Geochemical stratigraphy of lava flows sampled by the Hawaii Scientific Drilling Project

Author:

Rhodes, J.M.

Title:

Geochemical stratigraphy of lava flows sampled by the Hawaii Scientific Drilling Project

Periodical:

Journal of Geophysical Research

Year:

1996

Volume:

101

Pages:

11,729-11,746

Subject:

Hawaii Scientific Drilling Project Trace elements Geochemistry Lava analysis

Summary:

This paper reports major and trace element whole rock analyses of 94 individual flow units sampled by the Hawaii Scientific Drilling Project. The upper 280m of the core consists of tholeiitic Mauna Loa flows. The 60m-thick zone between 280m and 340m consists of alkalic basalts and tholeiites that correlate with the postshield Hamakua Volcanics of Mauna Kea. Below 340m to 1056m is a 675m-thick section of shield-building Mauna Kea tholeiites. At a given MgO content, the Mauna Kea flows are lower in SiO2 and total iron and higher in total alkali and TiO2 than the Mauna Loa lavas. The Mauna Kea parental magmas are more iron-rich and contain ~15 wt% MgO (~17 wt% MgO for Mauna Loa). The Mauna Loa lavas are controlled compositionally by olivine crystallization and accumulation and contain high-MgO tholeiites and picrites. Ratios such as Zr/Nb and Sr/Nb have remained roughly constant with the range for historical and young prehistoric lavas.

Label:

Geology

Collection:

Periodicals