Duluth Complex

Shaded-relief image showing the Duluth Complex arcing from Duluth to Pigeon Point, interrupting and splitting the Mesabi and Gunflint Ranges

The Duluth Complex, the related Beaver Bay Complex,[1] and the associated North Shore Volcanic Group are rock formations which comprise much of the basement bedrock of the northeastern part of the U.S. state of Minnesota in central North America.[2][3] The Duluth and Beaver Bay complexes are intrusive rocks formed about 1.1 billion years ago during the Midcontinent Rift; these adjoin and are interspersed with the extrusive rocks of the North Shore Volcanic Group produced during that same geologic event. These formations are part of the Superior Upland physiographic region of the United States, which is associated with the Laurentian Upland of the Canadian Shield,[4] the core of the North American Craton.

  1. ^ Boerboom, Terry; Miller, Jim; and Green, John, "Geologic Highlights of New Mapping in the Southwestern Sequence of the North Shore Volcanic Group and in the Beaver Bay Complex" in Green, Volcanic and Sedimentary Rocks (2004), p. 47.
  2. ^ Jirsa & Southwick, Mineral Potential (2000)
  3. ^ Jirsa, Boerboom et al., Geologic Map of Minnesota: Bedrock Geology map, accessed via the Minnesota Geology Topics webpage and selecting the "+Bedrock Geology" tab, and there selecting "Geologic Map of Minnesota's Bedrock Geology PDF".
  4. ^ Tapestry of Time and Terrain Archived May 15, 2006, at the Wayback Machine (2003).