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<p>The Beartooth Mountains of Montana and Wyoming, USA, record more than 4.0&#xa0;billion years of Earth history. This area has inspired a century of geological research and contributed to the evolution of geological thought. This spectacular Alpine landscape supports diverse geoeducational and geotourism opportunities. Geologic features of the Beartooth Mountains include: (a) physiographic occurrence as a basement-cored, Laramide-style block uplift; (b) in the eastern Beartooth Mountains, preservation of Paleoarchean high-grade metamorphic gneisses and metasupracrustal rocks with peak metamorphism recorded at 6–8 kbar and up to 800&#xa0;°C and crystallization ages of 3.5–3.0 Ga, with detrital zircons as old as 4.0 Ga; (c) in the main Beartooth Block, voluminous Mesoarchean calc-alkaline magmatic rocks dated at 2.82–2.79 Ga that formed in a continental magmatic arc environment; (d) in the South Snowy Block, tectonic accretion of a turbiditic metasedimentary sequence that was deposited and emplaced 2.9–2.8 Ga that preserves primary sedimentary structures, and with peak metamorphism of 3–4 kbar and 580&#xa0;°C, and in the North Snowy Block, emplacement of an Alpine-style nappe complex prior to 2.55 Ga; (e) on the northern margin of the range in the Stillwater block, crystallization of the 2.71 Ga layered mafic-ultramafic Stillwater Complex which is host to Pt/Pd and Cr ore deposits and associated contact metamorphic aureole; (f) emplacement of Late Archean and Proterozoic mafic dikes at 2.5, 1.3 and 0.75 Ga; (g) near Beartooth Butte, deposition of lower Paleozoic sedimentary rocks on the Great Unconformity with 2.8 Ga crystalline rocks overlain by 560&#xa0;Ma Cambrian sedimentary rocks and preservation of some of the world’s oldest Devonian fish and terrestrial plant fossils; i) Eocene Absaroka volcanics, which hosts petrified forests, the Heart Mountain Detachment, and Au-Cu deposits; j) Pleistocene glacial deposits and periglacial landscapes; k) active basin-and-range style faulting; and l) active landsliding and floods. The natural heritage of the Beartooth Mountains has had a great influence on the people who live in this area and how they live in this landscape including habitation history of indigenous people and émigrés, development and exploitation of natural resources (mining, energy, water), impacts of geohazards (seismicity, floods, mass wasting), opportunities for geoeducation at all levels, as a destination for geotourism, and in consideration of contemporary policy questions related to conservation vs. preservation of public lands and climate change. The Archean rocks of the eastern Beartooth Mountains and the Stillwater Complex have both been recognized as “First Hundred Geological Heritage Sites” by the International Union of Geological Sciences. The Beartooth Mountains constitute a geoheritage region of international significance with many sites of interest for expert and novice geoscientists alike.</p>

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The Geoheritage of the Beartooth Mountains, Montana and Wyoming, USA: Traversing Four Billion Years of Earth History

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  • 发表日期：

    2025年11月17日

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  • David W. Mogk,
  • Paul A. Mueller,
  • Darrell J. Henry

摘要

The Beartooth Mountains of Montana and Wyoming, USA, record more than 4.0 billion years of Earth history. This area has inspired a century of geological research and contributed to the evolution of geological thought. This spectacular Alpine landscape supports diverse geoeducational and geotourism opportunities. Geologic features of the Beartooth Mountains include: (a) physiographic occurrence as a basement-cored, Laramide-style block uplift; (b) in the eastern Beartooth Mountains, preservation of Paleoarchean high-grade metamorphic gneisses and metasupracrustal rocks with peak metamorphism recorded at 6–8 kbar and up to 800 °C and crystallization ages of 3.5–3.0 Ga, with detrital zircons as old as 4.0 Ga; (c) in the main Beartooth Block, voluminous Mesoarchean calc-alkaline magmatic rocks dated at 2.82–2.79 Ga that formed in a continental magmatic arc environment; (d) in the South Snowy Block, tectonic accretion of a turbiditic metasedimentary sequence that was deposited and emplaced 2.9–2.8 Ga that preserves primary sedimentary structures, and with peak metamorphism of 3–4 kbar and 580 °C, and in the North Snowy Block, emplacement of an Alpine-style nappe complex prior to 2.55 Ga; (e) on the northern margin of the range in the Stillwater block, crystallization of the 2.71 Ga layered mafic-ultramafic Stillwater Complex which is host to Pt/Pd and Cr ore deposits and associated contact metamorphic aureole; (f) emplacement of Late Archean and Proterozoic mafic dikes at 2.5, 1.3 and 0.75 Ga; (g) near Beartooth Butte, deposition of lower Paleozoic sedimentary rocks on the Great Unconformity with 2.8 Ga crystalline rocks overlain by 560 Ma Cambrian sedimentary rocks and preservation of some of the world’s oldest Devonian fish and terrestrial plant fossils; i) Eocene Absaroka volcanics, which hosts petrified forests, the Heart Mountain Detachment, and Au-Cu deposits; j) Pleistocene glacial deposits and periglacial landscapes; k) active basin-and-range style faulting; and l) active landsliding and floods. The natural heritage of the Beartooth Mountains has had a great influence on the people who live in this area and how they live in this landscape including habitation history of indigenous people and émigrés, development and exploitation of natural resources (mining, energy, water), impacts of geohazards (seismicity, floods, mass wasting), opportunities for geoeducation at all levels, as a destination for geotourism, and in consideration of contemporary policy questions related to conservation vs. preservation of public lands and climate change. The Archean rocks of the eastern Beartooth Mountains and the Stillwater Complex have both been recognized as “First Hundred Geological Heritage Sites” by the International Union of Geological Sciences. The Beartooth Mountains constitute a geoheritage region of international significance with many sites of interest for expert and novice geoscientists alike.