Stratigraphic development and hydrothermal activity in the central western Cascade Range, Oregon
Journal Article
·
· Journal of Geophysical Research; (United States)
- Portland State Univ., Oregon (USA)
- Reed Coll., Portland, OR (USA)
- Pioneer Metals Corp., Ruidoso, NM (USA)
Two volcanic sequences bounded by erosional unconformities compose the stratigraphy of the North Santiam mining district, Western Cascade Range, Oregon. Diorite, grandodiorite, and leucocratic quartz porphyry dikes, stocks, and sills intrude the breccias, flows, and tuffs of a volcanic center in the older Sardine Formation. Tourmaline-bearing breccia pipes are associated with the porphyritic granodiorite intrusions. An erosional unconformity separates the Sardine Formation from the overlying Elk Lake formation. The alteration patterns in the two formations are consistent with the development of hydrothermal systems during the eruption of each formation. However, the development of the two hydrothermal systems is separated by a period of erosion of the older volcanic pile. Early formation of mineralization that resembles porphyry copper deposits occurred within the Sardine Formation, and later, after eruption of the Elk Lake formation, epithermal veins and alteration developed along faults, fractures, and the margins of dikes in the Sardine Formation.
- OSTI ID:
- 5290771
- Journal Information:
- Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95:B12; ISSN 0148-0227; ISSN JGREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
15 GEOTHERMAL ENERGY
150200* -- Geology & Hydrology of Geothermal Systems
58 GEOSCIENCES
580000 -- Geosciences
CASCADE MOUNTAINS
DEVELOPED COUNTRIES
DIKES
ENERGY SYSTEMS
EROSION
EXTRUSION
FABRICATION
FEDERAL REGION X
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGY
GEOTHERMAL SYSTEMS
HYDROTHERMAL ALTERATION
HYDROTHERMAL SYSTEMS
IGNEOUS ROCKS
MATERIALS WORKING
MINERALIZATION
MOUNTAINS
NORTH AMERICA
OREGON
ROCKS
STRATIGRAPHY
USA
VOLCANIC REGIONS
VOLCANIC ROCKS
150200* -- Geology & Hydrology of Geothermal Systems
58 GEOSCIENCES
580000 -- Geosciences
CASCADE MOUNTAINS
DEVELOPED COUNTRIES
DIKES
ENERGY SYSTEMS
EROSION
EXTRUSION
FABRICATION
FEDERAL REGION X
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGY
GEOTHERMAL SYSTEMS
HYDROTHERMAL ALTERATION
HYDROTHERMAL SYSTEMS
IGNEOUS ROCKS
MATERIALS WORKING
MINERALIZATION
MOUNTAINS
NORTH AMERICA
OREGON
ROCKS
STRATIGRAPHY
USA
VOLCANIC REGIONS
VOLCANIC ROCKS