Geology and geochemistry of the Dunes Hydrothermal System, Imperial Valley of California

Technical Report · Sat Mar 01 04:00:00 EDT 1975

OSTI ID:7217194

Bird, D K

The Dunes hydrothermal system is located near the southeast basin margin of the Salton Trough structural rift in southern California. Intense potassium and silica metasomatism is associated with hydrothermal alteration of lateral clastic aquifers in the discharge portion of this hydrothermal system. The rocks recovered are terrigenous detritus of the Colorado River delta, and consist primarily of sands with highly uniform mineralogical composition. Four distinct sedimentary facies are present, including deltaic sand, channel fill, braided stream-dune, and lacustrine facies. Diagenetic alteration has produced poorly indurated sediments cemented by varying amounts of hematite, calcite, gypsum, and montmorillonoid clays. Potassium silicate hydrothermal alteration, characterized by authigenic quartz, adularia, pyrite, and hydromuscovite, has occurred within seven intervals (5 to 35 meters thick) of permeable strata of the channel fill and braided stream-dune facies. The resultant rocks are dense, vitreous, sublithic quartzites with densities as high as 2.55 gm/cc and porosities as low as 3-4%. Hydrothermally altered sands have a net chemical gain of SIO/sub 2/ and K2O, and loss of CaO, Na/sub 2/O, FeO, and MgO, in comparison with unaltered surface sands. (GRA)

• Research Organization: California Univ., Riverside (USA). Inst. of Geophysics and Planetary Physics
• OSTI ID: 7217194
• Report Number(s): PB-258098; IGPP-UCR-75-2
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
152002* -- Geothermal Data & Theory-- Properties of Minerals & Rocks
152003 -- Geothermal Data & Theory-- Rock-Water-Gas Interactions
AQUIFERS
CALIFORNIA
CHEMISTRY
CLAYS
DIAGENESIS
GEOCHEMISTRY
GEOLOGY
GEOTHERMAL SYSTEMS
HYDROTHERMAL ALTERATION
HYDROTHERMAL SYSTEMS
IMPERIAL VALLEY
MINERALOGY
MINERALS
NORTH AMERICA
USA
WESTERN REGION