High-resolution TEM study of jimthompsonite, chesterite, and chain-width disorder in Archean ultramafic rocks from Isua, West Greenland

摘要

Jimthompsonite and chesterite occur as intergrowths within anthophyllite up to a few millimeters across in talc-magnesite schist from the ~3800 Ma Isua Supracrustal Belt, West Greenland. Pyribole lamellae span the entire intergrowth width and have their own crystal faces. The schist is strongly foliated and pyribole intergrowths are aligned with this foliation indicating broad synchronicity among metamorphic deformation, recrystallization, and pyribole formation.