Intra-arc extension and magmatic evolution in the central Aleutian arc, Alaska
- Univ. of Wyoming, Laramie (USA)
New geologic, petrologic, and Sr isotope data from Seguam Island, Alaska, reveal substantial variation in the composition of magmas of the central Aleutian arc. The data indicate that variable magmatic processes occur along the strike of the arc. Seguam is situated on extended arc crust and has erupted voluminous basalt and dacite. In contrast to basalt from adjacent volcanic centers atop unextended crust, which evolved by polybaric open-system crystallization, Seguam lavas crystallized at shallow levels under closed-system conditions. Seguam basalt therefore better reflects the character of its source materials than basalt erupted through unextended arc crust. The authors conclude that along-arc differences in the nature of crystallization were facilitated by changes in the thermal and density structure of the subarc lithosphere caused by intra-arc extension.
- OSTI ID:
- 5796864
- Journal Information:
- Geology; (USA), Journal Name: Geology; (USA) Vol. 18:11; ISSN GLGYB; ISSN 0091-7613
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
ALASKA
ALEUTIAN ISLANDS
ALKALINE EARTH ISOTOPES
BASALT
CHEMISTRY
CONTINENTAL CRUST
CRYSTALLIZATION
EARTH CRUST
FEDERAL REGION X
GEOCHEMISTRY
GEOLOGIC FORMATIONS
GEOLOGY
IGNEOUS ROCKS
ISLANDS
ISOTOPE RATIO
ISOTOPES
MAGMA
NORTH AMERICA
ORIGIN
PETROLOGY
PHASE TRANSFORMATIONS
ROCKS
STRONTIUM ISOTOPES
TECTONICS
USA
VARIATIONS
VOLCANIC REGIONS
VOLCANIC ROCKS