A stratigraphic sequence composed bottom to top of limestone, gypsum, and halite indicates which environment?

A stratigraphic sequence composed bottom to top of limestone, gypsum, and halite indicates which environment?

• A. Deep marine
• B. Glacial lake
• C. Coastal swamp
• D. Dry tropical

Answer: (D)

Evaporite minerals form when a body of water becomes isolated and evaporation outpaces input, concentrating dissolved ions until minerals like gypsum and halite precipitate. A bottom-to-top sequence starting with limestone indicates initial marine carbonate deposition, followed by gypsum and then halite as the environment becomes progressively more restricted and arid. This pattern points to an evaporative, arid coastal basin typical of a dry tropical setting, where warm temperatures and high evaporation drive salt build-up. The other environments don’t produce evaporite sequences: deep marine remains carbonate-rich without progressing to gypsum and halite; glacial lakes and coastal swamps lack the sustained evaporation needed to form significant evaporites.

Evaporite minerals form when a body of water becomes isolated and evaporation outpaces input, concentrating dissolved ions until minerals like gypsum and halite precipitate. A bottom-to-top sequence starting with limestone indicates initial marine carbonate deposition, followed by gypsum and then halite as the environment becomes progressively more restricted and arid. This pattern points to an evaporative, arid coastal basin typical of a dry tropical setting, where warm temperatures and high evaporation drive salt build-up. The other environments don’t produce evaporite sequences: deep marine remains carbonate-rich without progressing to gypsum and halite; glacial lakes and coastal swamps lack the sustained evaporation needed to form significant evaporites.