STUDY OF THE WALL ROCK ALTERATION OCCURRING IN ULTRAM A F I C ROCKS HOSTING MAGNESITE DEPOSITS, EVIA, GREECE,

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Published: Jan 1, 2004
DOI: https://doi.org/10.12681/bgsg.16688
Κ. Σερέλης
Division of Geological Sciences and Atmospheric Environment, Dept. of Sciences, Agricultural University of Athens
Ε. Γκάρτζος
Division of Geological Sciences and Atmospheric Environment, Dept. of Sciences, Agricultural University of Athens
Π. Τσαουσίδου
Division of Geological Sciences and Atmospheric Environment, Dept. of Sciences, Agricultural University of Athens
Abstract

Three different kinds of alteration processes occur in the studied ultramafic host rocks of the magnesite deposits of N. Evia. In chronological order: Pre-magnesite event (serpentinization), syngenetic brown alteration and weathering. This paper concerns the syngenetic wall rock alteration of the ultramafic host rocks. Two types of wall rock alteration were distinguished. The first one named type (B-i) concerns cases of brown alteration accompanying thin to medium size veins of magnesite. Alteration is restricted in thin (a few cm to 20 cm) vein-parallel bands occurring on both sides of the vein. Alteration increases gradually towards the edges of the vein. The altered band consists mainly of abundant dolomite and/or quartz. The second type (B2) concerns argillic alteration of large ultramafic masses in areas with intense magnesite mineralization and can be observed along the walls of the open pit mines. Secondary vermiculite has been formed in this case. Both types are related to the genesis of the magnesite deposits

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  • Economic Geology
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