Structure and Mineralization at the Nakatatsu Mine, with Special Emphasis on the Folding Structure and Structural Control of the Nakayama Ore Deposits

Abstract

Pyrometasomatic lead and zinc deposits at the Nakatatsu mine, occur in skarn masses of the Paleozoic limestone. Regarding the geologic structure and mineralization of the ore deposits, the following features have been clarified;
1) The E-W trend faults, which are the most fundamental structure in the regional scale, are characterized by a vertical movement.
2) The N-S trend faults, which are characterized by a horizontal movement, have the character of echelon faults and have been related to the mineralization closely.
3) In the limestone beds, which show general trend of E-W to N 50°E and which are the host rocks of ore deposits, the folding structure of reverse Ω shape have been recognized. The plunge of the folding structure is 45°-50°to S 20°W. Ore deposits of the mine is strongly controlled by this geological structure.
4) Many ore deposits are localized in the hedenbergite skarn zone in the outer periphery of garnet skarn zone.
Based upon the above features, the relation, between the ore deposition and the geological structure have been verified, and consequently the exploration works have been carried out effectively.