Abstract
The northern complex is an Archean greenstone-granitoid terrane located in Upper Michigan at the southern margin of the Superior Province, interpreted as a product of N-directed subduction followed by continental collision. Amphibole-bearing granitoids in the northern complex have comparable field relationships, textures and compositions to Paleozoic appinites emplaced during the Caledonian orogeny in the British Isles. We suggest that the rocks in the northern complex represent an Archean appinite suite. The northern complex appinites vary from olivine-normative hornblende cumulates to quartz-normative hornblende diorites. Hornblendite is characterized by high Mg-numbers and elevated Cr, Ni, and Sc content whereas diorite is more fractionated with lower Mg-numbers and is comparatively enriched in the large-ion-lithophile elements (e.g., K, Rb, Sr, and Ba). Rare-earth elements show negligible Eu anomalies and a progressive increase of $[Ce/Yb]_{N}$ ratios from hornblendites to diorites. Geochemical charac...
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