著者

麻木 孝郎 末岡 慎也 深澤 秀明 伊東 靖彦 古野 正憲 長 久

出版者

The Society of Resource Geology

雑誌

資源地質 (ISSN:09182454)

巻号頁・発行日

vol.54, no.1, pp.27-36, 2004-05-20 (Released:2009-06-12)

参考文献数

5

被引用文献数

1

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Since 2001, Nittetsu Mining has been carrying out copper exploration activities in twenty-two promising areas in Northern Chile, which were extracted using ASTER image analysis. In these areas, Furano area in Region I has been selected as the most important target considering its high mineral potential inferred from the ASTER image analysis and its easy access.Furano area, covering 282km2, locates some 15km northwest of Cerro Colorado copper mine. Geology of the basement rocks mainly consists of lower Cretaceous andesite and Paleogene intrusive rocks. They are widely covered by ignimbrite and alluvium sediment of Tertiary to Quaternary age. The RC drilling program of 13 holes, totaling 3, 704m, was carried out on the prospective locations in the western part of the project area, which were selected by geological and geochemical surveys. Dominant copper and gold mineralizations were observed in some holes. Above all, a tourmaline breccia zone in silicified andesite showed average copper grade of 0.9% over the depth from 110m to 190m in one hole. The ore body shows 40m in width, dipping 55 degrees towards north, and is expected to be 400m continuation from the distribution of surface mineral occurrences. About 20 million tons of ore reserve was estimated above the depth of 300m. In another hole, drilled in ignimbrite-covered area, oxidized and corroded tourmaline breccia and underlying chalcopyrite-disseminated granite porphyry were observed. A secondary precipitation of chalcocite was also recognized in the lower part of the tourmaline breccia. These evidences suggest that the adjoining area covered by ignimbrite still has high potential for porphyry copper deposition. Additional drilling exploration is required around those holes.