Unspiked K–Ar dating of Pleistocene tholeiitic basalts from the deep core SOH-4, Kilauea, Hawaii

Tholeiitic subaerial lava flows from Kilauea (SOH-4 deep core) were successfully dated by unspiked K–Ar with 40Ar * contents as low as ≈0.1%. Ages between 436 and 42 ka were found on lavas between the depths of 1650 and 468 m. All subaerial ages are consistent with their stratigraphic position and allow us to derive a lava accumulation rate of 3.07±0.44 mm/a, which is within the range of rates determined in high 40Ar * OIBs. Age determinations on dike samples yield ages that are younger than those of the enclosing lavas. The validity of the ages was cross-checked with U-series ages of coral terraces on the northwest flank of Hawaii as determined by Ludwig et al. (1991). Dating problems seem to be restricted to a submarine pillow lava sample from level 1808 m, which gives an apparent age of ≈1 Ma, which is an overestimate with respect both to rate of construction of Kilauea and the Hawaiian plume history.