The deposit of raw ceramic material at La crocetta, elba island, Italy

摘要

La Crocetta mine is an important producer of raw materials for the ceramic industry. The mined materials, called "eurite", are metasomatized porphyrytic alplites(8 Ma) of the Tertiary magmatic compplex of Elba Island. The "eurite" present setting, near to the Porto Azzurro monzogranitic stock (5.1-5.9 Ma), results from a 15 km ca eastward translation of the hosting flysch rocks from the original position on the top of Mt. Capanne monzogranite. The ore material results from pervasive sericitization of the protolith. A later alteration stage, controlled by N-S vertical tectonics, produced carbonate veining. Mass balance calculations indicate that sericitization was accompanied by loss of Na, Ca, Mg and Mn, and addition of K and Ba. Field and geochronological (~(40)Ar/~(39)Ar) data indicate that sericitization predates the emplacement of the Porto Azzurro stock and the N-S vertical tectonics, and is presumably related to fluid circulation along low-angle extensional faults.