Dissimilar diagenetic histories of Jurassic sandstones in the Gulf of Mexico

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5591246

Dworkin, S I ^[1]

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1. Baylor Univ., Waco, TX (United States). Dept. of Geology

Jurassic sandstones from the LA and MS interior salt basins show different diagenetic histories apparent from the style of framework grain modification, the types of cements precipitated, and the timing of cementation. Differences in diagenetic histories can be attributed to the depositional environment of the sandstones as well as the subsequent evolution of the pore fluids. Feldspars within the sandstones in the two basins show contrasting compositions resulting from diagenesis rather than provenance. Sandstones in the LA basin contain feldspars with end-member albite compositions, whereas the feldspars in the MS basin are dominated by end-member K-feldspar compositions. Potassium-rich brines in the MS basin, which provided the chemical stability for those feldspars, were probably generated through the dissolution of deeply buried bittern salts. The paragenetic sequence for the major cementation events in the LA basin sandstones is quartz, ferroan dolomite, calcite, and anhydrite. The order of cement precipitation in the MS basin is K-feldspar, dolomite, quartz, calcite, and anhydrite. The early dolomite in the MS basin has a composition indicative of a seawater origin and is missing from the LA basin because LA basin sandstones were deposited in deep water and thus lacked an efficient pump. Quartz cement in both basins has oxygen isotopic compositions that indicate relatively early emplacement although the timing of this cement in the two basins differs. The origin of silica for the quartz is inferred to be from dissolving feldspars during shallow burial. The presence of ferroan dolomite in the LA basin indicates that the evolution of the pore fluids continued to vary between the basins late in the burial history. Anhydrite cementation occurred in both basins late in the burial history as a result of remobilization of buried calcium sulfate deposits.

• OSTI ID: 5591246
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
ATLANTIC OCEAN
BRINES
CARIBBEAN SEA
CHEMISTRY
DEVELOPED COUNTRIES
DIAGENESIS
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GULF OF MEXICO
JURASSIC PERIOD
LOUISIANA
MESOZOIC ERA
MINERALOGY
MISSISSIPPI
NORTH AMERICA
PARAGENESIS
ROCKS
SALT DEPOSITS
SANDSTONES
SEAS
SEDIMENTARY ROCKS
SURFACE WATERS
USA