Maragos, J. E., 1993. Impact of coastal construction on coral reefs in
the U.S.-affiliated Pacific Islands. Coastal Management, 21,
235–269.
Maragos, J. E., Evans, C., and Holthus, P., 1985. Reef corals in
Kaneohe Bay six years before and after termination of sewage
discharges. In Proceedings of the 5th International Coral Reef
Congress, Tahiti, Vol. 5, pp. 577–582.
Maragos, J. E., Roach, J., Bowers, R. L., Hemmes, D. E.,
Self, R. F. L., Mcneil, J. D., Ells, K., Omeara, P., Vansant, J.,
Sato, A., Jones, J. P., and Kam, D. T. O. Environmental Surveys
Before, During and After Sand Mining Operations at Keauhou
Bay, Hawaii. University of Hawaii, Sea Grant College Program,
Working Paper 28, Honolulu, 65 pp.
Salvat, B. (ed.), 1987. Human Impacts on Coral Reefs: Facts and
Recommendations. Papetoai, Moorea, French Polynesia:
Antenne de Tahiti Museum E.P.H.E.
Woodbury, D. O., 1946. Builders for Battle – How the Pacific Naval
Air Bases Were Constructed. New York: E.P Dutton and Co.
Cross-references
Atolls
Conservation and Marine Protection Areas
Infrastructure and Reef Islands
Lagoon Circulation
Midway Atoll (Hawaiian Archipelago)
Nutrient Pollution/Eutrophication
Pacific Coral Reefs: An Introduction
Sediments, Properties
Wave Set-Up
Waves and Wave-Driven Currents
EOLIANITE
Sue J. McLaren
University of Leicester, Leicester, UK
Synonyms
Aeolianite (United Kingdom); Dunerock (South Africa);
Grès dunaire (Mediterranean); Miliolite (India, Middle
East); Kurkar (Israel)
Definition
Eolianites are cemented sand dunes created by the processes of entrainment, transportation, and deposition on
land, by wind. The accumulated dune sands are subsequently altered by various geochemical processes in
a meteoric (freshwater) environment. Most eolianites have
a high carbonate content, with clasts made up of whole/
fragments of marine skeletons, ooliths, and peloids. Carbonate eolianites are commonly found in sub-tropical to
tropical coastal locations. Silica- or lithic-dominated
eolianites tend to be found in drylands or in more temperate environments. Most recognized eolianites in the landscape are Quaternary in age. Few examples of preQuaternary eolianites exist and this is thought to be due
to misinterpretation of these deposits rather than to their
absence from the stratigraphic record.
The grains making up siliciclastic eolianites are normally coarse silt to sand-sized, well-sorted, and rounded.
In comparison, carbonate dunes contain a wider range of
clast-size and -shape because the carbonate grains have
a lower specific gravity (Frébourg et al., 2008) and some
skeletal fragments are platy in nature, which enable
larger clasts to be wind-entrained. Bedding structures
include cross-bedding and laminations, which represent
the progradation and extension of the dunes. Dune
slipfaces are identifiable as steeply dipping laminae up
to 30–34
. In terms of thickness, eolianites vary from
<1 m to >100 m.
The mineralogical changes associated with the diagenesis of eolianites include the alteration of unstable highMg calcite and aragonite and precipitation of relatively
stable low-Mg calcite. Dissolution of aragonitic shells
and ooids often results in molds with fossil outlines preserved by micritic envelopes. Both air and water fill pore
spaces in the vadose zone giving unevenly distributed
cement patterns. Meniscus, rim, and pore-filling cements
occur with crystal size normally ranging between 5 and
50 mm in diameter and crystal shape typically being bladed,
equant, or syntaxial. Cement sources include dissolution of
bioclasts, ooids, peloids, and carbonate-rich lithoclasts, terrigenous dust, seaspray, leaching of overlying sands, and
precipitation from groundwater or overland flow (McLaren,
2007). Karstification or palaeosols may develop at/above
major unconformities in eolianites and in semi-arid environments calcretes can develop because of processes of carbonate dissolution and rapid reprecipitation.
Relative dating techniques attempted to establish the
age of dunes/eolianites include lithostratigraphy, human
artefacts, and amino acid racemization. Of the numerical
techniques, uranium-series dating on shells is problematic
as they often behave as geochemically open systems.
Radiocarbon dating requires organic matter to be present
in the dunes and only dates back to ~50 ka. Luminescence
dating of terrigenous grains has successfully obtained
ages ranging from a few decades to several hundred thousand years.
Bibliography
Frébourg, G., Hasler, C., Le Guern, P., and Davaud, E., 2008. Facies
characteristics and diversity in carbonate eolianites. Facies, 54,
175–191.
McLaren, S. J., 2007. Aeolianites. In: Nash, D. J., and McLaren, S. J.
(eds.), Geochemical Sediments and Landscapes. Oxford: Blackwell Publishing, pp. 144–172.
Cross-references
Aragonite
Calcite
Calcrete/Caliche
Diagenesis
Electron Spin Resonance Dating (ESR)
Micrite
Ooids
Palaeosols
404
EOLIANITE
the U.S.-affiliated Pacific Islands. Coastal Management, 21,
235–269.
