Influence of constituent composition and texture on mineralogy and diagenesis of reef sediments
The close juxtaposition of Holocene and Pleistocene (120,000 y.b.p.) fringing reef deposits along the Jamaican north coast provides an excellent opportunity for the development of models relating original sediment mineralogies and textures to diagenetic alteration of carbonate sediments. Constituent composition controls initial mineralogies of the reef sediments. X-ray diffraction analyses of Holocene reef sediments reveal that aragonite is the most abundant carbonate phase (49-89%), followed by high-Mg calcite (8-46%) and low-Mg calcite (2-12%). Original sediment textural characteristics influence the diagenesis of these deposits. Analyses of Pleistocene back reef and shallow (5-8m) fore reef facies indicate that surface exposures of the back reef facies retain much of their original aragonite and high-Mg calcite, but surface exposures of the fore reef facies have undergone extreme diagenetic alteration to low-Mg calcite. Differential diagenesis of these deposits is attributed to variability initial sorting and permeability of back reef and fore reef sediments. Poorer sorting and reduced permeability of the back reef deposits has restricted fluid flow and concomitant conversion of metastable carbonate phases has been inhibited. Conversely, the better sorting and higher initial permeability of fore reef facies sediments has resulted in increased fluid migration, greater dissolution of aragonite and high-Mg calcite, and reprecipitation of low-Mg calcite in conjunction with the development of a 1m thick caliche cap.
- Research Organization:
- Weber State College, Ogden, UT (USA)
- OSTI ID:
- 6643994
- 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
MINERALOGY
TEXTURE
JAMAICA
DIAGENESIS
REEFS
ARAGONITE
CALCITE
CHEMICAL ANALYSIS
COASTAL REGIONS
GEOLOGIC MODELS
PERMEABILITY
QUATERNARY PERIOD
SEDIMENTS
X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CENOZOIC ERA
COHERENT SCATTERING
DEVELOPING COUNTRIES
DIFFRACTION
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GREATER ANTILLES
ISLANDS
MINERALS
OXYGEN COMPOUNDS
ROCKS
SCATTERING
SEDIMENTARY ROCKS
WEST INDIES
580300* - Mineralogy
Petrology
& Rock Mechanics- (-1989)