Soil and Climate

Many of the caves in the Yucatan peninsula are found in the calcareous sub-soil. This type of soil has a very high pH and is very alkaline as well. This is mainly die to the weak acidity in carbonic acid.  Related with climate, a record of multi-technique fluid inclusion data and pollen spectra from cave and mine gypsum indicates surprisingly that climatic changes occurring at Naica could have controlled fluid composition in these caves, and hence crystal growth. Like much of the Carribean,the peninsula lies within the Atlantic Hurricane Belt, and with it's almost uniformly flat terrain it is vulnerable to these large storms coming from the east. The 2005 Hurricane season was extremely destructive to this region. Hurricane Wilma and Hurricane Emily were class 5 storms that were quite damaging. How this effects the caves is unknown, due to their relative depth from the surface. This region has heavy rainfall mainly form April to October. Breezes have a cooling effect, and humidity is generally  high. "Microthermometry and LA-ICP-Mass Spectrometry of fluid inclusions indicate that the shallow, chemically peculiar, saline fluid (up to 7.7 eq. wt.%NaCl) of CLE could have formed from evaporation, during a dry and hot climatic period. The fluid of the deep caves was instead of low salinity (∼ 3.5 eq. wt.% NaCl) and chemically homogeneous, and was poorly affected by evaporation".(*) It is thought that the that the combining of these two fluids maintained at a stable condition allowed for the massive gypsum crystals to form. This seems to have taken place during cycles of warm-dry and fresh-wet climatic periods, which is typical weather for the region. Pollen grains were taken from a 35 ka-old gypsum crystal and it corresponds to the data that it was these soisl and water that came from a mixed broadleaf wet forest. This suggests precipitation during a fresh-wet climatic period and shows how this process can occur over time.

http://www.sciencedirect.com/science/article/pii/S0012821X09007195 (*)

http://archive.lib.msu.edu/tic/gcman/article/1990jun60.pdf

http://www.geochemicaltransactions.com/content/7/1/6