Recognizable primary volcanic and sedimentary features in a low‐strain domain of the highly deformed, oldest known (≈ 3.7–3.8 Gyr) Greenstone Belt, Isua, West Greenland

Abstract

A low‐strain domain has been identified in the metamorphosed, mostly highly deformed volcanic and sedimentary rocks of the early Archaean Isua supracrustal belt. This domain contains well‐preserved volcanic and sedimentary features, including basaltic pillow lavas, pillow breccia, heterogeneous volcanic breccia, amygdules in metabasalt, and polymict conglomerate dominated by recrystallized chert and volcanic clasts. The low‐strain domain is bounded by highly deformed rocks mostly derived from basalt, chert, and banded iron formation. These discoveries demonstrate that some primary features have escaped the pervasive metasomatism dominant in other parts of the belt and, furthermore, strengthen the characterization of the Isua supracrustals as a typical greenstone belt.