Deformation characteristics of the Sheeprock and Canyon Range thrust sheets (Sevier orogenic belt) based on microstructural and strain studies

Conference · Thu Apr 01 00:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5128765

Sussman, A J; Mitra, G ^[1]

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1. Univ. of Rochester, NY (United States). Dept. of Geological Sciences

The condition of emplacement of internal thrust sheets in the Sevier fold-and-thrust belt can be characterized by detailed studies on deformation of quartzites within these sheets. The Sheeprock and Canyon Range thrust sheets in north-central Utah both carry Proterozoic Caddy Canyon and Mutual quartzites in their hanging walls. The Caddy Canyon is a medium to coarse-grained quartzite with subrounded grains and some grain-overgrowth. The Mutual is typically coarse-grained to pebbly, has subrounded to well rounded grains with overgrowths, and is characterized by clasts showing an older metamorphic (in some cases, mylonitic) fabric. In the Sheeprock sheet both quartzites show evidence for considerable crystal-plastic deformation, including deformation lamellae, undulose extinction, and development of subgrains; the Caddy Canyon also shows considerable pressure solution. Late stage cataclasis, characterized by the development of cemented cataclasites, is also evident. In the Canyon Range, both quartzites show less plastic deformation, although the Caddy Canyon shows large amounts of pressure solution. The late stage cataclasites are coherent but not cemented, and there is locally strong plastic deformation adjacent to the cataclasite zones. The microstructures suggest an overall shallower level of deformation for the Canyon Range sheet. Strains in the quartzites are quantified using the Fry technique, and the strains are partitioned into plastic and diffusional components using deformed rutile needles within quartz grains and pressure-solved grain shapes.

• OSTI ID: 5128765
• Report Number(s): CONF-9305259-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GEOLOGIC FORMATIONS
DEFORMATION
QUARTZITES
PETROLOGY
UTAH
GEOLOGIC FAULTS
GEOLOGIC STRATA
MICROSTRUCTURE
PLASTICITY
STRAINS
STRESS ANALYSIS
DEVELOPED COUNTRIES
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGY
MECHANICAL PROPERTIES
METAMORPHIC ROCKS
NORTH AMERICA
ROCKS
USA
580000* - Geosciences