Kaolinization


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kaolinization

[‚kā·ə·lə·nə′zā·shən]
(geology)
The forming of kaolin by the weathering of aluminum silicate minerals or other clay minerals.

Kaolinization

 

rock alteration leading to the formation of kaolin by the transformation of various minerals containing alumina, and, above all, of feldspars and mica. Kaolinization is most strongly manifested in the formation of a kaolin weathering mantle as a result of weathering in granites, syenites, and other feldspathic rock, evidently under humid, subtropical conditions. In this process a finely flaked, alumina-rich mica is initially formed from the feldspar. This mica is called sericite, and subsequently it becomes hydrated and is converted into hydromica and kaolinite. Remnants of hydromica are often present among the kaolinites that have formed as a result of kaolinization. Kaolinization processes are also manifested when there is perisurface hydrothermal alteration of rock in areas of volcanic activity.

Intensive processes of rock kaolinization and the formation ofweathering mantles occurred during the Carboniferous, Jurassic, Paleogene, and Neocene periods, which were characterized byabundant vegetation and a relatively humid and warm climate. Modern kaolinization is most characteristic in the humid tropics.

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References in periodicals archive ?
Incomplete kaolinization indicates lesser amount of kaolin minerals, and thus lowers Al2O3 content (Sayin, 2007; Visser and Young, 1990).
d) kaolinite sample from Znojmo region, formed by kaolinization of granitoid rocks (Unanov locality)
1981, The products arisen from acid plagioclase and potassium feldspar during the kaolinization of Karlovy Vary granite.
1972, Changes of primary biotite and muscovite during kaolinization of granites, Carlsbad area, Czechoslovakia.
1969): Comparison of the proofs of hydrothermal and supergene kaolinization in two areas of Europe.
1972): Changes of primary biotite and muscovite during kaolinization of granites, Carlsbad area, Czechoslovakia (Zmeny primarniho biotitu a muskovitu behem kaolinizace zul, Karlovarsko, Ceskoslovensko).
In most of the best deposits, intense kaolinization of the feldspars and abundant lithium mineralization is common.
The highly intruded condition of the hanging wall has resulted in extensive kaolinization which has widened the mineralized vein to a total thickness of 10 feet in some places (Pratt, 1938).
The climatic weathering hypothesis received support from Vachtl and Zemlicka (1959), while Kavka (1977, 1978) prefers kaolinization caused by the volcanothermal interaction between hot phonolite lava and wet lacustrine sediments.
The dikes have undergone extensive hydrothermal alteration, typified by sericitization, kaolinization and pyritization.
2000, D-H evidence for the timing of kaolinization in Northeast Bavaria, Germany, Chemical Geology, 170, 5-18.