Age and evolution of a late Archean to Paleoproterozoic upper to lower crustal section in the Wutaishan/Hengshan/Fuping terrain of northern China

We interpret the Hengshan and Fuping granitoid gneisses as the lower, plutonic, part of a late Archean to early Paleoproterozoic Japan-type magmatic arc, with the upper, volcanic part represented by the Wutai complex. Components of this arc may have evolved at a continental margin as indicated by the 2.7 Ga zircons. Virtually all magmatic events are recorded in all three complexes. However, the 1.85 Ga metamorphic event is only recorded in the higher-grade portions of the Wutai, since low-grade and presumably high crustal level precluded metamorphic zircon growth. Shear zones in the Hengshan are interpreted as major lower crustal discontinuities post-dating the peak of high-pressure granulite metamorphism. We suggest that they formed during orogenic collapse and uplift of the Hengshan complex in the late Paleoproterozoic (>1800 Ma).