:The Na2O anomaly in the footwall acid lavas

概要

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Previous studies of geochemical prospecting in the Hokuroku region have revealed that acid lavas underlying kuroko deposits are in general significantly depleted in Na 2O in comparison with those on which no kuroko deposits exist. The Na 2O content of the footwall acid lavas may thus provide a practical geochemical indicator which enables us to delimit a promising area for prospecting around the known kuroko deposits. The Na 2O variation in the footwall acid lavas has extensively been examined in the vicinity of the Uchinotai-Uwamuki deposits, Kosaka mine and of the Fukazawa deposits, Hanaoka mine. The following results have been obtained: 1) The most economical threshold to delimit the promising area can be set at Na 2O = 0.36 wt% in the Uchinotai-Uwamuki area and at Na 2O = 0.32 wt% in the Fukazawa area. 2) The promising areas thus defined are two or three times as large as the presently known extents of these deposits. 3) Some new orebodies have successfully been discoverd by this method.
資源地質学会の論文