The characterization of mafic phyllosilicates in low-grade metabasalts from eastern North Greenland

Utilizing a combination of petrographic, XRD, and EPMA data, a progressive sequence of mafic phyllosilicates from random mixed- layer chlorite/smectite (approx 25% chlorite) through different types of regular mixed-layer chlorite/smectite (approx 60, 65, 80, and 85% chlorite) to discrete chlorite has been identified in basalts affected by low-grade regional metamorphism from the late Proterozoic Zig-Zag Dal basalt formation of E North Greenland. The results presented emphasize some of the difficulties of identifying mafic phyllosilicates on the basis of limited optical and microprobe data.