Maragos, J. E., Evans, C., and Holthus, P., 1985. Reef corals in
Kaneohe Bay six years before and after termination of sewage
discharges. In Proceedings of the 5th International Coral Reef
Congress, Tahiti, Vol. 5, pp. 577–582.
Maragos, J. E., Roach, J., Bowers, R. L., Hemmes, D. E.,
Self, R. F. L., Mcneil, J. D., Ells, K., Omeara, P., Vansant, J.,
Sato, A., Jones, J. P., and Kam, D. T. O. Environmental Surveys
Before, During and After Sand Mining Operations at Keauhou
Bay, Hawaii. University of Hawaii, Sea Grant College Program,
Working Paper 28, Honolulu, 65 pp.
Salvat, B. (ed.), 1987. Human Impacts on Coral Reefs: Facts and
Recommendations. Papetoai, Moorea, French Polynesia:
Antenne de Tahiti Museum E.P.H.E.
Woodbury, D. O., 1946. Builders for Battle – How the Pacific Naval
Air Bases Were Constructed. New York: E.P Dutton and Co.
Cross-references
Atolls
Conservation and Marine Protection Areas
Infrastructure and Reef Islands
Lagoon Circulation
Midway Atoll (Hawaiian Archipelago)
Nutrient Pollution/Eutrophication
Pacific Coral Reefs: An Introduction
Sediments, Properties
Wave Set-Up
Waves and Wave-Driven Currents
EOLIANITE
Sue J. McLaren
University of Leicester, Leicester, UK
Synonyms
Aeolianite (United Kingdom); Dunerock (South Africa);
Grès dunaire (Mediterranean); Miliolite (India, Middle
East); Kurkar (Israel)
Definition
Eolianites are cemented sand dunes created by the processes of entrainment, transportation, and deposition on
land, by wind. The accumulated dune sands are subsequently altered by various geochemical processes in
a meteoric (freshwater) environment. Most eolianites have
a high carbonate content, with clasts made up of whole/
fragments of marine skeletons, ooliths, and peloids. Carbonate eolianites are commonly found in sub-tropical to
tropical coastal locations. Silica- or lithic-dominated
eolianites tend to be found in drylands or in more temperate environments. Most recognized eolianites in the landscape are Quaternary in age. Few examples of preQuaternary eolianites exist and this is thought to be due
to misinterpretation of these deposits rather than to their
absence from the stratigraphic record.
The grains making up siliciclastic eolianites are normally coarse silt to sand-sized, well-sorted, and rounded.
In comparison, carbonate dunes contain a wider range of
clast-size and -shape because the carbonate grains have
a lower specific gravity (Frébourg et al., 2008) and some
skeletal fragments are platy in nature, which enable
larger clasts to be wind-entrained. Bedding structures
include cross-bedding and laminations, which represent
the progradation and extension of the dunes. Dune
slipfaces are identifiable as steeply dipping laminae up
to 30–34
. In terms of thickness, eolianites vary from
<1 m to >100 m.
The mineralogical changes associated with the diagenesis of eolianites include the alteration of unstable highMg calcite and aragonite and precipitation of relatively
stable low-Mg calcite. Dissolution of aragonitic shells
and ooids often results in molds with fossil outlines preserved by micritic envelopes. Both air and water fill pore
spaces in the vadose zone giving unevenly distributed
cement patterns. Meniscus, rim, and pore-filling cements
occur with crystal size normally ranging between 5 and
50 mm in diameter and crystal shape typically being bladed,
equant, or syntaxial. Cement sources include dissolution of
bioclasts, ooids, peloids, and carbonate-rich lithoclasts, terrigenous dust, seaspray, leaching of overlying sands, and
precipitation from groundwater or overland flow (McLaren,
2007). Karstification or palaeosols may develop at/above
major unconformities in eolianites and in semi-arid environments calcretes can develop because of processes of carbonate dissolution and rapid reprecipitation.
Relative dating techniques attempted to establish the
age of dunes/eolianites include lithostratigraphy, human
artefacts, and amino acid racemization. Of the numerical
techniques, uranium-series dating on shells is problematic
as they often behave as geochemically open systems.
Radiocarbon dating requires organic matter to be present
in the dunes and only dates back to ~50 ka. Luminescence
dating of terrigenous grains has successfully obtained
ages ranging from a few decades to several hundred thousand years.
Bibliography
Frébourg, G., Hasler, C., Le Guern, P., and Davaud, E., 2008. Facies
characteristics and diversity in carbonate eolianites. Facies, 54,
175–191.
McLaren, S. J., 2007. Aeolianites. In: Nash, D. J., and McLaren, S. J.
(eds.), Geochemical Sediments and Landscapes. Oxford: Blackwell Publishing, pp. 144–172.
Cross-references
Aragonite
Calcite
Calcrete/Caliche
Diagenesis
Electron Spin Resonance Dating (ESR)
Micrite
Ooids
Palaeosols
404
EOLIANITE