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- Title
Mafic to ultramafic xenoliths from Mauna Kea, Hawaii: clues to magma evolution from trace element compositions of clinopyroxene.
- Authors
Sjoblom, Megan Pickard; Dorais, Michael J.; Christiansen, Eric H.; Fodor, Ronald V.
- Abstract
Mafic and ultramafic xenoliths were erupted with hawaiite lavas from a post-shield, Laupahoehoe cinder cone on Mauna Kea volcano, Hawaii. Major element compositions of clinopyroxene, olivine, and plagioclase in these xenoliths do not clearly differentiate between parental Hawaiian tholeiitic, transitional, or alkalic magmas. To clarify the parental magma compositions, incompatible trace element concentrations in clinopyroxene were analyzed by laser ablation inductively coupled plasma mass spectrometry. The compositions of equilibrium liquids were calculated using published clinopyroxene/basalt partition coefficients. The REE patterns and concentrations of Sr, Ba, Ti, and Zr in most calculated liquids are similar to transitional and alkalic lavas of post-shield Hamakua Volcanics and unlike the younger host lava, the more alkalic Laupahoehoe Volcanics. In contrast, liquids in equilibrium with clinopyroxene in a wehrlite and an olivine gabbro have trace element concentrations similar to tholeiitic shield basalts. Thus, these xenoliths represent cumulates crystallized at depth from the shield stage tholeiitic and post-shield Hamakua magmas and were then entrained in the younger alkalic Laupahoehoe lavas. The composition of the xenoliths and the calculated liquids show that the Hamakua Volcanics and Laupahoehoe Volcanics are not related to one another by deep fractionation, but instead are derived from compositionally distinct sources and different degrees of melting.
- Subjects
MAUNA Kea (Hawaii); HAWAII; LASER ablation inductively coupled plasma mass spectrometry; INCLUSIONS in igneous rocks; TRACE elements; THOLEIITE; MAGMAS
- Publication
Contributions to Mineralogy & Petrology, 2023, Vol 178, Issue 3, p1
- ISSN
0010-7999
- Publication type
Article
- DOI
10.1007/s00410-023-02001-3