Drilling investigation of a young magmatic intrusion beneath the Inyo Domes, Long Valley, California: Structural and textural studies:
The purpose of this project was to characterize the geometry and emplacement mechanisms of silicic dikes beneath the Inyo Domes, California. The investigation involved surface structural and textural studies in the Inyo area, mapping projects in analogous areas that offered better controls on either the three-dimensional geometry or emplacement conditions of dikes, and analytical studies of drill core samples. Mapping of structures on and around the Domes suggested that they were fed by an echelon arrangement of rotated dike segments, as later confirmed by the drill cores, and that the dike propagated obliquely to the north. A model was derived relating dike segmentation to changes in host-rock rheology and fracture behavior, rather than to variations in principle stress orientations. Studies of eroded volcanoes showed that the rotation of segments and host-rock brecciation both increase as a dike approaches the surface. SEM and isotopic studies of drill cores led to a model for volatile migration within advancing silicic flows which predicts that explosive hazards associated with these flows may increase as the flow gets farther from its vent. A new model for selective withdrawal from a stratified dike explained observed compositional and textural variations within and among the three Inyo Domes. 11 refs.
- Research Organization:
- Arizona State Univ., Tempe (USA)
- DOE Contract Number:
- FG02-85ER13320
- OSTI ID:
- 5237293
- Report Number(s):
- DOE/ER/13320-1; ON: DE88006613
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580202* -- Geophysics-- Volcanology-- (1980-1989)
CALDERAS
CALIFORNIA
DIKES
DOCUMENT TYPES
DRILL CORES
ELECTRON MICROSCOPY
EMPLACEMENT
FEDERAL REGION IX
FORECASTING
GEOLOGIC STRUCTURES
LONG VALLEY
MAPPING
MATHEMATICAL MODELS
MICROSCOPY
NORTH AMERICA
OXYGEN COMPOUNDS
PROGRESS REPORT
SCANNING ELECTRON MICROSCOPY
SILICATES
SILICON COMPOUNDS
TEXTURE
USA