About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

Journal of Sedimentary Research (SEPM)


Journal of Sedimentary Petrology
Vol. 54 (1984)No. 4. (December), Pages 1049-1061

Supratidal Evaporitic Dolomite at Ojo De Liebre Lagoon: Mineralogical and Isotopic Arguments for Primary Crystallization

Catherine Pierre (*), Luc Ortlieb (**), Alain Person (*)


This pair deals with a new site of dolomite formation in supratidal evaporite flats, at the southernmost edge of the Ojo de Liebre evaporitic complex (Baja California, Mexico).

The sedimentary context is mostly siliciclastic, except for calcareous outcrops around the flats. Both chemical and isotopic data on the interstitial solutions demonstrate a mixing between Mg2+-rich marine-derived brines and calcium bicarbonate-bearing continental waters, which are subjected to concentration by capillary evaporation. The lack of any in situ solid CaCO3 in the sedimentary matrix argues for direct crystallization of dolomite from aqueous solutions. This is documented by the oxygen isotope compositions of the dolomite which are consistent with deposition under equilibrium conditions of ambient temperature and ^dgr18O of water of the interstitial solutions.

Furthermore, the low ^dgr13C values of the dolomites and the absence of living plants or organisms in the basin indicate that a fraction of the total dissolved inorganic carbon reservoir is biogenic and is mostly provided by continental groundwaters. Therefore, crystallization of dolomite occurs within the sands infiltrated by solutions whose state of saturation relative to dolomite is mainly governed by the chemistry of continental groundwaters mixing with the inflowing marine brines.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Watermarked PDF Document: $14
Open PDF Document: $24