Lapis lazuli from Baffin island - a precambrian meta-evaporite

D. D. Hogarth*, W. L. Griffin

*Corresponding author for this work

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

On Baffin Island, the major minerals in lapis lazuli are calcite, lazurite, diopside, nepheline and phlogopite in the Main Occurrence and calcite, lazurite, diopside, plagioclase and scapolite in the North Occurrence. The abundances of Na, K, S, Cl, Br, F and Fe, the well-developed layering parallel to the regional foliation, and the scarcity of intrusive rocks, support the hypothesis that the deposit evolved from an evaporite parent during regional metamorphism. After sedimentation, considerable reduction of sulfur was effected by CO, perhaps aided by H2, Cl- and anaerobic bacteria. Chemographic analysis suggests that the observed phase assemblages represent local equilibrium within small volumes, where SiO2-Al2O3-MgO-Na2O-K2 O behaved as inert components at the peak of metamorphism. The lack of systematic zoning of phase assemblages, and the uniformity of mineral compositions within the deposit, also argue against a metasomatic origin. Most phases equilibrated at or near the peak of metamorphism (granulite facies).

Original languageEnglish
Pages (from-to)37-60
Number of pages24
JournalLithos
Volume11
Issue number1
DOIs
Publication statusPublished - 15 Jan 1978
Externally publishedYes

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