Sepiolite - Palygorskite in Spanish Tertiary Basins: Genetical Patterns in Continental Environments

摘要: Abstract Spanish Tertiary deposits of sepiolite and palygorskite are formed in lacustrine or perimarine environments. According to their geological setting mineralogy they can be grouped into four fundamental types, with the following principal features: 1) Tajo basin type; distal zones alluvial-fans, perennial zones, by precipitation from a Si Mg-rich solution pH between 8 9. Other authigenic minerals this environment were Mg-smectite, palygorskite, carbonates chert. 2) Torrejon tectonic basins on slaty basement partially dissolved chlorite, also direct an alkaline environment. 3) Benfica-San Martin de Pusa appears as clay mineral cement conglomerates sandstones, diagenesis these detrital sediments, slightly rich magnesium. 4) Lebrija palygorskite-sepiolite marls brackish Mg. Palygorskite is thought transformed illite. In all patterns sedimentation occurred under semi-arid seasonably arid climatic conditions during periods calm.