eCite Digital Repository

Metapyroxenite in the mantle transition zone revealed from majorite inclusions in diamonds


Kiseeva, ES and Yaxley, GM and Stepanov, AS and Tkalcic, H and Litasov, KD and Kamenetsky, VS, Metapyroxenite in the mantle transition zone revealed from majorite inclusions in diamonds, Geology, 41, (8) pp. 883-886. ISSN 0091-7613 (2013) [Refereed Article]

Copyright Statement

Copyright 2013 Geological Society of America

DOI: doi:10.1130/G34311.1


The transition zone of the Earth's mantle (the depth interval between two major seismic discontinuities at 410 km and 660 km) is critical to understanding our planet's evolution. Some diamonds are thought to have originated in the transition zone and the inclusions found in them are the only samples of material directly extracted from this depth range. By comparing natural majorite garnet inclusions in diamonds with the compositions of experimentally crystallized majorite garnets, we determine two major compositional trends, the pure metabasitic (or eclogitic) trend and the combined metaperidotitic and metapyroxenitic trend, that are strongly correlated with their preferred substitution mechanisms during majorite formation. Based on these trends, we demonstrate that the majority of the reported majorite inclusions in natural diamonds formed neither in a pure metabasite nor in a metaperidotite lithology, but in fact crystallized from a wide range of compositions intermediate between conventional basaltic and peridotitic, referred to here as metapyroxenitic. Given the dominance of metapyroxenite-type majorite diamond inclusions and their inferred syngenetic origin, we argue that a significant fraction of metapyroxenite rock is present within Earth's transition zone and is important in the diamond-forming process. This is in agreement with recent self-consistent seismological and/or mineral physics studies that support models of a lithologically heterogeneous transition zone. From trace element and carbon isotope features, we infer a crustal origin for these rocks.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Geology
Research Field:Igneous and metamorphic petrology
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Stepanov, AS (Mr Sasha Stepanov)
UTAS Author:Kamenetsky, VS (Professor Vadim Kamenetsky)
ID Code:86609
Year Published:2013
Web of Science® Times Cited:33
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2013-10-02
Last Modified:2017-11-02

Repository Staff Only: item control page