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Structural geology and tectonic setting of the Cherry Creek Metamorphic Suite, southern Madison Range




Sumner, Wendolyn Rivers, author
Erslev, Eric A., advisor
Burns, Larry K., committee member
Thompson, Eric, committee member

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The Cherry Creek Metamorphic Suite, exposed in the core of the southern Madison Range in the northwestern Wyoming province, is a well-preserved, carbonate-quartzite-pelite shelf association of Archean age containing a coherent stratigraphic sequence. Relict sedimentary structures (161 measurements) reveal that stratigraphic up is to the southeast. Trace element geochemistry of the meta-turbidites indicates that the sediments were deposited in a back arc basin analogous to the Sea of Japan. Comparison of major element chemistry of the pelites with other suites in the northwest Wyoming Province suggest a similar provenance throughout the region. Repetition and truncation of the Cherry Creek stratigraphy occurs along a series of narrow, southeast dipping mylonite zones of Late Archean age. Petro-fabric analyses of C-S surfaces, asymmetrical mineral retorts, and rolled garnets indicate oblique thrusting to the northwest. Strain analysis of psammitic portions of meta-turbidites indicates largely flattening strains and bulk shortening of the Cherry Creek Metamorphic Suite, with associated plane strain localized in thrust zones. Prograde (middle-amphibolite facies) mineral growth lineation's parallel fold axes in zones of heterogeneous shear, suggesting synchronous prograde metamorphism and deformation. Down-plunge projection of fabric, strain and map relationships demonstrate tectonic thickening of the Cherry Creek Metamorphic Suite by thrust imbrication and duplex stacking. This thin-skin deformation is closely analogous to many post-Archean convergent belts, suggesting similar tectonic processes during the Archean.


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Geology, Structural
Geology, Stratigraphic -- Archaean
Geology -- Wyoming


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