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Practical Application of Low Na2O Anomalies in Footwall Acid Lava for Delimiting Promising Areas around the Kosaka and Fukazawa Kuroko Deposits, Akita Prefecture, Japan

By
Hironori Hashiguchi
Hironori Hashiguchi
Hanaoka Mine, Dowa Mining Company, 017-01 Hanaoka-cho, Odate-shi, Akita Prefecture, Japan
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Ryoichi Yamada
Ryoichi Yamada
Hanaoka Mine, Dowa Mining Company, 017-01 Hanaoka-cho, Odate-shi, Akita Prefecture, Japan
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Tsuneshi Inoue
Tsuneshi Inoue
Hanaoka Mine, Dowa Mining Company, 017-01 Hanaoka-cho, Odate-shi, Akita Prefecture, Japan
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Published:
January 01, 1983

Abstract

The variation of Na 2 O in the acid lava underlying Kuroko deposits has been examined as a convenient exploration guide. First, the precise spatial distribution of the low Na 2 O anomaly around certain Kuroko deposits was established using a large number of samples collected systematically from the footwall acid lava. Then the applicability of using the anomaly for delimiting promising areas around the Kosaka and the Fukazawa deposits was examined. The following results have been obtained. 1. The most economical threshold can be set at 0.36 percent Na 2 O in the Kosaka area and 0.32 percent Na 2 O in the Fukazawa area. The small difference in the Na 2 O value of the thresholds is compatible with previous results. 2. The areal distribution of the low Na 2 O anomaly, however, is somewhat different in extent and shape from that presented previously. The difference in distribution is probably due to a different interpretation of high Na 2 O masses near the footwall of orebodies; namely, they are. regarded as either unaltered remnants or as intrusions. 3. The general areal extent of the anomaly in this study is two or three times as large as the presently known extent of ore and has a high correlation with small offsets of ore distribution. The variation of Na 2 O in the footwall is particularly useful for detailed exploration, but the extent may be too small for regional explorations.

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Economic Geology Monograph Series

The Kuroko and Related Volcanogenic Massive Sulfide Deposits

Hiroshi Ohmoto
Hiroshi Ohmoto
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Brian J. Skinner
Brian J. Skinner
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Society of Economic Geologists
Volume
5
ISBN electronic:
9781629490007
Publication date:
January 01, 1983

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