Por favor, use este identificador para citar o enlazar a este item:
http://hdl.handle.net/10261/32395
COMPARTIR / EXPORTAR:
SHARE CORE BASE | |
Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL | DATACITE | |
Título: | Microstructures of intergrown phyllosilicate grains from Verrucano metasediments (northern Apennines, Italy) |
Autor: | Giorgetti, G.; Memmi, Isabella; Nieto, F. | Palabras clave: | Phyllosilicate Verrucano Italy SEM TEM |
Fecha de publicación: | 1997 | Editor: | Springer Nature | Citación: | Contributions to Mineralogy and Petrology 128(2-3): 127-138 (1997) | Resumen: | Interleaved phyllosilicate grains (IPG) of various compositions are widespread in low-grade Verrucano metasediments of the northern Apennines (Italy). They are ellipsoidal or barrel shaped, up to 300–400 μm long and they are often kinked and folded; phyllosilicate packets occur as continuous lamellae or as wedge-shaped layers terminating inside the grain. Using electron microscopy techniques (SEM, TEM) six types of IPG have been distinguished on the basis of their mineralogical composition: (1) Chl+Ms ± Kln; (2) Chl+ Ms+Pg ± Kln; (3) Ms+Prl ± Pg; (4) Ms+Prl+Su; (5) Ms+Prl+Chl+Su; (6) Su+Ms. Types (1) and (2) are mainly composed of chlorite, with Ms and Pg as minor phases; Kln grows on Ms in highly weathered samples. Types (3), (4), (5), and (6) are composed of muscovite, with intergrown Prl, Chl, Su and new-formed muscovite. The IPG show all kinds of contacts: from coherent grain boundaries with parallel basal planes and along-layer transitions to low- and high-angle grain boundaries. The IPG formed on pristine minerals such as chlorite and muscovite. The transformations took place during the prograde and retrograde metamorphic path of the rocks: they were facilitated by deformation and they occurred in equilibrium with a fluid phase, which allowed cation diffusion. Prograde reactions [Chl = Ms (or Pg); Ms = Prl; Ms = Chl] involve dehydration and sometimes a decrease in volume, whereas retrograde reactions (Ms = Kln; Ms = Su) involve hydration and an increase in volume. These transformations do not simply occur through an interchange of cations, but often involve deep structural changes: transitions from one phyllosilicate to another generally proceed through dissolution-recrystallization reactions. In conclusion, Verrucano IPG represent microstructural sites which have not completely equilibrated with the whole rock and whose mineral assemblage depends on the original composition of the microstructural sites. | Descripción: | 12 páginas, 11 figuras, 3 tablas | Versión del editor: | http://dx.doi.org/10.1007/s004100050299 | URI: | http://hdl.handle.net/10261/32395 | DOI: | 10.1007/s004100050299 | ISSN: | 0010-7999 | E-ISSN: | 1432-0967 |
Aparece en las colecciones: | (IACT) Artículos |
Ficheros en este ítem:
Fichero | Descripción | Tamaño | Formato | |
---|---|---|---|---|
Giorgetti et al(1997).doc | 1,64 MB | Microsoft Word | Visualizar/Abrir |
CORE Recommender
SCOPUSTM
Citations
25
checked on 22-mar-2024
WEB OF SCIENCETM
Citations
26
checked on 25-feb-2024
Page view(s)
345
checked on 28-mar-2024
Download(s)
177
checked on 28-mar-2024
Google ScholarTM
Check
Altmetric
Altmetric
NOTA: Los ítems de Digital.CSIC están protegidos por copyright, con todos los derechos reservados, a menos que se indique lo contrario.