The Flat Tops Volcanic Field: 1. Lower Miocene open‐system, multisource magmatism at Flander, Trappers Lake

The lower Miocene lavas (23–20 Ma) of the Flat Tops volcanic field, NW Colorado, are one of the earliest and most voluminous phases of magmatic activity associated with the development of the Rio Grande rift. Flow‐by‐flow collections of the lavas at Flander, Trappers Lake, provide evidence for complex open‐system magma chamber processes. Geochemically, the lavas range from basalts to shoshonites and have concentrations of major and compatible …