Granulite sulphides as tracers of lower crustal origin and evolution

An example from the Slave craton, Canada

Sonja Aulbach*, Cristen Krauss, Robert A. Creaser, Thomas Stachel, Larry M. Heaman, Sergei Matveev, Thomas Chacko

*Corresponding author for this work

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We carried out a detailed study of sulphide minerals, a ubiquitous mineral group in lower crustal mafic to peraluminous granulite xenoliths from the Diavik kimberlites, to assess their use in constraining the origin and tectonothermal evolution of the deep crust, and to obtain additional data on the composition of lower crust beneath ancient continents. Sulphides are overwhelmingly pyrrhotite with minor Ni (0.7-3.9 at.%), Co (0.1-0.7 at.%), and Cu contents (0.4-3.9 at.%). Sulphide modes in mafic granulites range from 0.14 to 0.55 vol%, translating into bulk rock S contents from ∼600 to 2000 ppm, similar to S contents in other mafic igneous rocks and indicating preservation of primary igneous S contents. In mafic granulites, Re and Os abundances in sulphides range from 42.5 to 726 ppb and 3.2 to 180 ppb, respectively, whereas those in peraluminous granulites are distinctly lower (36.1-282 ppb and 1.8-7.2 ppb, respectively), suggestive of Re and Os loss to fractionating sulphides in the more evolved precursors of these rocks. The significant within-sample variability of 187Os/188Os and correlation with 187Re/188Os indicates the preservation of primary Re-Os isotope systematics and time-integrated decay of the measured 187Re. Within the large uncertainties inherent in the nature of the samples and technique, sulphides in some granulites may record major tectonothermal events in the central Slave craton spanning several billion years of evolution. Multiple generations of sulphide can occur in a single sample. These data attest to the heterogeneous composition and complex history of the Slave craton lower crust.

Original languageEnglish
Pages (from-to)5368-5381
Number of pages14
JournalGeochimica et Cosmochimica Acta
Volume74
Issue number18
DOIs
Publication statusPublished - Sep 2010
Externally publishedYes

Fingerprint Dive into the research topics of 'Granulite sulphides as tracers of lower crustal origin and evolution: An example from the Slave craton, Canada'. Together they form a unique fingerprint.

  • Cite this