Metamorphic core complex

Formation of a metamorphic core complex

Metamorphic core complexes are exposed areas of deep crust brought to the surface by crustal extension (stretching).[1] They form, and are exhumed, through relatively fast[citation needed] transport of middle and lower continental crust to the Earth's surface[2] in the form of uplifting welts of hot rock and magma.[1] The resulting doming causes the overlying rock to gravitationally collapse, sliding down and usually away from the uplift along low-angle detachment faults.[1] Brittle, faulted cover rock above the detachment surface lies in direct contact with the ductile middle-lower crust below.[3]

High-grade metamorphic rocks (eclogite-, granulite- to amphibolite- facies) are exposed below the detachment faults (and mylonitic shear zones).[citation needed] Amphibolite- to greenschist-facies, syndeformational metamorphism, and ductile-brittle to brittle deformation are shown on the upper-side (hanging-wall), with tilted geometries.[citation needed]

They range from several miles to over 50 miles across, and usually exhibit several miles of vertical uplift.[1] They are common in areas of localized crustal extension in otherwise thickened fold-thrust belts.[1][clarification needed] The origin of the low angles of the detachment faults were a subject of debate as of 2022.[3]

  1. ^ a b c d e "What is a Metamorphic Core Complex". Utah Geological Survey.
  2. ^ Lister, G.S.; Davis, G.A. (1989). "The origin of metamorphic core complexes and detachment faults formed during Tertiary continental extension in the northern Colorado River region, U.S.A." (PDF). J. Struct. Geol. 11 (1–2): 65–94. Bibcode:1989JSG....11...65L. doi:10.1016/0191-8141(89)90036-9.
  3. ^ a b Bahadori, Alireza; Holt, William E.; Austermann, Jacqueline; Campbell, Lajhon; Rasbury, E. Troy; Davis, Daniel M.; Calvelage, Christopher M.; Flesch, Lucy M. (2022-09-26). "The role of gravitational body forces in the development of metamorphic core complexes". Nature Communications. 13 (1): 5646. Bibcode:2022NatCo..13.5646B. doi:10.1038/s41467-022-33361-2. ISSN 2041-1723. PMC 9513114. PMID 36163354.