Potassium isotopic composition of low-temperature altered oceanic crust and its impact on the global K cycle

Abstract To constrain the behavior of K isotopes during the low-temperature alteration of oceanic crust and reveal its impact on the global K cycle, we measured the K isotopic compositions of 49 fresh and altered basalts recovered from the Integrated Ocean Drilling Program (IODP) Sites U1365 (~100 Ma) and U1368 (~13.5 Ma) in the South Pacific Ocean. The measured basalts representing the uppermost oceanic crust have been subjected to low-temperature (