Early Proterozoic Ultrahigh Pressure Metamorphism: Evidence from Microdiamonds

Microdiamonds from the Akluilâk minette dykes (Nunavut, Canada) are similar to diamonds formed in subducted metamorphic rocks. High concentrations of unaggregated nitrogen and positive δ 15 N suggest that the microdiamonds formed within rocks subducted to ultrahigh pressures before being sampled by...

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Bibliographic Details
Published in:Science
Main Authors: Cartigny, Pierre, Chinn, Ingrid, Viljoen, K. S. (Fanus), Robinson, Derek
Format: Article in Journal/Newspaper
Language:English
Published: American Association for the Advancement of Science (AAAS) 2004
Subjects:
Nunavut
Online Access:http://dx.doi.org/10.1126/science.1094668
https://www.science.org/doi/pdf/10.1126/science.1094668
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Summary:Microdiamonds from the Akluilâk minette dykes (Nunavut, Canada) are similar to diamonds formed in subducted metamorphic rocks. High concentrations of unaggregated nitrogen and positive δ 15 N suggest that the microdiamonds formed within rocks subducted to ultrahigh pressures before being sampled by the minette magma 1.8 billion years ago. This ultrahigh pressure metamorphism in North America, probably related to the Trans-Hudson orogen (about 2 billion years ago), extends the occurrence of ultrahigh pressure metamorphism from 0.6 billion years to before 1.8 billion years ago and suggests that Phanerozoic-type subductions were active by the Early Proterozoic.

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