Controls on the water chemistry of some springs in a volcanic terrain, Nayarit, Mexico
Dissolution and alteration of minerals and glass in fresh rock, and the extensive occurrence of amorphous residues and precipitates in the weathered rock, control the spring water composition of two volcanoes located in the northwestern segment of the Mexican Volcanic Belt. SEM photomicrographs reveal dissolution and alteration features on phenocrysts that include crystallographically oriented etch pits, and high Al and Fe residues. Vessicles in glass appear to be coalescing to form large voids. Amorphous products are Al-Fe-Si oxides and hydroxides and include allophane and other pseudo-crystalline products. No clay minerals occur in concentrations above the detection limit of an XRD. Silica, sodium and potassium are released into solution at the fresh rock/weathered rock interface. Silica appears to reach a maximum of 100 ppm due to buffering by amorphous silica precipitates. Sinks for potassium may occur deep in the weathering profile on some rock types as Na/K released upon weathering is significantly lower than that found in solution. The anomolously high concentrations of magnesium and calcium in the groundwater and weathered rock, is an indication that they are being released along the flow path and may be adsorbed onto clay-size material where the water emerges through the soil zone.
- Research Organization:
- Tulane Univ., New Orleans, LA (USA)
- OSTI ID:
- 6321307
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MEXICO
VOLCANIC REGIONS
WATER SPRINGS
VOLCANIC ROCKS
DISSOLUTION
HYDROTHERMAL ALTERATION
WATER CHEMISTRY
CALCIUM COMPOUNDS
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CLAYS
CRYSTALLOGRAPHY
GEOCHEMISTRY
GROUND WATER
MAGNESIUM COMPOUNDS
SCANNING ELECTRON MICROSCOPY
VOLCANOES
X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS
CHEMISTRY
COHERENT SCATTERING
DEVELOPING COUNTRIES
DIFFRACTION
ELECTRON MICROSCOPY
HYDROGEN COMPOUNDS
IGNEOUS ROCKS
LATIN AMERICA
MICROSCOPY
NORTH AMERICA
OXYGEN COMPOUNDS
ROCKS
SCATTERING
WATER
580100* - Geology & Hydrology- (-1989)
580400 - Geochemistry- (-1989)