Antler orogeny it have been tried—east dipping subduction, west-dipping subduction, and strike-slip motion. None of them is without serious problems and the nature and driving force of the orogeny remain uncertain. This much is known concerning the Antler orogeny: Based on stratigraphic relations near Antler Peak, of the Battle Mountains, Roberts introduced the term Antler orogeny in an abstract as follows: "The earliest orogeny, here named the Antler orogeny ... took place during Mississippian (?) and early Pennsylvanian time." That abstract was followed in 1951 by his geologic map of the Antler Peak quadrangle in the text of which he described the
Grenville orogeny of Laurentia, and likely collided with a different continent than that involved in the eastern collision. The Zapotecan Orogeny of Mexico is coeval with the later stages of the Grenville orogeny, and they are generally considered to be one and the same. Mesoproterozoic igneous protoliths (metamorphosed to granulite facies during the orogeny) fall into two age groups in Mexico; c. 1235–1115 Ma and c. 1035–1010 Ma. Rocks of the former group bear geochemical signatures implying island arc and back-arc basin provenance. The latter group represents AMCG magmatism. These AMCG rocks are somewhat anomalous throughout the Grenville orogen, there is no