High-resolution geochemical stratigraphy of Mauna Kea flows from the Hawaii Scientific Drilling Project core

Trace elements have been measured in the deepest 101 lava flows from the Hawaii Scientific Drilling Project (HSDP) by inductively coupled plasma mass spectrometry. In order to compensate for the lack of a precise timescale for the HSDP samples and in spite of some probable long stratigraphic hiatuses, a constant eruption rate is assumed that provides a timescale for the geochemical dynamics of Mauna Kea. Periods of nearly continuous variations in incompatible element ratios suggest that geochemical variability is controlled by reservoirs larger the shallow magma chambers inferred from seismicity and deflation data. The principal component analysis of the differenced data clearly separates three components associated with (1) olivine + spinel phenocryst abundance, (2) weathering, and (3) melting conditions and source mineralogy. The picritic character of some lavas does not seem associated with a particular mantle source or melting process. The weathering component appears to discriminate lateral from vertical transfer. A recurrence of the melting conditions or source heterogeneities on a scale time of similar to 30 kyr is inferred from the segmented record of incompatible element distributions.