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Regional cementation from unconformity-recharged aquifer and burial fluids, Mississippian Newman Limestone, Kentucky

James C. Niemann and J. F. Read
Regional cementation from unconformity-recharged aquifer and burial fluids, Mississippian Newman Limestone, Kentucky
Journal of Sedimentary Petrology (July 1988) 58 (4): 688-705


The Mississippian Newman Limestone in Kentucky was studied to assess the effects of unconformities within and above the sequence on calcite cementation. Early cements are low in Fe and show a nonluminescent to dull to nonluminescent zonation. Early nonluminescent cement mainly formed in updip areas from oxidizing, meteoric waters in a regional paleoaquifer that formed during regional regression in the Late Mississippian. During Late Mississippian transgression, waters became reducing to form early dull cement (up to 600 ppm Mn, up to 2,700 ppm Fe but averaging 570 ppm). The aquifer underwent later recharge during Mississippian-Pennsylvanian regression to form a second nonluminescent cement. This event continued into the Pennsylvanian when the sequence underwent increasing burial. Early cements have delta (super 13) O values that become lighter downdip, perhaps reflecting a downdip temperature increase due to burial. delta (super 13) C values are lightest in the north (postulated recharge area) and reflect input of organically derived CO (sub 2) in waters there. Most calcite cementation appears to have been associated with two post-Newman unconformities which generated regional aquifers and reflects a shift to a wetter climate in Late Mississippian-Pennsylvanian time. Early cement abundance decreases away from postulated recharge areas. Later iron-rich burial cements (up to 2,200 ppm Mn, up to 11,000 ppm Fe) fill remaining pore spaces, compaction-induced fractures, spalled cement rims, and tectonic fractures lined with saddle dolomite and pyrite. They formed above 60 degrees C at depths of 1 to 3 km. delta (super 13) O values are compatible with derivation by pressure solution of preexisting calcites in isotopically heavy waters highly modified by burial diagenesis. Light delta (super 13) C values reflect isotopically light organic carbon in the deltaic waters entering the subsurface, or being expelled from shales or buffering of waters by light C, early calcite cements. The delta (super 13) C calcite cements become heavier downdip by equilibration of waters with host limestone. Newman sediments may have been subjected to late, postcementation(?) migration of warm fluids based on secondary fluid inclusions. These late-stage fluids most likely were chemically complex, warm brines (7-17 equiv. wt. % NaCI, 50 degrees to 160 degrees C) that resided in the formation for sufficiently short times that conodont CAI values were not affected.

ISSN: 0022-4472
Serial Title: Journal of Sedimentary Petrology
Serial Volume: 58
Serial Issue: 4
Title: Regional cementation from unconformity-recharged aquifer and burial fluids, Mississippian Newman Limestone, Kentucky
Affiliation: Chevron U.S.A., New Orleans, LA, United States
Pages: 688-705
Published: 198807
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 57
Accession Number: 1988-059175
Categories: Sedimentary petrologyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sects., strat. col., sketch maps
N37°00'00" - N38°49'60", W85°00'00" - W83°00'00"
Secondary Affiliation: Va. Polytech. Inst. and State Univ., USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1988
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