Multiple origins for zoned cathodoluminescent and noncathodoluminescent calcite cements in Pennsylvanian limestones
- Univ. of Kansas, Lawrence (United States)
Noncathodoluminescent calcite containing brightly to moderately luminescent zones is a common early cement in limestones. Three such cements in Upper Pennsylvanian limestones from different areas were studied. All three units are overlain up-section by Permian evaporites and consist of carbonate-siliciclastic 'cyclothems' in which individual cycles were subject to subaerial exposure. With such similar settings, one might predict that petrographically similar calcite cements would have similar origins. In the Holder Formation (New Mexico), the zoned calcite predates compaction, and cross-cutting relationships with cycle-capping paleosols show that zoned cements precipitated during 15 events of subaerial exposure. Therefore, cements precipitated from freshwater during early and repeated subaerial exposure. For the Lansing-Kansas City groups in northwestern Kansas, the zoned calcite cements commonly are among the first precipitated but may postdate some compaction. All-liquid fluid inclusions indicated precipitation below about 50C, from brines of approximately 23 weight %. NaCl equivalent. The brines may have refluxed downward during deposition of Permian evaporites. A limestone of the Lansing-Kansas City groups of west-central Kansas contains early zoned calcite cement that predates compaction. The cement contains all-liquid fluid inclusions indicating precipitation below about 50C. The presence of nonluminescent calcite containing bright subzones is not indicative of a single diagenetic environment. Petrographically similar cements from similar settings may originate in markedly different diagenetic environments.
- OSTI ID:
- 5677360
- Report Number(s):
- CONF-910403--
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 75:3; ISSN AABUD; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
CALCITE
CARBONATE MINERALS
CARBONATE ROCKS
CARBONIFEROUS PERIOD
CATHODOLUMINESCENCE
COMPARATIVE EVALUATIONS
DEVELOPED COUNTRIES
DIAGENESIS
EVALUATION
FEDERAL REGION VI
FEDERAL REGION VII
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GROUND WATER
HYDROGEN COMPOUNDS
INTERSTITIAL WATER
KANSAS
LIMESTONE
LUMINESCENCE
MINERALIZATION
MINERALOGY
MINERALS
NEW MEXICO
NORTH AMERICA
ORIGIN
OXYGEN COMPOUNDS
PALEOZOIC ERA
PRECIPITATION
ROCK-FLUID INTERACTIONS
ROCKS
SEDIMENTARY ROCKS
SEPARATION PROCESSES
USA
WATER