Petrographic and geochemical constraints for fluid source and possible pathways during burial diagenesis of Maryville Limestone (M. Cambrian) southern Appalachians
- Univ. of Tennessee, Knoxville, TN (United States). Dept. of Geological Sciences
- Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Geology
Burial dolomitization of platform carbonates is often attributed to fluids derived from shale basins. This study focuses on the application of geochemistry to trace the direction of fluid flow and hypothesize about fluid source(s) during burial diagenesis of the Maryville Limestone. Petrographic analyses along a depositional transect from platform-margin to basin reveals that dolomite is the principal burial diagenetic phase. The authors have identified four different generations of dolomite based on petrographic and geochemical analyses. Type 1 dolomite occurs as irregular disseminations typically within mud rich facies. Type 2 dolomite typically occurs as inclusions of planar-euhedral rhombs (ferroan) 5 to 300 [mu] size in blocky clear ferroan calcite (meteoric) spar. Type 2 dolomite consists of non-luminescent rhombs under cathodoluminescence. Type 1 and 2 dolomites are interpreted to have formed during shallow-intermediate burial diagenesis. Type 3 dolomite consists of subhedral to anhedral crystals of approximately 10 [mu] to 150 [mu] size. It occurs as thin seams along stylolites and as thick bands measuring a few mm. Under cathodoluminescence the crystals are dominantly non-luminescent and less commonly show orange luminescence and zoning. Type 4 dolomite is baroque or saddle dolomite that occurs as non-luminescent, subhedral to anhedral crystals 100--1,500 [mu] size. Type 4 dolomite probably formed during maximum burial. Based on the Fe and Mn distributions in saddle dolomite, the authors propose a west-east fluid flow during late burial diagenesis. Depleted oxygen isotope compositions suggests that the fluids were warm. Presence of saddle dolomite confirms this conclusion. Similar Sr-isotope compositions for Type 3 and Type 4 dolomite suggest that they formed from fluid of similar composition. Finally enriched Sr-isotope ratio is consistent with a siliciclastic source for the fluids during deep burial.
- OSTI ID:
- 5878784
- Report Number(s):
- CONF-921058--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 24:7; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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58 GEOSCIENCES
580000* -- Geosciences
APPALACHIAN MOUNTAINS
CARBONATE MINERALS
CHEMISTRY
DIAGENESIS
DOLOMITE
ENVIRONMENTAL TRANSPORT
FLUIDS
GEOCHEMISTRY
GEOLOGIC STRUCTURES
GEOLOGY
LITHOLOGY
MASS TRANSFER
MINERALIZATION
MINERALS
MOUNTAINS
PETROGRAPHY
PETROLOGY
RESERVOIR FLUIDS
SEDIMENTARY BASINS