Abstract

Massive Cu-Zn-Fe sulfide deposits appear to be replacements or syngenetic sediments related to submarine volcanism. Undisturbed kuroko deposits or moderately deformed and metamorphosed orebodies like those of the Noranda district may be considered as models.Massive sulfide deposits in high grade metavolcanic and metasedimentary rocks are postulated to have originated largely in a submarine volcanic environment near the edges of technically active troughs sinking and receiving clastic sediments. Adjacent rising segments eventually expose deep structures almost devoid of base metals. Massive sulfides and volcanics, together with enclosing sediments, are susceptible to transportation by slides and nappes. Thus ores and enclosing rocks may be moved several kilometers and effectively separated from former root structures such as alteration zones and hypabyssal intrusives. The Elizabeth massive sulfide deposits, Vermont thus appear to have moved westward from root zones near the Connecticut River prior to their metamorphism. Possibly some of the metamorphosed massive sulfide deposits of the Sanbagawa terrane, Shikoku, Japan have been transported southward from root zones near the Median Tectonic Line. After initial transposition by sliding, ores and host rocks may be subjected to deep burial, strong metamorphism and one or more episodes of folding.

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