Stylolites in the Upper Smackover Formation of north Louisiana

Conference · Tue May 01 04:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6729733

Denham, M E; Tieh, T T ^[1]

---

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

Stylolites may be more intimately related to the late stages of diagenesis in carbonate rocks than previously believed. Petrographic and fission track studies of stylolites in subsurface cores of upper Smackover rocks suggest that some of these features may have acted as conduits for late-stage pore fluids and thus have played an active role in the late-stage diagenesis of these rocks. Stylolites are abundant in the rocks studied, ranging in size from microstylolites - grain to grain sutures - to stylolites a millimeter thick with amplitudes of a centimeter or more. In some of the coarser grainstones, networks of microstylolites have formed that eventually connect to larger stylolites. Late-stage authigenic phases are present within many of the stylolites. In some stylolites the high abundance of pyrite requires that some was precipitated during or after stylolite formation. Likewise, sphalerite, a common late-stage authigenic mineral, is present in some stylolites. Dolomite rhombs and anhydrite are also associated with stylolites in these samples. The occurrence of anhydrite is suggestive of late-stage fluid flow along stylolites. Anhydrite replaces the dolomite rhombs, as well B micritized grains within and around stylolites. The degree of the replacement varies from a few anhydrite crystals along a stylolite to large (several centimeters) anhydrite nodules containing traces of dolomite and stylolite-filling organics. Fission-track studies reveal that uranium is enriched in stylolite compared to their host rocks. Fission-track densities of two stylolite show their minimum uranium concentrations to be 35 and 60 ppm respectively, compared to host rock concentrations of 1-3 ppm. This enrichment of uranium may result from the migration along stylolites of uranium-rich fluids associated with hydrocarbon maturation.

• OSTI ID: 6729733
• Report Number(s): CONF-900605--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 74:5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580000 -- Geosciences
ALKALINE EARTH METAL COMPOUNDS
CALCITE
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATE ROCKS
CARBONATES
DIAGENESIS
DOLOMITE
FEDERAL REGION VI
FISSION TRACKS
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
LOUISIANA
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERAL RESOURCES
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
PARTICLE TRACKS
PETROGRAPHY
PETROLEUM DEPOSITS
RESERVOIR ROCK
RESOURCES
ROCKS
SEDIMENTARY ROCKS
USA