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The end of continental growth by TTG magmatism

Laurie, L.; Stevens, G.; van Hunen, J.


L. Laurie

G. Stevens


High-Al2O3 tonalite, trondhjemite and granodiorite (TTG) magmas characterise felsic Archaean crust, yet are uncommon in the post-Archaean rock record. Consequently, understanding the petrogenesis of these rocks provides valuable insights into early Earth processes. Fluid-absent slab melting represents the dominant hypothesis for the origin of these rocks; however, the absence of voluminous magmas of intermediate composition formed concurrently with these TTGs is incompatible with expectations of slab water loss prior to slab melting. This study demonstrates that for reasonable Archaean mantle temperatures, slab-derived water is captured by an anatectic zone near the slab surface, which melts via reactions that consume quartz, clinopyroxene and water to produce high-Al2O3 Archaean trondhjemite. Late in the Archaean, the mantle cooled sufficiently to prevent wet melting of the slab, allowing slab water to migrate into the wedge and produce intermediate composition magmatism, which has since been associated with subduction zones.


Laurie, L., Stevens, G., & van Hunen, J. (2012). The end of continental growth by TTG magmatism. Terra Nova, 25(2), 130-136.

Journal Article Type Article
Acceptance Date Oct 16, 2012
Online Publication Date Nov 14, 2012
Publication Date Nov 14, 2012
Deposit Date May 9, 2013
Journal Terra Nova
Print ISSN 0954-4879
Electronic ISSN 1365-3121
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 25
Issue 2
Pages 130-136