Study on formation mechanism of submarine native copper deposits based on copper isotopic measurement

2015 Fiscal Year Final Research Report

• Project/Area Number: 26800271
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: University of Tsukuba
• Principal Investigator: IKEHATA Kei 筑波大学, 生命環境系, 助教 (70622017)
• Research Collaborator: HIRATA Takafumi 京都大学, 大学院理学研究科, 教授 (10251612)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 自然銅 / 熱水鉱物 / 銅同位体比 / 火山岩

Outline of Final Research Achievements

Hydrothermal native copper occurred in alkali basalt of ancient seamount from Boso Peninsula, Chiba, Japan. The native copper was precipitated from relatively low-temperature neutral to alkaline hydrothermal fluid under sulfur-poor conditions. Occurrence and chemical composition of the native copper are similar to those from Michigan, USA. Hydrothermal native copper is well known to occur in mid-ocean ridge and continental tholeiitic basalts, but this is the first description of an occurrence in ocean island alkali basalt. Most of the hydrothermal native coppers have slightly higher copper isotope values than terrestrial igneous copper which is the probable source. This suggests the native coppers were formed as a result of relatively low-temperature hydrothermal activity in the host rocks.

Free Research Field

岩石学、鉱床学、地球化学