EXTENDING THE DESCRIPTION AND CORRELATION OF MAP UNITS WITH A FEATURE-LEVEL CATALOG OF CRETACEOUS-PALEOGENE MAGMATISM IN SOUTHWESTERN MONTANA

The Boulder batholith and surrounding landscape (southwestern Montana, USA) contain numerous mineral deposits intimately associated with Cordilleran foreland magmatism, driving major new airborne geophysical and geologic investigations funded by Earth MRI and other USGS programs. A comprehensive catalog of magmatic systems, or other sets of features, can facilitate: (a) exhaustive compilation of legacy data and existing knowledge; (b) identification of data and knowledge gaps to target with analytical and field work; and (c) clear communication between researchers with diverse specialties. Such catalogs can also serve as a stage for synthesis of map data, field relationships, structural observations, geochronology, geochemistry, and geophysics to better characterize mineral systems. However, information about specific geologic features such as individual faults and intrusions or fault networks and intrusive suites is recorded in a variety of data sets and publications. Geologic maps show mappable features and provide descriptions and correlations of map units, but these are generally abstracted and more thorough descriptions of specific features (e.g. individual intrusions) restricted to reports or papers. Given these and other issues when compiling geologic map data (e.g. variable scales and lithostratigraphic divisions), deriving comprehensive and rigorous descriptions of geologic features from existing work is not trivial.

We have designed a preliminary feature-level catalog of Cretaceous-Paleogene magmatism in southwestern Montana to better understand the relationships between mineral and magmatic systems of this region. This catalog summarizes names, descriptions, locations, and known ages for individual intrusions, co-genetic intrusive suites, and volcanic successions as well as mineral systems. Like map unit descriptions and correlation charts, the catalog encodes the hierarchical relationships among individual intrusive phases, intrusions, intrusive suites, and broader magmatic centers. Each record in the catalog will ultimately be linked with corresponding spatial vector data to facilitate data fusion of new and existing work. This feature-level catalog also functions as an initial design for a database view, which could be derived by linking map, lithostratigraphic, geochronology, and analytical databases.