Origin of zoning within dedolomite and calcitized gypsum of the Mississippian Arroyo Penasco Group
The Mississippian Arroyo Penasco Group carbonates are the oldest Paleozoic rocks present in north-central New Mexico. These supratidal to shallow,subtidal sediments exhibit complex diagenetic fabrics produced by periods of pre-Pennsylvanian subaerial exposure. Both extensive recrystallization of the Espiritu Santo carbonates and brecciation of the overlying Macho Member of the Tererro Formation resulted from an extended period of Mississippian subaerial exposure of broad, low-relief tidal flats. Cathodoluminescent petrography indicates that the recrystallized limestones consist of calcite pseudomorphs of dolomite and gypsum. Dedolomite and calcitized gypsum crystals, with /sup 13/C//sup 12/C ratios of -2 to +1.5% PDB, range from highly zoned to uniformly luminescent. Electron microprobe analyses reveals variable Mn and Fe contents across the pseudomorphs which are responsible for differences in observed luminosity. These features are interpreted to reflect a period of subaerial exposure after deposition of Macho Member sediments, which caused dissolution of gypsum and dolomite by sulfate and Mg depleted meteoric fluids and produced the collapse breccia. Preservation of zoning within some pseudomorphs required simultaneous dissolution of gypsum and dolomite and precipitation of calcite. C-isotope data indicates a meteoric to mixed phreatic origin for pore fluids which precipitated calcite; repetitive zoning within dolomite and gypsum pseudomorphs is indicative of interactions between marine and meteoric phreatic fluids in the intertidal environment.
- Research Organization:
- ARCO Exploration Company, Plano, TX (USA)
- OSTI ID:
- 6169655
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBONATE ROCKS
DIAGENESIS
PETROGRAPHY
DOLOMITE
PRECIPITATION
RECRYSTALLIZATION
NEW MEXICO
CALCITE
CARBON ISOTOPES
DISSOLUTION
GEOLOGIC FORMATIONS
GYPSUM
MISSISSIPPIAN PERIOD
ORIGIN
ZONES
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CALCIUM SULFATES
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
FEDERAL REGION VI
GEOLOGIC AGES
ISOTOPES
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
PALEOZOIC ERA
ROCKS
SEDIMENTARY ROCKS
SEPARATION PROCESSES
SULFATE MINERALS
SULFATES
SULFUR COMPOUNDS
USA
580300* - Mineralogy
Petrology
& Rock Mechanics- (-1989)