Minerals metamorphic rocks

Most igneous and metamorphic rocks are composed predominantly of alurninosiHcate minerals, including feldspar such as albite (NaAlSi Og) or anorthite (CaAl2Si20g) and crystalline forms of siHca such as quartz (Si02). Various mixed metal-plus-siHcon oxides such as oHvine [(Mg,Fe)2(SiO ] and... 

Slate. A dense fine-grained metamorphic rock containing mainly clay minerals. 

Soil water flow is decidedly episodic. During dry times the water solutions in the soil are probably fairly concentrated and not very reactive. Time-averaged reaction rates should be roughly proportional to the fraction of time reacting minerals are in contact with thermodynamically imdersaturated (and reactive) water. In a study of the relationship between denudation rate and runoff for rivers draining igneous and metamorphic rock in Kenya, Dunne (1978) obtains the relationship of (denudation rate in tons/km per year) = 0.28 (runoff in mm/ year)°. ... 

Feldspars are the most abundant minerals of igneous and metamorphic rocks 0 2). Being the most abundant rock-forming minerals of the earth s crust, they have received a proportionately large share of attention from students of weathering, and most of the major analytical advances and conceptual models which have been applied to other mineral groups have also been applied to feldspars. 

Graham CM (1981) Experimental hydrogen isotope studies. Diffusion of hydrogen in hydrous minerals, and stable isotope exchange in metamorphic rocks. Contrib Mineral Petrol 76 216-228 Hoefs J (2004) Stable isotope geochemistry. S" Edition. Springer, Berlin... 

Figure 1. Stable-chlorine isotopic composition of meteorites, igneous and metamorphic rocks and minerals reported as 8 Cl relative to Cl/ Cl in Standard Mean Ocean Chloride (SMOC) represented by die vertical dashed line at 0 %o. Data from Magenheim et al. (1994), Magenheim et al. (1995), Bridges et al. (2001), Eggenkamp and Koster van Groos (1997), Boudreau et al. (1997), Willmore et al. (2002), Musashi et al. (1998), Markl et al. (1997), Eggenkamp and Schuiling(1995). Filled symbols are E-MORB and gray boxes represent preliminary data of E-MORB from Stewart (2000).

Cl Isotope Compositions of Natural Anthropogenic Materials 235 Igneous and metamorphic rocks and minerals... 

The sedimentary and metamorphic rocks uplifted onto land have become part of continents or oceanic islands. These rocks are now subject to chemical weathering. The dissolved and particulate weathering products are transported back to the ocean by river runoff. Once in the ocean, the weathering products are available for removal back into a marine sedimentary reservoir. At present, most mass flows on this planet involve transport of the secondary (recycled) materials rather than the chemical reworking of the primary (juvenile) minerals and gases. The natirre of these transport and sediment formation processes has been covered in Chapters 14 through 19 from the perspective of the secondary minerals formed. We now reconsider these processes from the perspective of impacts on elemental segregation between the reservoirs of the crustal-ocean-atmosphere factory and the mantle. 

Raheim A. (1975). Mineral zoning as a record of P, T history of Precambrian metamorphic rocks in W. Tasmania. Lithos, 8 221-236. 

A critical issue is the extent to which the isotope composition of a metamorphic rock is modified by a fluid phase. Volatilization reactions leave an isotope signature greatly different from that produced when fluid-rock interaction accompanies mineral-fluid reaction. Changes of 5-10%c are a strong indication that fluid-rock interaction rather than volatilization reactions occurred during the metamorphic event. Coupled 0-C depletions are seen in many metamorphic systems involving carbonate rocks. Figure 3.50 summarizes results from 28 studies of marble mostly... 

EUer JM, VaUey JW, Graham CM, Baumgartner LP (1995) Ion microprobe evidence for the mechanisms of stable isotope retrogression in high-grade metamorphic rocks. Contr Miner Petrol 118 365-378... 

Taylor HP, Epstein S (1962) Relation between 0/ 0 ratios in coexisting minerals of igneous and metamorphic rocks, I Principles and experimental results. Geol Soc Am Bull 73 461 80 Taylor HP, Forester RW (1979) An oxygen and hydrogen isotope study of the Skaergaard intrusion and its country rocks a description of a 55 M.Y, old fossil hydrothermal system. J Petrol 20 355 19... 

Valley JW (1986) Stable isotope geochemistry of metamorphic rocks. Rev Miner 16 445 89 Valley JW (2001) Stable isotope thermometry at high temperatures. Rev Miner Geochem 43 365 13... 

Frost, B.R. Lindsley, D.H. (1991) Occurrence of iron-titanium oxides in igneous rocks. In Lindsley, D.H. (ed.) Oxide minerals. Reviews in Mineralogy 25, Min. Soc. Am., 433-468 Frost, B.R. (1991) Stability of oxide minerals in metamorphic rocks. In Lindsley, D.H. (ed.) Oxide minerals. Reviews in Mineralogy 25, Min. Soc. Am., 469-488 Fryer, J.R. (1979) The chemical applications of transmission electron microscopy. Academic Press, London New York, 231 p. 

Therefore, to kineticists and informed geochronologists, the age obtain from an isochron equation or from Example 1-5 is an apparent age, and is called the closure age (Dodson, 1973) because it means the age since the closure of the mineral, not necessarily since the formation of the mineral. The closure age may differ from the true age or formation age because of diffusive loss (or exchange) of the daughter nuclide. For the closure age to be the same as the formation age, the mineral must have cooled down rapidly (for volcanic rocks) or formed at not-so-high a temperature (for metamorphic rocks) so that diffusive loss from the mineral is negligible. 

Zircon (ZrSi04) is a common accessory mineral in igneous and metamorphic rocks. It can take a significant amount of U in its structure (in the Zr site) at the thousands of ppm level, but takes very little original Pb. Because there is an unradiogenic stable isotope of Pb ( °" Pb), the very minor amount of initial ° Pb and ° Pb may be roughly corrected by assuming reasonable initial ratios of ° Pb/ °" Pb and ° Pb/ ° Pb (based on the evolution of these ratios with time in the Earth). Two U isotopes decay to two Pb isotopes decays to Pb, and... 

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