Procesos de alteración supergénica en Sierra Almagrera (Almería): Los sulfatos solubles

Laburpena

Of the different weathering processes developed in Sierra Almagrera, those correspondent to apparition of the hydrated solute Sulfates are collected in this paper. The identified phases number is large, close to 30, corresponding the most frecuent to Fe 2+, Fe 3+, Mg 2+ , Al3+, Ca2+ and Na+ sulfates. Quantitative composition of some samples has been obtained from the chemical and mineralogical data. Thes study also reveal the zonal distribution of some sulfates, especially those concerning to Mg2+, Ca2+ and Na+. From the genetic point of view, the Fe 2+ and Fe 3+ sulfates are the most important phases, Since they permit to establish the possible transformation sequences. These sequences are summarized in two reactions: a) Copiapite --> Coquimbite| Fibroferrite | +H2O Butlerite | b) Solution --> |Melanterite-Rozonite- Szomolnokite | |Coquimbite | --> Roemerite (Fibroferrite) On the other hand, the Melanterite-Rozenite relations in Sierra Almagrera can be justified applaing the equilibrium diagram of ERNEST et aL (1965 ). In this zona both minerals can occur simultaneously. Finally, according to the results, we propose a general weathering scheme, in wich secondary transformations have not been taked into account.