Vadose diagenesis of Quaternary eolianite sequences, San Salvador Island, Bahamas
Conference
·
· Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:5300968
Vadose alteration of eolian grainstone results in the formation of a characteristic vertical sequence of diagenetic fabrics. Eolianite sequences of San Salvador Island, Bahamas, are divided into zones of minor, moderate, and intense alteration. The zone of minor alteration, in which eolian sediments may be partly to totally lithified by micrite or spar cement, grades upward into a zone of moderate alteration, where many grains have a micrite coating, and random needle fibers of calcite and calcified tubules are common. Caliche pisolites and rhizomorphs are found at the top of the moderate alteration zone, along with stringers of laminated calcrete. The zone of intense alteration at the top of the vertical sequence is characterized by deposition of laminated calcrete, total micritization of the original grainstone, the development of terra rosa sediments, precipitation of ferroan spar, and brecciation. Analysis of whole-rock samples from two Pleistocene(.) eolianite sequences yield vertical profiles of delta /sup 13/C, delta/sup 18/O, percentage of total organic carbon, delta/sup 13/C/sub org/, and trace-element compositions (wt. % of Fe/sub 2/O/sub 3/ and MgO, and ppm Sr) through the zones of progressive alteration. Trends toward enrichment in Fe/sub 2/O/sub 3/, /sup 12/C, and /sup 16/O, and an increase in organic carbon occur gradually through the moderate alteration zone and are extreme in the intense alteration zone. Microsampling of diagenetic features for isotopic analysis (including micrite and spar cement in the zone of minor alteration, random needle-fiber calcite, pisolites, rhizomorphs, calcrete, and ferroan spiar and micrite) provides useful information to determine the processes responsible for developing specific diagenetic fabrics and the timing of these events.
- Research Organization:
- Indiana Univ., Bloomington
- OSTI ID:
- 5300968
- Report Number(s):
- CONF-860624-
- Conference Information:
- Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 70:5
- Country of Publication:
- United States
- Language:
- English
Similar Records
Closed-system vadose diagenesis in the Holocene Cancun Eolianite, Isla Cancun, Yucatan Peninsula, Mexico
Calcrete profiles and porosity development in the Wagon Wheel (Pennsylvanian) field, Ward County, Texas
Petrology of Mississippian carbonate eolianites and associated facies: Ste. Genevieve Limestone of Indiana
Conference
·
Tue May 01 00:00:00 EDT 1990
· AAPG Bulletin (American Association of Petroleum Geologists); (USA)
·
OSTI ID:6699746
Calcrete profiles and porosity development in the Wagon Wheel (Pennsylvanian) field, Ward County, Texas
Conference
·
Tue May 01 00:00:00 EDT 1990
· AAPG Bulletin (American Association of Petroleum Geologists); (USA)
·
OSTI ID:7034376
Petrology of Mississippian carbonate eolianites and associated facies: Ste. Genevieve Limestone of Indiana
Conference
·
Tue May 01 00:00:00 EDT 1990
· AAPG Bulletin (American Association of Petroleum Geologists); (USA)
·
OSTI ID:6713525