Fractional crystallisation of eclogite during the birth of a Hawaiian Volcano

Laura A Miller; Hugh St C O'Neill; Andrew J Berry; Charles Le Losq

doi:10.1038/s41467-022-30108-x

Fractional crystallisation of eclogite during the birth of a Hawaiian Volcano

Nat Commun. 2022 May 26;13(1):2946. doi: 10.1038/s41467-022-30108-x.

Authors

Laura A Miller^{1

2}, Hugh St C O'Neill³, Andrew J Berry⁴, Charles Le Losq⁵

Affiliations

¹ School of Earth, Atmosphere and Environment, Monash University, Clayton, VIC, 3800, Australia. laura.miller@monash.edu.
² Research School of Earth Sciences, Australian National University, Canberra, ACT, 2601, Australia. laura.miller@monash.edu.
³ School of Earth, Atmosphere and Environment, Monash University, Clayton, VIC, 3800, Australia.
⁴ Research School of Earth Sciences, Australian National University, Canberra, ACT, 2601, Australia.
⁵ Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, F-75005, Paris, France.

Abstract

The initial melts erupted by a Hawaiian volcano have a range of alkalic compositions but are rarely observed as they are covered by enormous volumes of shield stage tholeiites. A remarkable record of the early evolution of Hawaiian volcanoes, however, is preserved by a volcanic sandstone dredged from the submarine flank of Kilauea, which contains a suite of petrogenetically related pre-shield basanite to nephelinite glasses. Here we show that the systematic variation in the rare earth element (REE) patterns of these samples requires the fractional crystallisation of garnet. A fractionating assemblage of Ca-rich garnet (32%), omphacitic clinopyroxene (63%), and minor phlogopite can explain the variation in the major and trace element contents of the suite. The results suggest fractional crystallisation of eclogite from a primitive Hawaiian melt near the base of the lithosphere (>90 km) and that a deep magma chamber is the first stage in the development of a Hawaiian volcano.