Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
The Leading Edge Signup for GSW Email News
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
The Leading Edge; July 2000; v. 19; no. 7; p. 744-750; DOI: 10.1190/1.1438708
© 2000 Society of Exploration Geophysicists
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Okada, K.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Geophysical exploration at Hishikari gold mine, Kagoshima, Japan

Kazuya Okada

Sumitomo Metal Mining Co., Tokyo, Japan

Corresponding author: K. Okada, fax 81 3 3436 7997

The first 20% of the full text of this article appears below.

The Hishikari epithermal gold-silver deposit, one of the world's richest gold mines, is in northeastern Kagoshima on Kyushu Island, southwest of Japan (Figure 1). The area is characterized by volcanic activity, ranging from the active Sakurajima and Kirishima volcanoes to local hot springs.


Figure Removed (Available Only in the Full Text)
View larger version (22K):
[in this window]
[in a new window]
  		Figure 1. Location of Hishikari gold mine.

 
Although gold prospecting in the area dates from 1750, it formerly was intermittent and small scale. The major deposits currently being developed were not discovered until geophysical surveys were applied to the area. They played an important role in the 1981 discovery and subsequent development of the mine.

Regional geologic mapping and reconnaissance geophysical surveys were conducted by the Metal Mining Agency of Japan (MMAJ) in 1975–78. A gravity survey in 1975–76 revealed a northeast-trending gravity high (amplitude = 4 mGal). In 1976, electrical sounding using a Schlumberger array and a heliborne EM survey were carried out. Both detected a low-resistivity zone. Exploration drilling was carried out where the high-gravity anomaly overlapped the low-resistivity anomaly. All three holes intersected high-grade gold veins.

Subsequently, 18 more holes were drilled and carried out by Sumitomo Metal Mining (SMM), the property owner; all intersected high-grade ores. Underground development commenced in 1983. Between 1983 and 1987, SMM also tested various geophysical methods in the area to examine their potential application for exploration for this type of gold deposit. These included several methods not applied routinely to mineral exploration in Japan—MT, CSAMT, timedomain IP (TDIP), TEM, etc.


   Geology and ore deposit
 
The area is underlain by the Shimanto Supergroup of Cretaceous age and volcanic rocks/alluvial deposits of Quaternary age. Figure 2 shows geologic sections of the Honko and Yamada areas.


Figure Removed (Available Only in the Full Text)
View larger version (34K):
[in this window]
[in a new window]
  		Figure 2. Geologic cross-section for (a) Honko and Sanjin deposits and (b) Yamada deposit.

 
The Shimanto Supergroup, the basement rocks of the southern half of Kyushu Island, are interbedded shales and . . . [Full Text of this Article]






JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2009 by Society of Exploration Geophysicists