What primarily causes the crystallization of minerals in chemical sedimentary rocks?

The crystallization of minerals in chemical sedimentary rocks is primarily caused by the evaporation of water in dry climates. In these environments, as water bodies (like lakes or seas) experience high evaporation rates due to climate conditions, the concentration of dissolved minerals in the remaining water increases. When the water becomes saturated with these minerals, they begin to precipitate out of the solution, leading to the formation of solid mineral crystals. This process can significantly contribute to the development of various types of chemical sedimentary rocks, including limestone and evaporites like halite and gypsum.

The other options involve processes that are not directly related to the formation of chemical sedimentary rocks. Pressure from overlying sediments affects the lithification of sediments into sedimentary rock but is not a driving force for crystallization in this context. Cooling of lava flows pertains to igneous rock formation, where minerals crystallize from molten rock rather than from solutions. Similarly, heat from magma intrusion is associated with metamorphic processes and the crystallization of minerals under high temperature and pressure, rather than the evaporation and precipitation processes that define chemical sedimentary rocks.