Low-grade evolution of clay minerals and organic matter in fault zones of the Hikurangi prism (New Zealand)
| Autor: | Pierre Malie, Tatiana Maison, Rafael Ferreiro Mählmann, Julien Bailleul, Frank Chanier, Geoffroy Mahieux, Sébastien Potel |
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| Přispěvatelé: | UniLaSalle, Bassins - Réservoirs - Ressources - U2R UPJV-UNIL 7511 (B2R), Université de Picardie Jules Verne (UPJV)-UniLaSalle |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Geochemistry
Metamorphism 020101 civil engineering 02 engineering and technology engineering.material 010502 geochemistry & geophysics 01 natural sciences 0201 civil engineering Diagenesis chemistry.chemical_compound chemistry Geochemistry and Petrology [SDU]Sciences of the Universe [physics] Illite engineering Kaolinite Sedimentary rock Metasomatism Clay minerals Chlorite 0105 earth and related environmental sciences |
| Zdroj: | Clay Minerals Clay Minerals, Mineralogical Society, 2018, 53 (4), pp.579-602. ⟨10.1180/clm.2018.46⟩ |
| ISSN: | 0009-8558 1471-8030 |
| Popis: | Clay minerals and organic matter occur frequently in fault zones. Their structural characteristics and their textural evolution are driven by several formation processes: (1) reaction by metasomatism from circulating fluids; (2) in situ evolution by diagenesis; and (3) neoformation due to deformation catalysis. Clay-mineral chemistry and precipitated solid organic matter may be used as indicators of fluid circulation in fault zones and to determine the maximum temperatures in these zones. In the present study, clay-mineral and organic-matter analyses of two major fault zones – the Adams-Tinui and Whakataki faults, Wairarapa, North Island, New Zealand – were investigated. The two faults analysed correspond to the soles of large imbricated thrust sheets formed during the onset of subduction beneath the North Island of New Zealand. The mineralogy of both fault zones is composed mainly of quartz, feldspars, calcite, chabazite and clay minerals such as illite-muscovite, kaolinite, chlorite and mixed-layer minerals such as chlorite-smectite and illite-smectite. The diagenesis and very-low-grade metamorphism of the sedimentary rock is determined by gradual changes of clay mineral ‘crystallinity’ (illite, chlorite, kaolinite), the use of a chlorite geothermometer and the reflectance of organic matter. It is concluded here that: (1) the established thermal grade is diagenesis; (2) tectonic strains affect the clay mineral ‘crystallinity’ in the fault zone; (3) there is a strong correlation between temperature determined by chlorite geothermometry and organic-matter reflectance; and (4) the duration and depth of burial as well as the pore-fluid chemistry are important factors affecting clay-mineral formation. |
| Databáze: | OpenAIRE |
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