The geochemistry of Archean anorthosite-bearing layered intrusions has major implications for the thermal and

chemical state of the Archean crust/mantle system, as originally posited by Bowen (1917) as “the anorthosite

problem” and expanded on by Ashwal (1993). Debates have centred on the nature of the parental magmas,

emplacement mechanisms and geodynamic settings of Archean anorthosites, many of which have megacrystic

textures. In this review, we have compiled whole-rock major and trace element and Nd isotope geochemical data

from Archean anorthosite-bearing layered intrusions worldwide to address the outstanding questions outlined

above regarding the petrogenesis of anorthosites. Archean anorthosite-bearing layered intrusions were not

significantly affected by hydrothermal alteration and were derived from depleted mantle sources and most (85%)

were emplaced in oceanic settings. Some intrusions were intruded in continental settings or ocean-continent

transition zones, reflecting the emergence of continents in the Paleoarchean into the Neoarchean. Based on

their petrography and major and trace element geochemistry, Archean anorthosite-bearing layered intrusions

mostly crystallised from hydrous Ca- and Al-rich tholeiitic magmas that fractionated from more primitive

tholeiitic parental magmas. Archean layered intrusions formed by shallow- and deep-level fractional crystallisation

of tholeiitic magmas and predominantly formed in back-arc suprasubduction zone and volcanic arc

settings. Archean anorthosite-bearing layered intrusions started forming at ca. 3850 Ma, most of them representing

relicts of dismembered Archean subduction-related ophiolites. Modern-style plate tectonic processes

have operated at least since the earliest Archean and were the predominant contributor to Archean crustal

growth.