Geophysics of Precambrian Terranes, Upper Midwest and Rocky Mountains

Science Center Objects

The project objective is to provide follow-up geophysical ground data acquisition and interpretation for areas involving Precambrian geologic settings in the Upper Midwest and Rocky Mountains. The project is designed fill gaps and to complement the high-quality aeromagnetic acquired during the USGS Earth Mapping Resources Initiative (Earth MRI).

Science Issue and Relevance

Precambrian rocks underlying the Upper Midwest and the Rocky Mountain region form the tectonic core of North America, and Archean and Proterozoic tectonic and magmatic events are fundamental to understanding the continent's evolution. These rocks also host numerous known and suspected mineral systems relevant to critical minerals, including some of the highest priority areas identified during the Earth Mapping Resources Initiative (Earth MRI) prioritization process. Delineation and prioritization of focus areas considers an area's potential for undiscovered critical mineral deposits and identifies gaps in high-quality geophysical data and detailed geologic mapping. The resulting high-priority focus areas thus provide ideal opportunities to advance tectonomagmatic and metallogenic models and to better assess regional critical mineral potential.

Methods to Address Issue

This project plans to interpret data from four Earth MRI-sponsored airborne magnetic and radiometric surveys flown over high-priority areas, and to conduct focused geological studies to inform geophysical interpretations. Project objectives are: 

  • Develop new geologic framework and metallogenic interpretations to help inform future assessments 
  • Directly and collaboratively support Earth MRI-sponsored geologic mapping by State Geological Surveys 
  • Develop new interpretations to test postulated linkages between Superior and Wyoming cratons, and evaluate the implications for mineral systems models 

Task on this project are: 

Archean tectonomagmatic framework of the Mentor Complex region, northwest Minnesota: the area is a wide “transect” across the boundaries between three subprovinces of the Superior Province. Mafic/ultramafic intrusive complex is considered to have significant potential for numerous critical minerals. 

Paleoproterozoic tectonomagmatic framework of the Upper Peninsula, Michigan: the region’s mineral deposits, especially copper and iron, have been strategically important as far back as the Civil War. More recently, nickel, copper, platinum-group-elements (PGE), and cobalt have been the focus of exploration and mining. 

Lake Owen Complex and Cheyenne Belt, Wyoming: layered mafic intrusions along the southern margin of the Wyoming Province (Cheyenne Belt), especially the Lake Owen complex, have known mineralization of PGE and other critical / base metals of interest. 

Wet Mountains, Colorado, Precambrian and Cambrian terranes: focus on characterizing unique Cambrian intrusions that intrude Precambrian terranes and host critical minerals.


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