Which dolomitization model involves dolomitizing fluids being seawater?

Which dolomitization model involves dolomitizing fluids being seawater?

• A. Seawater
• B. Evaporative
• C. Seepage Reflux
• D. Mixing-Zone

Answer: (A)

Dolomitization driven by seawater emphasizes that the dolomitizing fluid is seawater itself. In this model, seawater circulates through porous or fractured carbonate rocks, delivering its magnesium-rich solution. The Mg2+ exchanges with Ca2+ in the calcite lattice, transforming the rock into dolomite (CaMg(CO3)2). The setting is typically nearshore or sabkha-like environments where seawater can move through sediments, so the primary agent causing the replacement is marine water rather than a brine formed by evaporation or fluids coming from below. Other models involve fluids that are not simply seawater flow, such as evaporatively concentrated brines, upward-seeping fluids from underlying units, or mixing between seawater and freshwater in a boundary zone. While those fluids can be seawater-derived in origin, the defining aspect of the seawater model is that pure seawater itself is the dolomitizing fluid.

Dolomitization driven by seawater emphasizes that the dolomitizing fluid is seawater itself. In this model, seawater circulates through porous or fractured carbonate rocks, delivering its magnesium-rich solution. The Mg2+ exchanges with Ca2+ in the calcite lattice, transforming the rock into dolomite (CaMg(CO3)2). The setting is typically nearshore or sabkha-like environments where seawater can move through sediments, so the primary agent causing the replacement is marine water rather than a brine formed by evaporation or fluids coming from below.

Other models involve fluids that are not simply seawater flow, such as evaporatively concentrated brines, upward-seeping fluids from underlying units, or mixing between seawater and freshwater in a boundary zone. While those fluids can be seawater-derived in origin, the defining aspect of the seawater model is that pure seawater itself is the dolomitizing fluid.