Geochemistry of dolomites in the St. Peter Sandstone of the Michigan Basin

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

OSTI ID:5808459

Winter, B L; Johnson, C M; Valley, J W ^[1]

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1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Geology and Geophysics

Quartz sandstone units in mid-continent sedimentary basins are considered to be major migration pathways for fluids throughout the history of such basins, possibly including connate and meteoric water, hydrocarbons, evaporite and basinal brines, and MVT ore-forming fluids. To gain an understanding of the fluid history of the Michigan Basin, the authors are investigating the dolomites in the St. Peter Sandstone. Based on petrography and lithofacies occurrence, they categorize the dolomites as: dolomite cement in quartz sandstone (DCS), replacive dolomite in carbonate-dominated intervals (RD), and fracture fill dolomite (FFD) associated with RD. RD and FFD display a linear covariation of mole %FeCO[sub 3] and Mn with Fe/Mn ratios increasing from 6 for bright orange luminescent RD to 11 for non-luminescent FFD. DCS display the highest %FeCO[sub 3] and no Fe-Mn correlation. DCS have higher ratios and SR concentrations than RD and FFD. Data for RD and FFD define two different, linear positive-sloping, Sr-87/Sr-86-%FeCO[sub 3] covariation trends. Samples with higher ratios and %FeCO[sub 3] have systematically lower [delta] O-18 values. Dolomites with Sr < 130ppm (mostly RD and FFD) follow the Sr-%MgCO[sub 3] trend defined by modern seawater dolomites; most of the DCS plot above this seawater dolomite trend. These data suggest that the RD and FFD precipitated from mid-Paleozoic seawater that progressively evolved in a basinal setting or mixed with an evolved basinal brine. DCS precipitated from a basinal brine that had interacted with rocks containing a significant amount of K-feldspar. The different correlation trends suggest heterogeneous water-rock interaction and isolated flow paths.

• OSTI ID: 5808459
• 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
ALKALINE EARTH ISOTOPES
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHEMISTRY
DEVELOPED COUNTRIES
DOLOMITE
ELEMENTS
GEOCHEMISTRY
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
HYDROGEN COMPOUNDS
IRON CARBONATES
IRON COMPOUNDS
ISOTOPE RATIO
ISOTOPES
MANGANESE
METALS
MICHIGAN
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
PETROGRAPHY
PRECIPITATION
ROCKS
SANDSTONES
SEAWATER
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SEPARATION PROCESSES
STRONTIUM ISOTOPES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
USA
WATER