Mineralization of organogenic ammonium in the Monterey Formation, Santa Maria and San Joaquin basins, California, USA
- Univ. of South Florida, St. Petersburg (United States)
- Louisiana State Univ., Baton Rouge (United States)
Inorganic fixed-ammonium (Amm) contents as high as 0.28 wt% were measured in organic-rich, quartz-grade siliceous rocks of the Miocene Monterey Formation from the Santa Maria and San Joaquin basins, California. The greatest amount of fixed-Amm was found in rocks associated with hydrocarbons in the Point Arguello and Lost Hills oil fields, where the Amm/(Amm + K) molar ratio of bulk samples ranges from 0.17-0.35. The formation of Amm-illite is suggested by the parallel increase in the percent of illite in the mixed-layered illite/smectite (I/S) and in the Amm/(Amm + K) molar ratio of the clay-sized fraction with increasing burial depth. Mineralization of Amm appears to be promoted by the coincident timing of the smectite-to-illite clay mineral transformation and the release of Amm during catagenesis. Amm-feldspar may form at shallow burial depths in rocks from the Point Arguello field that contain a greater amount of detrital K-feldspar and in which the I/S contains only 10-20% illite. Quartz-grade siliceous Monterey rocks from coastal outcrops in the Lions Head area lack significant amounts of hydrocarbons and have Amm/(Amm + K) molar ratios of 0.14-0.21. Rocks from the Lions Head area show a strong positive correlation between diagenetic illite and fixed-Amm contents, with Amm constituting 18-21 Mol% of the fixed interlayer cations in the I/S. The results of this study support the suggestion of Williams et al. (1989) that high fixed-Amm contents may provide a long-term geologic record of low-temperature (<150C) Amm mineralization associated with hydrocarbon generation and migration.
- DOE Contract Number:
- FG05-87ER13748
- OSTI ID:
- 5125170
- Journal Information:
- Geochimica et Cosmochimica Acta; (United States), Vol. 56:5; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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EXPERIMENTAL DATA
GEOLOGIC FORMATIONS
HYDROCARBONS
ILLITE
MINERALS
ORGANIC COMPOUNDS
ORIGIN
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DEVELOPED COUNTRIES
DIMENSIONS
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
HYDRIDES
HYDROGEN COMPOUNDS
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MASS TRANSFER
METALS
MINERAL RESOURCES
NITROGEN COMPOUNDS
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USA
020200* - Petroleum- Reserves
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