Boros István (szerk.): A Magyar Természettudományi Múzeum évkönyve 51. (Budapest 1959)
Kaszanitzky, F.: Genetic relation of ore occurrence in the Western Mátra Mountains, North Eastern Hungary
due to pyrite alteration, the rock contains no ore minerals. In its spatial extension this kind of andésite is related to the older hypovolcanitic choloro- and hydroandesites. The mode and age of its origin is unsolved as yet. In the author's opinion a smaller mass of magmatic melt, rich in vapors and gases, has diffused here across a kaolinitized andésite body covered by younger andésite, getting stuck below the unaltered andésite of the cover. The covering rock was subsequently eroded. The high-temperature melt has, as it were, fused the hydroandesite and the product has, further migration being impossible, cooled in the form of the mixed rock described above. The vorticity of the bubbles indicates rapid cooling. As kaolinization of greater extent is observed on older andésites, the rock plugging the above-described melt must have been the fine-grained inclusionrich pyroxene andésite. In this interpretation the formation of the bubbly andésite must have taken place some time before or simultaneously with that of the Mátra andésite. The bubbly rock type is in no connection with ore formation. The andésite types and their altered varieties constituting the area are tabulated below. Ore-productive hydrothermal veins came to exist in the last stage of andésite volcanism. They occur even in the lower parts of the young Mátra andésite hypovolcanites exometaendometa volcanites hypovolcanites volcanites forming fissure seams in tectonic zones IV. hypersthene, augite, hypersthenic augite andésites ("Mátra andésite" series) and agglomerates II. fine-grained inclusion-rich pyroxene andésite and agglomerate III. "bubbly" andésite (formed by acting of lava rich in volatiles upon older andésite (I)). hypovolcanic propylitization (chloroandesite) kaolinitization and silification (silicoandesite) o X y a n d e i t. e endometavolcanitic propylite (chloroandesite), bleaching (leucoandesite), kaolinitization (hydroandesitc), silification (silicohydrothermalite). carbonatization (carboandesite) pseudoagglomerates pseudotuffs I. b) biotitic hypersthene andésite, a ) andesit.es lacking melanocratic ingredients.
