Journal article

Layered mantle lithosphere in the Lac de Gras area, Slave Craton: Composition, structure and origin

WL Griffin, BJ Doyle, CG Ryan, NJ Pearson, SY O'Reilly, R Davies, K Kivi, E Van Achterbergh, LM Natapov

JOURNAL OF PETROLOGY | OXFORD UNIV PRESS | Published : 1999

Abstract

Heavy-mineral concentrates (garnets, chromites) and xenoliths from 21 Cretaceous-Tertiary kimberlite intrusions have been used to map the lithospheric mantle beneath the Lac de Gras area in the central part of the Slave Province. Analyses of Nickel Temperature (T(Ni)) and Zinc Temperature (T(Zn)) have been used to place garnet and chromite xenocrysts, respectively, in depth context. Paleogeotherms derived from both xenoliths and concentrates lie near a 35 mW/m2 conductive model at T ≤ 900°C, and near a 38 mW/m2 model at higher T, implying a marked change in conductivity and/or a thermal transient. Plots of garnet composition vs T(Ni) also show a sharp discontinuity in mantle composition at 9..

View full abstract

University of Melbourne Researchers