Paul Sotiriou ^a,b,*, Ali Polat ^a, Tim Kusky ^c, Brian F. Windley ^d

a School of the Environment, University of Windsor, Windsor, ON N9B 3P4, Canada

b GeoZentrum Nordbayern, Friedrich-Alexander-Universität, Erlangen 91054, Bayern, Germany

c Center for Global Tectonics, State Key Laboratory for Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, Hubei Province, PR China

d School of Geography, Geology and the Environment, University of Leicester, Leicester LE1 7RH, UK

In a paper in 1970, Brian Windley first recognised that early terrestrial and lunar anorthosites both have

calcic plagioclase, and low TiO2 and high CaO and Al2O3 contents. Despite these similarities, the geochemistry

of early terrestrial and lunar anorthosites has not been rigorously compared and contrasted. To this

end, we compiled 425 analyses from 212 early terrestrial anorthosite occurrences and 306 analyses from

16 lunar anorthosite occurrences. This was supplemented by a compilation of plagioclase anorthite (An)

contents and pyroxene Mg# from early terrestrial and lunar anorthosites. Early terrestrial anorthosites

have lower whole-rock An contents but similar Mg# to lunar anorthosites. The CaO contents of lunar

anorthosites are higher than those of early terrestrial anorthosites for a given MgO and Al2O3 content,

early terrestrial anorthosites have higher SiO2 contents than lunar anorthosites at a given MgO content,

and lunar anorthosites have higher Eu/Eu* anomaly ratios yet broadly similar La/Yb and Nd/Sm ratios

than early terrestrial anorthosites. Some early terrestrial anorthosites have less fractionated chondritenormalised

rare earth element (REE) patterns and less prominent positive Eu anomalies than lunar

anorthosites. Lunar anorthosites have higher plagioclase An contents, yet a similar range of pyroxene

Mg# compared to their early terrestrial counterparts. Some early terrestrial anorthosites are more fractionated

than some lunar anorthosites. Our interpretations imply that most early terrestrial anorthosites

crystallised from basaltic parental magmas that were generated by high-degree partial melting of sub-arc

asthenosphere mantle wedge sources that were hydrated by slab-derived fluids, with the remainder

being associated with mid-ocean ridge and mantle plume settings. Some of the arc-related early terrestrial

anorthosites were influenced by crustal contamination. In addition, early terrestrial anorthosites

originated from partial melting of the mantle at various depths with variable garnet residua, whereas

lunar anorthosites formed without any significant garnet residua. Lower plagioclase CaO contents and

pyroxene Mg# in early terrestrial anorthosites can be explained by higher proportions of clinopyroxene

and olivine fractionation in terrestrial magma chambers than in the lunar magma ocean where orthopyroxene

and olivine fractionation occurred. Low TiO2 contents in both terrestrial and lunar anorthosites

reflect rutile and/or ilmenite fractionation.

2024 China University of Geosciences (Beijing) and Peking University. Published by Elsevier B.V. on

behalf of China University of Geosciences (Beijing). This is an open access article under the CC BY-NC-ND

license (http://creativecommons.org/licenses/by-nc-nd/4.0/).