Regional diagenesis of sandstone in the Upper Jurassic Morrison Formation, San Juan Basin, New Mexico and Colorado

Book · Mon Jan 01 04:00:00 EST 1990

OSTI ID:6440578

Hansley, P L

The author reports that early authigenic mineral assemblages and vitroclastic textures are very well preserved in upper sandstones of the Upper Jurassic Morrison Formation. The distributions of the authigenic minerals were controlled, in part, by chemical gradients in a large saline, alkaline lake (Lake T'oo'dichi) that existed in late Morrison time. Sandstones on lake margins were cemented by smectite and silica, whereas sandstones nearer the lake center, in which waters were most saline and alkaline, were cemented by zeolites. Diagenetic alterations in sandstones were promoted by alkaline interstitial waters that emanated from adjacent fine-grained, tuffaceous lake beds. Metastable phases that precipitated first were replaced relatively quickly by more stable, ordered phases in the geochemically favorable environment of the closed basin setting. Elevation of temperatures above the geothermal gradient was proved by the influx of warm, deep-basin waters that locally modified early diagenetic assemblages during burial diagenesis. In organic- (and commonly also uranium ore-) bearing sandstones located primarily in the southern part of the basin, complex diagenetic assemblages resulted from water/rock reactions involving soluble organic complexes.

• OSTI ID: 6440578
• Country of Publication: United States
• Language: English

Related Subjects

050100* -- Nuclear Fuels-- Reserves
Exploration
& Mining
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
CHEMISTRY
COLORADO
DIAGENESIS
EXPLORATION
FEDERAL REGION VI
FEDERAL REGION VIII
GEOCHEMISTRY
GEOLOGIC DEPOSITS
KINETICS
MINERAL RESOURCES
NEW MEXICO
NORTH AMERICA
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
URANIUM DEPOSITS
USA