Early-to-late-diagenetic dolomitization of platform carbonates: Lower Ordovician Ellenburger Group, Permian basin, west Texas and southeastern New Mexico
- McGill Univ., Montreal, Quebec (Canada)
- City Univ. of New York, NY (United States) Northeastern Science Foundation, Troy, NY (United States)
Pervasive early- to late-diagenetic dolomitization of Lower Ordovician Ellenburger carbonates in the deep Permian basin is recorded in core samples having present-day burial depths of 1.5 to 7.0 km. Fine-crystalline planar replacement dolomite formed during early diagenesis in a subtidal to peritidal setting under near-surface, low-temperature conditions, with Mg{sup 2+} for dolomitization of precursor lime mud supplied by diffusion from overlying seawater. During intermediate burial (500-2,000 m), medium- to coarse-crystalline planar-s dolomite replaced allochems and matrix, or occurred as void-filling. Burial-history and thermal maturation calculations suggest that deep-burial dolomite cementation occurred during the Late Pennsylvanian/Early Permian. Inter- and intracrystalline dissolution surfaces are observed within the paragenetic sequence. Major truncation surfaces between early replacement dolomites and later void-filling dolomites, and between planar and nonplanar dolomite cements are evidence for dolomite dissolution. Deep-discharge of meteoric fluids as a result of frequent periods of karsting in overlying strata, and long-distance fluid migration during the Ouachita orogeny from foreland basins to the south are invoked for sources of undersaturated fluids causing dolomite dissolution and creating matrix-porosity in the deep subsurface. Similar diagenetic relationships have been described from other deeply buried carbonate rocks elsewhere, indicating that trends and timing of dolomitization, dissolution and porosity formation, and cementation by late dolomite and calcite are intimately related to the evolution of sedimentary basins. The origin of massive dolostones such as the Ellenburger is best explained in the context of basin evolution, rather than by a single model of dolomite formation.
- OSTI ID:
- 5862911
- 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
BUILDING MATERIALS
CALCITE
CARBONATE MINERALS
CARBONATE ROCKS
CEMENTS
CRYSTAL STRUCTURE
DEVELOPED COUNTRIES
DIAGENESIS
DISSOLUTION
DOLOMITE
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
MATERIALS
MICROSTRUCTURE
MINERALS
NEW MEXICO
NORTH AMERICA
ORDOVICIAN PERIOD
OXIDE MINERALS
PALEOZOIC ERA
PARAGENESIS
PERMIAN BASIN
POROSITY
QUARTZ
ROCKS
SEDIMENTARY ROCKS
TEXAS
USA