Mineralogy and geochemistry of Devonian detrital rocks from the Iberian Range (Spain)
| Autor: | J. M. González López, C. Fernández-Nieto, B. Bauluz Lazaro, M. J. Mayayo Burillo |
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| Rok vydání: | 1995 |
| Předmět: |
Felsic
Maturity (sedimentology) Geochemistry Mineralogy 020101 civil engineering 02 engineering and technology engineering.material 010502 geochemistry & geophysics 01 natural sciences Devonian 0201 civil engineering Diagenesis Geochemistry and Petrology Clastic rock Illite engineering Sedimentary rock Clay minerals Geology 0105 earth and related environmental sciences |
| Zdroj: | Clay Minerals. 30:381-394 |
| ISSN: | 1471-8030 0009-8558 |
| DOI: | 10.1180/claymin.1995.030.4.10 |
| Popis: | Two profiles in Devonian marine deposits have been studied, consisting of pelites, subgreywackes, greywackes and quartzites. Quartz and clay minerals are major components and feldspar and calcite are minor ones. Phyllosilicates in the fine fractions are kaolinite and illite; kaolinite has a high degree of ordering; illite is predominantly of a 1Md polytype, with low Na content and poor crystallinity and has a phengitic composition in greywackes, whereas in pelites it is muscovitic in composition. Both phyllosilicates may be inherited from a source area with intensive weathering processes, although illite may also be a diagenetic phase. These mineral characteristics indicate that the Devonian rocks did not reach the anchizone boundary in their post-depositional evolution.The chemical composition of pelites and subgreywackes reveals a high degree of chemical maturity. Chondrite-normalized REE patterns indicate a higher degree of weathering of these Devonian sediments than of Post-Archaean Australian Shales (PAAS), possibly as a consequence of sedimentary recycling processes. The REE patterns of the Devonian rocks in addition to the high Th/Sc, La/Sc and Th/Co ratios suggest a felsic composition of the primitive source area, probably a K-rich granite. |
| Databáze: | OpenAIRE |
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