Strain-collapsed metamorphic isograds in a sillimanite gneiss dome, Seward Peninsula, Alaska

Journal Article · Mon Jun 01 04:00:00 EDT 1992 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1992)020<0487:SCMIIA>2.3.CO;2· OSTI ID:7004332

Miller, E L; Calvert, A T; Little, T A ^[1]

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1. Stanford Univ., CA (United States)

Unusually closely spaced Barrovian series isograds have been described along the flanks of the Kigluaik Mountains, Seward Peninsula, Alaska, where they separate a high-grade gneiss complex intruded by granites of Cretaceous age from surrounding, regionally developed, blueschist to greenschist facies rocks. Structural mapping of the transition zone between the two metamorphic types indicates that their juxtaposition was aided by significant syn- to late-metamorphic solid-state flow that served to attenuate the overlying rock column and thus collapse the field metamorphic gradient. On the basis of field relations, structural data, petrography, and geochronologic data, strain appears to have accompanied the rapid (adiabatic) rise of high-temperature rocks from several tens of kilometers to less than 10 km depth during the Cretaceous, in an event younger than the unrelated to high-P metamorphism. Granite-cored gneiss domes on the Seward Peninsula may have formed during extension of previously thickened continental crust, resulting in the {approximately}35-km-thick crust and near-sea-level elevations of the region today.

• OSTI ID: 7004332
• Journal Information: Geology; (United States), Journal Name: Geology; (United States) Vol. 20:6; ISSN GLGYB; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ALASKA
CRETACEOUS PERIOD
DEVELOPED COUNTRIES
DUCTILITY
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GNEISSES
MAPPING
MECHANICAL PROPERTIES
MECHANICS
MESOZOIC ERA
METAMORPHIC ROCKS
METAMORPHISM
NORTH AMERICA
PETROGENESIS
PETROGRAPHY
ROCK MECHANICS
ROCKS
TECTONICS
TENSILE PROPERTIES
USA