Hydrothermal Activity Events at Kairei Field, Central Indian Ridge 25°S

Abstract

AbstractThe Kairei hydrothermal field is located on the Central Indian Ridge at 70°02′E, 25°19'S, which was discovered in 2000. Eight representative hydrothermal product samples including massive sulfide, sulfide chimney and mineralized rock breccia samples collected from this field were age‐dated using the 230Th/234U and 210Pb/Pb methods. Four episodes of hydrothermal activity were determined: 94.5 to 96.3 ka (event I), 56.6 to 61.2 ka (event II), 8.4 to 10.6 ka (event III), and <180 a to present (event IV). Among them, event I is the oldest and is characterized by the low‐temperature mineralization of rock breccias which probably represents for the onset of the hydrothermal activity of the field. Events II to IV represent the episodic high‐temperature hydrothermal activities characterized by Cu and Zn‐rich sulfides. The recent hydrothermal activity has lasted for at least 180 a.