Geologic and environmental aspects of surface cementation, north coast, Yucatan, Mexico

Journal Article · Fri Sep 01 00:00:00 EDT 1989 · Geology; (USA)

DOI:https://doi.org/10.1130/0091-7613(1989)017<0818:GAEAOS>2.3.CO;2· OSTI ID:6967042

Perry, E; Swift, J; Reeve, A; Sanborn, R; Marin, L ^[1]; Gamboa, J; Villasuso, M ^[2]

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1. Northern Illinois Univ., DeKalb (USA)
2. Universidad de Ycatan (Mexico)

The northernmost part of the fresh-water aquifer of Yucatan, Mexico, is confined near the coast by a thin, flat, nearly impermeable calcareous layer. The authors think it probable that this confining layer is now developing by a process of sedimentation and precipitation of pore-filling cement on and near the surface of older limestone at the landward margin of the swamp that extends virtually continuously along the north Yucatan coast. It is their interpretation that this CaCO{sub 3}-cemented layer, which is 0.5 to 1.4 m thick, developed in the zone of discharge of the fresh-water aquifer. The presence of {sup 14}C (6.0% {plus minus} 0.4% modern carbon in a sample of aquitard) supports the hypothesis that cementation is an ongoing process. Further support comes from the remarkable regularity between modern mean sea level and the elevation of the landward boundary between the confining zone and normal karst along 250 km of coast. Confinement of the aquifer produces an elevation of the piezometric surface to about 0.5 m above mean sea level and a concurrent depression of the fresh-water/salt-water interface to an estimated depth of about 18 m below mean sea level at the coast. Breaching of the confining layer, implicit in some development schemes for the region, could dramatically decrease the thickness of the fresh-water lens, a valuable water resource. The mixing zone beneath the confined part of the aquifer is a chemically active volume that may be vigorously pumped by tides (as evidenced by increased salinity of ground water near the coast), thus making this zone a likely place for rock-water interaction including, perhaps, dolomite formation.

• OSTI ID: 6967042
• Journal Information: Geology; (USA), Vol. 17:9; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
AQUIFERS
BOUNDARY CONDITIONS
MEXICO
CALCIUM CARBONATES
CARBON 14
CEMENTING
COASTAL REGIONS
DOLOMITE
FRESH WATER
GEOLOGIC HISTORY
GEOLOGIC MODELS
HYDROLOGY
LAYERS
LIMESTONE
ORIGIN
PERMEABILITY
PRECIPITATION
ROCK-FLUID INTERACTIONS
SEA LEVEL
SEDIMENTATION
SYNTHESIS
ALKALINE EARTH METAL COMPOUNDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBON ISOTOPES
CARBONATE MINERALS
CARBONATE ROCKS
CARBONATES
DEVELOPING COUNTRIES
EVEN-EVEN NUCLEI
HYDROGEN COMPOUNDS
ISOTOPES
LATIN AMERICA
LEVELS
LIGHT NUCLEI
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERALS
NORTH AMERICA
NUCLEI
OXYGEN COMPOUNDS
RADIOISOTOPES
ROCKS
SEDIMENTARY ROCKS
SEPARATION PROCESSES
WATER
YEARS LIVING RADIOISOTOPES
580000* - Geosciences