 

The planets nearest the Sun have a high-temperature surface while those further away have a low temperature. The temperature depends on the closeness to the Sun, but it also depends on the chemical composition and zone structures of the individual planets and their sizes. In this respect Earth is a somewhat peculiar planet, we do not know whether it is unique or not in that its core has remained very hot, mainly due to gravitic compression and radioactive decay of some unstable isotopes, and loss of core heat has been restricted by a poorly conducting mainly oxide mantle. This heat still contributes very considerably to the overall temperature of the Earth s surface. The hot core, some of it solid, is composed of metals, mainly iron, while the mantle is largely of molten oxidic rocks until the thin surface of solid rocks of many different compositions, such as silicates, sulfides and carbonates, occurs. This is usually called the crust, below the oceans, and forms the continents of today. Water and the atmosphere are reached in further outward succession. We shall describe the relevant chemistry in more detail later here, we are concerned first with the temperature gradient from the interior to the surface (Figure 1.2). The Earth s surface, i.e. the crust, the sea and the atmosphere, is of... 

Yan, M.C. Chi, Q.H. 1997. The Chemical Compositions of Crust and Rocks in the Eastern Part of China. Beijing Science Press, 292p (in Chinese with an English preface). 

Coleman ML (1971) Potassium-calcium dates from pegmatitic micas. Earth Planet Sci Lett 12 399-405 Condie KC (1993) Chemical composition and evolution of the upper continental crust contrasting results from surface samples and shales. Chem Geol 104 1-37... 

Many asteroids are dry, as evidenced by meteorites in which water is virtually absent. These samples include many classes of chondrites, as well as melted chunks of the crusts, mantles, and cores of differentiated objects. Anhydrous bodies were important building blocks of the rocky terrestrial planets, and their chemical compositions reveal details of processes that occurred within our own planet on a larger scale. The distributions of these asteroids within the solar system also provide insights into their formation and evolution. 

How does the chemical composition of the Martian crust differ from that of the Moon ... 

The formation of the terrestrial planets is constrained by their bulk chemical compositions, but determining the compositions of entire planets is challenging. Because planets are differentiated into crust, mantle, and core, there is no place on or within a planet that has the composition of the entire body. Before considering the formation of the terrestrial planets, let s review how we go about estimating their bulk compositions. 

Some estimates of the bulk chemical compositions of the other terrestrial planets are compared with the Earth s in Table 14.2. In this compilation, the compositions and relative proportions of the silicate (mantle plus crust) and core fractions are separated. 

Plank T, Langmuir CH (1998) The chemical composition of subducting sediment and its consequences for the crust and mantle. Chem Geol 145 325-394... 

The part of Earth s geosphere that is accessible to humans is the crust, which, ranging from 5 to 40 km in thickness, is extremely thin compared to the diameter of the earth. Most of the solid earth crust consists of rocks. Rocks are composed of minerals, where a mineral is a naturally occurring inorganic solid with a definite internal crystal structure and chemical composition. A rock is a solid, cohesive mass of pure mineral or an aggregate of two or more minerals. 

The materials that make up the earth s crust are described at two levels. The smallest unit of classification is the mineral, which is defined as a natural, homogeneous inorganic solid having a definite chemical composition and a crystalline structure. The second, more complex classification unit is the rock, which is defined as any natural solid made up of one or more minerals. 

Holland, I. G., Lambert, R. St. J. Major element chemical composition of shields and the continental crust. Geochim. et Cosmochim. Acta 36, 673-683 (1972). 

Next to aluminium, iron is the most abundant and widely distributed metal in the crust of the earth.1 It is seldom found free in nature owing to the extreme readiness with which it combines with moist air to form the hydrated oxide known as rust. Such ferruginous minerals as contain a sufficiently high percentage of iron, possess a suitable chemical composition, and occur in nature in large quantity, are termed ores and are used for the commercial extraction of iron. Owing to their economic importance the ores of iron have been studied with unusual care, and the suitability of the more important types for metallurgical purposes is discussed in Part III. of this volume. 

Rankama, K., 1957. Geological data on the chemical composition of the Precambrian atmosphere. In Zemnaya kora (Crust of the Earth). Izd. IL, Moscow, pp. 672-686 (in Russian). 

Ronov, A.B. and Yarochevskiy, A.A., 1971. The chemical composition of the Earth s crust. In Svyaz poverkhnostnykh struktur zemnoy kory s glubinnymi (Relationship of Surface and Deep-Seated Structures of the Earth s Crust). Izd. Naukova Dumka, Kiev, pp. 192-207 (in Russian). 

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