The association of calcite veins with stylolites in the Smackover Formation of north Louisiana

Conference · Fri Mar 01 04:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5682174

Denham, M E; Tieh, T T ^[1]

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1. Texas A and M Univ., College Station (United States)

Small calcite veins in the grainstones of the Upper Smackover Formation of north Louisiana provide insight into the role of stylolites in the late stages of diagenesis of these carbonate rocks. The veins always occur in groups, ranging from a few to swarms. In the two cores examined, vein widths varied from 5 {mu}m to 1 mm and lengths varied from 100 {mu}m to several millimeters. Most veins have one end that terminates at a stylolite; some have both ends terminated by stylolites. The same vein never appears on both sides of a large stylolite, although some veins do cut smaller stylolites. Sets of parallel veins occur at angles to each other in the same swarm - one set cutting the other. The original mineralogy of the veins is calcite. It appears lenticular in thin-section with the long axis of the grains perpendicular to the vein length. Preliminary electron microprobe analyses show the calcite to be relatively pure, containing less than 1% by weight MgCO{sub 3}. However, the calcite does contain slightly more iron than the surrounding micritic matrix. Anhydrite and dolomite frequently replace the calcite in the vein. This replacement generally occurs at the terminus of a vein in a stylolite. Dissolution of the calcite in the veins to produce fracture porosity is also common. The veins are remnants of localized episodic fluid pressure increases that occurred during the latter stages of diagenesis of the Smackover. The same process that formed the veins may have opened the stylolites to fluids that caused the replacement of the veins as well as the later creation of secondary porosity.

• OSTI ID: 5682174
• Report Number(s): CONF-910403--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 75:3
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580000 -- Geosciences
CALCITE
CARBONATE MINERALS
CARBONATE ROCKS
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
DEVELOPED COUNTRIES
DIAGENESIS
DISSOLUTION
ELECTRON MICROPROBE ANALYSIS
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
JURASSIC PERIOD
LOUISIANA
MESOZOIC ERA
MICROANALYSIS
MINERAL RESOURCES
MINERALOGY
MINERALS
NONDESTRUCTIVE ANALYSIS
NORTH AMERICA
PETROLEUM DEPOSITS
POROSITY
RESERVOIR ROCK
RESOURCES
ROCKS
SEDIMENTARY ROCKS
USA