1979 Volume 29 Issue 155 Pages 147-159
Pyrometasomatic lead and zinc deposits in the Nakatatsu mine are localized in skarn masses consisting of clinopyroxene (hedenbergite) and garnet. The data obtained through recent exploration works and the various data accumultated for several decades were critically studied for elucidating the geological and mineralogical features controlling the localization of ores. The results are as follows: (1) Ore/skarn ratio is much higher in the clinopyroxene skarn zone than in the garnet skarn zone. (2) The clinopyroxene skarn zone with high ore/skarn ratio is located in the hanging wall side of the Nakayama skarn zone below -200 m Level. (3) ρPb, which is defined here as 10Pb%÷(10Pb%+Zn%)×100, is distributed in each orebody in a zonal fashion with higher value at the central part of the orebody and lower at the margin. (4) The areas of the ρPb ranging from 20 to 40 are favourable sites for high grade and large scale orebodies in this mine. (5) Orebodies are often associated with the folded structure in the clinopyroxene skarn zone surrounding non-skarnized limestones.
These indicators were employed as guides in prospecting works and two high-grade orebodies were found below the -200m level down to the present lowest level (-360m) of the mine.
