Geochemical Indicators in the Hydrothermal Fluids for Exploration of Overprinting Orebodies

2022 Fiscal Year Research-status Report

• Project/Area Number: 22K14633
• Research Institution: Akita University
• Principal Investigator: Manalo Pearlyn 秋田大学, 国際資源学研究科, 助教 (50895480)
• Project Period (FY): 2022-04-01 – 2025-03-31
• Keywords: fluid inclusions / mineral chemistry / enargite / quartz

Outline of Annual Research Achievements

Fieldwork has been carried out in the Philippines to collect samples of porphyry and epithermal orebodies. Thin and thick sections of rock samples have been prepared for petrographic, fluid inclusions studies and electron probe microanalysis. A new optical microscope has been procured using this project and was used for petrographic observations. Mineral chemistry of enargite, the main ore mineral in the epithermal orebody, has been determined using the electron probe microanalyzer (EPMA). Bulk chemical composition of fluid inclusions in quartz and enargite has also been analyzed with the contribution of the collaborators. The internal structure of enargite have been successfully observed using an infrared camera. Phase transitions of fluid inclusions under infrared light observation have also been successfully documented, although a few data on the homogenization temperature and salinity of enargite-hosted fluid inclusions have been gathered. Observations on the relationships between the mineral chemistry of enargite, the chemistry of fluid inclusions and temperatures of formation are currently being summarized. Abstracts for conference presentations have been submitted and a manuscript about an orebody is currently being prepared.

Current Status of Research Progress

3: Progress in research has been slightly delayed.

Reason

Due to the delay in the procurement of gases necessary to operate the laser ablation machine, the LA-ICPMS analysis has not yet been carried out. Some commercial laboratories have changed operation conditions due to the pandemic, so some laboratory analyses are delayed.

Strategy for Future Research Activity

Laboratory analysis including fluid inclusion and mineral chemistry analysis will be continued to get significant amount of data. Petrography and XRD analyses of rock samples on overprinting epithermal high-sulfidation and porphyry-type systems would be carried out this year. Samples for isotopic analyses will be sent to Canada and New Zealand to determine the source of ore-forming fluids.

Causes of Carryover

Some of the isotopic analyses has been delayed and will be carried out in the 2023 fiscal year.

Research Products

• [Presentation] Ore mineral chemistry and fluid composition of the Florence Orebody, Lepanto Mine, Mankayan District, Northern Luzon, Philippines (2023)
  • Author(s): Ryota Mine, Pearlyn Manalo, Ryohei Takahashi, Nigel Blamey, Andrea Agangi, Hinako Sato, Akira Imai, Leo Subang, Mervin de los Santos, Rhyza Ruth Parcon-Calamohoy, Glenn Alburo
  • Organizer: Japan Geoscience Union Meeting 2023
  • Int'l Joint Research
• [Presentation] Characteristics of two different high-sulfidation veins in the Florence orebody, Lepanto Mine, Mankayan District, Philippines (2022)
  • Author(s): Ryota Mine, Pearlyn Manalo, Ryohei Takahashi, Andrea Agangi, Hinako Sato, Akira Imai, Rhyza Ruth Parcon-Calamohoy, Glenn Alburo, Leo Subang, Mervin de los Santos
  • Organizer: GEOCON 2022: Disruptions, Transformations - Geosciences at the Forefront