Gravity and aeromagnetic maps of the Maroon Bells-Snowmass Wilderness and additions, Pitkin and Gunnison counties, Colorado

Aeromagnetic and complete Bouguer gravity anomaly maps have been prepared for the Maroon Bells-Snowmass Wilderness and additions, near Aspen, Colorado.  An extreme gravity low, which may be indicative of mineralization, occurs over the White Rock pluton in the southeastern part of the study area.  Modeling of the gravity and magnetic anomalies shows that the Sopris, Snowmass, and White Rock plutons are probably all stocks connected to a single batholith at depth.  Both Sopris and Snowmass stocks seem to be shaped like spikes bristling out of this common batholith; the Snowmass spike is vertical, the Sopris spike is inclined.  The Snowmass spike has a westward-extending flange, possibly related to the Elk Range thrust zone.  The White Rock stock is a massive conical lump on top of the underlying batholith.  Its complicated aeromagnetic signature seems partly due at least two magnetically distinct regions, which may represent altered zones or separate intrusions within the stock.  These regions occur under the Conundrum Creek and East Maroon Creek valleys and may represent favorable locations for mineralization.