Investigations of the Dunes geothermal anomaly, Imperial Valley, California. Part III. Further petrological studies. Hydrothermal alteration and mass transfer in the discarge portion of the Dunes geothermal system, Imperial Valley of California, USA

Technical Report · Sun Jun 01 04:00:00 EDT 1975

OSTI ID:7228211

Bird, D K; Elders, W A

This study concerns self-sealing in stratigraphically-controlled sedimentary aquifers in the discharge portion of a hydrothermal system, located at the Southeast margin of the Salton Trough. Intense low-temperature hydrothermal alteration of deltaic sediments of the Colorado River occurs in this discharge portion. The aquifers are stratigraphically controlled with seven zones of intensively silicified quartzites developed in the upper 318 m. Shale beds of low permeability separate these silicified horizons from poorly indurated sandstones which are cemented by varying amounts of hematite, calcite, gypsum and montmorillonoid clays. The silicified zones were formed in what were originally much more permeable sandstones and conglomerates. Hydrothermally altered sands have a net chemical gain of SiO/sup 2/ and K/sup 2/O, and loss of CaO, Na/sup 2/O, FeO, and MgO, relative to unaltered surface sands, due to reaction with silica-saturated hydrothermal solutions having a high K+/H+ activity ratio. Hot brines migrated laterally rather than vertically through the formation. Hydrothermal metasomatism reduced the permeability of the aquifers forming a dense cap-rock which modified the hydrology and provided a geophysical exploration target.

• Research Organization: California Univ., Riverside (USA). Inst. of Geophysics and Planetary Physics
• OSTI ID: 7228211
• Report Number(s): PB-259818; IGPP-UCR-75-14
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
152003* -- Geothermal Data & Theory-- Rock-Water-Gas Interactions
ALKALINE EARTH METAL COMPOUNDS
AQUIFERS
BRINES
CALCITE
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CALCIUM SULFATES
CALIFORNIA
CARBON COMPOUNDS
CARBONATES
CHALCOGENIDES
CLAYS
COLORADO RIVER
EXPLORATION
GEOLOGICAL SURVEYS
GEOLOGY
GEOTHERMAL EXPLORATION
GEOTHERMAL FIELDS
GEOTHERMAL SYSTEMS
GYPSUM
HEMATITE
HYDROTHERMAL ALTERATION
HYDROTHERMAL SYSTEMS
IMPERIAL VALLEY
IRON COMPOUNDS
IRON ORES
IRON OXIDES
MASS TRANSFER
METAMORPHIC ROCKS
MINERALS
NORTH AMERICA
ORES
OXIDES
OXYGEN COMPOUNDS
PERMEABILITY
PETROLOGY
QUARTZITES
RIVERS
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SHALES
STREAMS
SULFATES
SULFUR COMPOUNDS
SURFACE WATERS
THERMAL WATERS
TRANSITION ELEMENT COMPOUNDS
USA
WESTERN REGION