Compositional variation of late dolomite cement as a guide to parent fluid flow directions in the Cambrian Bonneterre Formation, Missouri
Oxygen isotopic composition and strontium concentrations in host dolomite indicate extensive modification of initial dolomite by isotopically light fluids or fluids at above surface temperatures. The dolomite precursor to light-colored fine-crystalline dolomite (LF) spatially associated with Precambrian highlands probably formed in the supratidal environment. The precursor to dark-colored, fine- to medium-crystalline dolomite (DF), which occurs primarily within subtidal facies, formed in the shallow subsurface from marine-dominated pore fluids. Light-colored coarse-crystalline dolomite (LC) replaces both LF and DF dolomite and its distribution appears to be controlled by preexisting high porosity adjacent to Precambrian highs. Ferroan dolomite (FR) from the basal Bonneterre Formation dolomite replaces both preexisting non-ferroan dolomite and limestone. The iron and Mn in FR dolomite was apparently derived locally from clay minerals in the section during moderate burial. A luminescent microstratigraphy within dolomite cement can be correlated throughout southern Missouri. Iron content is the major control on luminescence. The repetitive minor element variation and presence of unconformities within the cement are consistent with the growth bands forming from cyclical pulses of fluids from one of the surrounding sedimentary basins. Covariation of [delta][sup 18]O, [sup 87]Sr/[sup 86]Sr, Fe, Mn, and Sr within dolomite cement suggests that host rock buffering was an important control on composition of the parent fluids. There is a southeast to northwest decrease in [sup 87]Sr/[sup 86]Sr and increase in [delta][sup 18]O within zone 4 cement in the lower Bonneterre suggesting that parent fluids entered the region primarily from the southeast.
- Research Organization:
- Texas Univ., Austin, TX (United States)
- OSTI ID:
- 6789464
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
ALKALINE EARTH ISOTOPES
CARBONATE MINERALS
CHEMICAL COMPOSITION
CHEMISTRY
CLAYS
COLOR
COMPUTERIZED SIMULATION
DEVELOPED COUNTRIES
DISTRIBUTION
DOLOMITE
ELEMENTS
FEDERAL REGION VII
FLUID FLOW
FLUIDS
GEOCHEMISTRY
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
HYDROLOGY
IRON
ISOTOPES
LUMINESCENCE
MANGANESE
METALS
MINERALS
MISSOURI
NORTH AMERICA
OPTICAL PROPERTIES
ORGANOLEPTIC PROPERTIES
OXYGEN ISOTOPES
PHYSICAL PROPERTIES
POROSITY
RESERVOIR FLUIDS
RESERVOIR TEMPERATURE
SEDIMENTARY BASINS
SIMULATION
STRATIGRAPHY
STRONTIUM ISOTOPES
TRANSITION ELEMENTS
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