Abstract

Based on a study of minor occurrences of zinc, barite, and iron in East Tennessee, certain deposits are interpreted to have formed during early Middle Ordovician time. Principal lines of evidence supporting this age are: (1) the occurrence of barite, sphalerite, and pyrite associated with synsedimentary collapse breccias which span the pre-Middle Ordovician unconformity at the Lost Creek barite mine in Union County; (2) barite in basal Middle Ordovician beds (Athens Shale and Lenoir Limestone) in northeastern Tennessee and southwestern Virginia; (3) sphalerite and pyrite in dolomite filling paleocaves in the uppermost part of the Lower Ordovician Mascot Dolomite at the Trotter prospect near Douglas Dam in Sevier County; and (4) oolitic hematite and pyritiferous beds near the base of the Athens Shale and subjacent pyritiferous collapse breccias in the Mascot and Kingsport Formations at several localities along the eastern side of the Appalachian Valley. Thus, it is concluded that ascending solutions formed epigenetic deposits in pre-Middle Ordovician carbonate strata nearly contemporaneously with syngenetic deposits in early Middle Ordovician sediments.These findings are in general accord with those of recent workers in the Mascot-Jefferson City and Copper Ridge districts who have proposed that mineralization in these areas occurred during the time interval of pre-Middle Ordovician erosion. The long-held theory which associates mineralization with late Paleozoic diastrophism is not supported.

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