現場担当者会議講演論文
ペルー共和国パルカ鉱山の最近の探鉱成果
2013 年 63 巻 2 号 p. 51-68
詳細
2013 年 63 巻 2 号 p. 51-68
The Pallca mine in the Peruvian Andes has been producing lead-zinc ore since 2006. Then, intensive exploration and development activities have been carried out on deposits of the Berlin zone located in the east side of the Culebra complex (acidic intrusives). Through accumulation of results of geological investigation on the Berlin zone, following facts were revealed;
1. The mineralization is closely related to the V3 Upper Fault (Gomi Fault) and fold structure of the Santa Formation (Limestone). Also, quartz porphyry stocks and sheets always occur closely to skarn and mineralization.
2. On the basis of their mode of occurrence and mineral assemblage, ore genesis are divided into the following two stages; (1) early mineralization stage and (2) late hydrothermal mineralization stage.
3. According to analysis on distribution of skarnization and mineralization, the mineralization occurs intensively in the Carhuaz Formation (Shale, sandstone, limestone) rather than the Santa Formation in the southern part of the Berlin zone.
Based on the results of those analyses, the exploration program emphasized on the Carhuaz Formation in the south part Berlin zone made discoveries of large deposits in the Carhuaz Formation.
In addition, we measured the homogenization temperature of fluid inclusions and EPMA quantitative analysis of skarn ore in the Berlin zone. As a result, it was found to exhibit a similar trend of change in each line and in calcite and clinopyroxene Fe content of sphalerite. it is considered that the ore-forming fluid has been moved from the side or deep of intrusive rocks.
