Formation waters from Mississippian-Pennsylvanian reservoirs, Illinois basin, USA: Chemical and isotopic constraints on evolution and migration

Journal Article · Mon Feb 01 00:00:00 EST 1993 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(93)90167-U· OSTI ID:6890096

Stueber, A M ^[1]; Walter, L M; Huston, T J ^[2]; Pushkar, P ^[3]

---

1. Southern Illinois Univ., Edwardsville (United States)
2. Univ. of Michigan, Ann Arbor (United States)
3. Wright State Univ., Dayton, OH (United States)

We have analyzed a suite of seventy-four formation-water samples from Mississippian and Pennsylvanian carbonate and siliciclastic strata in the Illinois basin for major, minor, and trace element concentrations and for strontium isotopic composition. A subset of these samples was also analyzed for boron isotopic composition. Data are used to interpret origin of salinity and chemical and Sr isotopic evolution of the brines and in comparison with a similar data set from an earlier study of basin formation waters from Silurian-Devonian reservoirs. Systematics of Cl-Br-Na show that present Mississippian-Pennsylvanian brine salinity can be explained by a combination of subaerial seawater evaporation short of halite saturation and subsurface dissolution of halite from an evaporite zone in the middle Mississippian St. Louis Limestone, along with extensive dilution by mixing with meteoric waters. Additional diagenetic modifications in the subsurface interpreted from cation/Br ratios include K depletion through interaction with clay minerals, Ca enrichment, and Mg depletion by dolomitization, and Sr enrichment through CaCO[sub 3] recrystallization and dolomitization. Ste. Genevieve Limestone (middle Mississippian) formation waters show [sup 87]Sr/[sup 86]Sr ratios in the range 0.70782-0.70900, whereas waters from the siliciclastic reservoirs are in the rante 0.70900-0.71052. Inverse correlations between [sup 87]Sr/[sup 86]Sr and B,Li, and Mg concentrations suggest that the brines acquired radiogenic [sup 87]Sr through interaction with siliciclastic minerals. Completely unsystematic relations between [sup 87]Fr/[sup 86]Sr and 1/Sr are observed; Sr concentrations in Ste. Genevieve and Aux Vases (middle Mississippian) waters appear to be buffered by equilibrium with respect to SrSo[sub 4]. These formation waters are distinguished from Silurian-Devonian brines in the basin by elevated Cl/Br and Na/Br ratios and by unsystematic Sr isotope relationships.

• OSTI ID: 6890096
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 57:4; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
02 PETROLEUM
FLUIDS
ENVIRONMENTAL TRANSPORT
STRONTIUM 86
ISOTOPE RATIO
STRONTIUM 87
BORON
BRINES
CARBONIFEROUS PERIOD
CONSTRAINTS
CORRELATIONS
DEVONIAN PERIOD
DIAGENESIS
DILUTION
DISSOLUTION
ENRICHMENT
EQUILIBRIUM
EVAPORATION
HALITE
ILLINOIS BASIN
LIMESTONE
LITHIUM
MAGNESIUM
MINERALS
MIXING
MODIFICATIONS
ORIGIN
RANGE
RECRYSTALLIZATION
SALINITY
SATURATION
SEAWATER
SILURIAN PERIOD
STRONTIUM
ALKALI METALS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
BETA DECAY RADIOISOTOPES
CARBONATE ROCKS
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC AGES
HALIDE MINERALS
HOURS LIVING RADIOISOTOPES
HYDROGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MASS TRANSFER
METALS
NUCLEI
OXYGEN COMPOUNDS
PALEOZOIC ERA
PHASE TRANSFORMATIONS
RADIOISOTOPES
ROCKS
SEDIMENTARY ROCKS
SEMIMETALS
STABLE ISOTOPES
STRONTIUM ISOTOPES
WATER
400100* - Analytical & Separations Chemistry
020200 - Petroleum- Reserves
Geology
& Exploration