Petrographic and geochemical constraints on the formation and diagenesis of anhydrite cements, Smackover sandstones, Gulf of Mexico

Journal Article · Fri Apr 01 00:00:00 EST 1994 · Journal of Sedimentary Research - Section A; (United States)

OSTI ID:7048033

Dworkin, S I ^[1]; Land, L S ^[2]

---

1. Baylor Univ., Waco, TX (United States). Dept. of Geology
2. Univ. of Texas, Austin, TX (United States). Dept. of Geological Sciences

Anhydrite cement is common in sedimentary rocks, yet its origin is poorly understood. The high concentration of sulfate in sea water and the lack of appreciable sulfate in most other natural waters suggests that anhydrite cement may have a marine origin, but the relatively late timing of most anhydrite cement tends to preclude sea water as the source of sulfate. Anhydrite cement is present in Upper Jurassic sandstones in the Gulf of Mexico as poikilotopic masses in which detrital grains are replaced and as smaller patches that have replaced single detrital grains. Anhydrite is a relatively late cement and postdates all other volumetrically significant authigenic phases, including K-feldspar, dolomite, quartz, and most calcite cements. The expected isotopic composition and trace-element concentration of marine-derived Late Jurassic anhydrite cement is predicted based on analyses of bedded anhydrite and on analyses found in literature. The expected chemical signature is: [delta][sup 34]S ([per thousand]CDT) = +16, [delta][sup 18]O ([per thousand]SMOW) = +14, [sup 87]Sr/[sup 86]Sr = 0.7069, Sr = 1500--2500 ppm, Ba < 20 ppm, and Mg > 200 ppm. When geochemical analyses of Smackover anhydrite cements are compared to the predicted composition, it is apparent that most of the cement is not of marine origin. The chemistry of Louisiana and Mississippi basin anhydrite cements indicates that the sulfate was derived from dissolved bedded anhydrite and was reprecipitated in the sandstones from fluids that had undergone extensive water-rock interaction after considerable burial. This study suggests that late anhydrite cements in sedimentary rocks are most likely derived from remobilized calcium sulfate deposits.

• OSTI ID: 7048033
• Journal Information: Journal of Sedimentary Research - Section A; (United States), Vol. A64:2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
58 GEOSCIENCES
ANHYDRITE
ISOTOPE RATIO
ORIGIN
GULF OF MEXICO
NATURAL GAS DEPOSITS
PETROLEUM DEPOSITS
RESERVOIR ROCK
DIAGENESIS
GEOCHEMISTRY
PETROGRAPHY
GEOLOGIC FORMATIONS
ATLANTIC OCEAN
CARIBBEAN SEA
CHEMISTRY
GEOLOGIC DEPOSITS
GEOLOGY
MINERAL RESOURCES
MINERALS
RESOURCES
SEAS
SULFATE MINERALS
SURFACE WATERS
020200* - Petroleum- Reserves
Geology
&amp; Exploration
030200 - Natural Gas- Reserves
Geology
&amp; Exploration
580000 - Geosciences