Element mobility in paragneisses and metabasites of the Continental Deep Drilling Project (KTB/Germany)

Autor: W. Irber, U. Giese, P. Möller
Přispěvatelé: 4.3 Organic Geochemistry, 4.0 Chemistry and Material Cycles, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum
Rok vydání: 1997
Předmět:
Zdroj: Geologische Rundschau
Scopus-Elsevier
Popis: Leaching experiments (pH=3, T=70 °C) have been performed on paragneisses and metabasites from the KTB drill cores. The experiments yielded the fraction of total element content that is easily available to acidic aqueous fluids. The intensity of mineralogic alteration in the studied samples is expressed in terms of easily leachable fractions of K or Ba. Its reliability is shown by correlation with a petrographically determined alteration index. For the paragneisses, the easily available fractions of Fe, Mg, Mn, Ca, Na, K, Ba, Co, Cr, Ni, Sr, V, and Y together with the variables whole-rock content and depth of samples were subjected to a factor analysis, the results of which are presented as a five-factor model. Correlation plots of easily leachable element fraction and whole-rock content vs an alteration index (percentage of leachable K) reveal the changes in leachability as a function of intensity of alteration. In a cataclastic boundary between paragneisses and metabasites at 1610 m depth, the changes in whole-rock content and leachability of elements are studied in detail and compared with the general trends in alteration. The results point to considerable intercrystalline element redistribution during retrograde metamorphism, with only insignificant element transport on a meter scale. Although considerable fractions of many elements were easily available to acidic fluids (3
Databáze: OpenAIRE
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