La versión final de este artículo es de uso interno de la institución.
Consulte el artículo en la página del editor
Consulte la política de Acceso Abierto del editor


Mica-chlorite mixed-layering was identified by X-ray diffraction (XRD) as a major or subordinate constituent in several slates of the Puncoviscana Formation from Sierra de Mojotoro (Eastern Cordillera, NW Argentina). In order to determine the crystallochemical characteristics of these mixed-layered sequences and interpret their petrological meaning, anchizonal slate P90 was chosen for TEM observations. In this slate, dioctahedral mica and chlorite form interleaved phyllosilicate grains (IPG) or stacks, up to 110 μm long, preferentially oriented with (001) planes at a high angle to the slaty cleavage but also oblique to S0. In agreement with XRD results, the main phyllosilicates identified by transmission electron microscopy (TEM) were dioctahedral mica and random mixed-layer muscovite-chlorite, with chlorite in subordinate amounts and scarce smectite. In the lattice-fringe images of mixed-layer packets, a sequence of irregular stacking that produced apparent 24 Å (10 + 14) layers was observed, but it was frequently possible to distinguish the 10 Å layers from adjacent 14 Å layers. In nearly all packets, 14 Å layers prevail, exhibiting 14 Å:10 Å ratios between 1:1 and 3:1. Some elongated lenticular fissures which are probably a consequence of layer collapse caused by the TEM vacuum were identified in these packets. The straight, continuous appearance of lattice fringes plus the scarce evidence of collapsed layers identified suggest that these packets correspond principally to mixed-layer muscovite-chlorite, which is confirmed by analytical electron microscopy analyses. However, smectite-like layers are probably the third component of some of these mixed-layer sequences, which may account for their high Si and low (Fe + Mg) contents, their low interlayer charge in relation to theoretical interlayer muscovite-chlorite, and for the presence of Ca in the interlayer site. Textural relationships between chlorite and muscovite packets in IPG along with the observed transformations from 14 Å to 10 Å along the layer, is compatible with a prograde metamorphic replacement of chlorite in stacks by dioctahedral mica layers, probably in the presence of an aqueous fluid. © 2005 The Mineralogical Society.


Documento: Artículo
Título:Origin of mixed-layered (R1) muscovite-chlorite in an anchizonal slate from Puncoviscana Formation (Salta Province, Argentina)
Autor:Do Campo, M.; Nieto, F.
Filiación:Instituto de Geocronología y Geología Isotópica, Facultad de Ciencias Exactas y Naturales, U.B.A., 1428 Buenos Aires, Argentina
Departamento de Mineralogía y Petrología, I.A.C.T., Universidad de Granada-CSIC, Avda. Fuentenueva s/n, 18002 Granada, Spain
Palabras clave:Anchizone; Argentina; Central Andes; Mixed-layering; Puncoviscana Formation; Crystal lattices; Crystallography; Energy dispersive spectroscopy; Image analysis; Metamorphic rocks; Mica; Scanning electron microscopy; Slate; Transmission electron microscopy; X ray diffraction analysis; Anchizonal slate; Argentina; Lattice fringes; Mixed layering; Muscovite-chlorite; Chloride minerals; chlorite; clay mineral; mica; mineral alteration; Argentina; Salta [Argentina]; South America; Western Hemisphere; World
Página de inicio:317
Página de fin:332
Título revista:Clay Minerals
Título revista abreviado:Clay Miner.


  • Ahn, J.H., Peacor, D.R., Transmission and analytical electron microscopy of the smectite- to illite transition (1986) Clays and Clay Minerals, 34, pp. 165-179
  • Bailey, S.W., Nomenclature for regular interstratifications (1982) American Mineralogist, 67, pp. 394-398
  • Champness, P.E., Cliff, G., Lorimer, G.W., Quantitative analytical electron microscopy (1981) Bulletin De Mineralogie, 104, pp. 236-240
  • Cliff, G., Lorimer, G.W., The quantitative analysis of thin specimens (1975) Journal of Microscopy, 103, pp. 203-207
  • Do Campo, M., Metamorfismo del basamento en la Cordillera Oriental y borde oriental de la Puna (1999) Geología Del Noroeste De Argentina, pp. 41-51. , (G. González Bonorino, R. Omarini and J. Viramonte, editors). XIV Congreso Geológico Argentino, Salta, Tomo I, Argentina
  • Do Campo, M., (1999) Mineralogía, Geoquímica Y Geocronología De La Formación Puncoviscana (Neoproterozoico) Entre Los 23°30′ Y 25°50′ De Latitud Sur, Noroeste De Argentina, p. 287. , PhD thesis (unpublished), Universidad de Buenos Aires, Argentina
  • Do Campo, M., Nieto, F., Transmission electron microscopy study of the very low-grade metamorphic evolution in Neoproterozoic pelites of the Puncoviscana Formation (Cordillera Oriental, NW Argentina) (2003) Clay Minerals, 38, pp. 459-481
  • Do Campo, M., Nieto, F., Omarini, R., Mineralogía de arcillas y metamorfismo de la Formación Puncoviscana en localidades de la Cordillera Oriental y Puna, Argentina (1998) Actas 10° Congreso Latinoamericano De Geología, Buenos Aires, Argentina, 2, pp. 217-223
  • Dong, H., Peacor, D.R., TEM observations of coherent stacking relations in smectite, I/S and illite of shales: Evidence for MacEwan crystallites and dominance of 2M1, polytypism (1996) Clays and Clay Minerals, 44, pp. 257-275
  • Eggleton, R.A., Banfield, J.F., The alteration of granitic biotite to chlorite (1985) American Mineralogist, 70, pp. 902-910
  • Essene, E.J., Peacor, D.R., Clay mineral thermometry: A critical perspective (1995) Clays and Clay Minerals, 43, pp. 540-553
  • Franceschelli, M., Leoni, L., Sartori, F., Crystallinity distribution and crystallinity-b0 relationships in white K-micas of Verrucano metasediments (Northern Apennines, Italy) (1991) Schweizerische Mineralogische Und Petrographische Mitteilungen, 71, pp. 161-167
  • Giorgetti, G., Memmi, I., Nieto, F., Microstuctures of intergrown phyllosilicate grains from Verrucano metasediments (northern Apennines, Italy) (1997) Contributions to Mineralogy and Petrology, 128, pp. 127-138
  • Greg, W.J., Deformation of chlorite-mica aggregates in cleaved psammitic and pelitic rocks from Islesboro, Maine, USA (1986) Journal of Structural Geology, 8, pp. 59-68
  • Guidotti, C.V., Sassi, F.P., Blencoe, J.G., Compositional controls on the a and b cell dimensions of 2M1 muscovite (1989) European Journal of Mineralogy, 1, pp. 71-84
  • Jezek, P., Análisis sedimentológico de la Formación Puncoviscana entre Tucumán y Salta (1990) El Ciclo Pampeano En El Noroeste Argentino, pp. 9-36. , (F.G. Aceñolaza, H. Miller & A.J. Toselli, editors). Serie Correlación Geológica N° 4, Universidad Nacional de Tucumán, Argentina
  • Kisch, H.J., Illite crystallinity: Recommendations on sample preparation, X-ray diffraction settings, and interlaboratory samples (1991) Journal of Metamorphic Geology, 9, pp. 665-670
  • Knipe, R.J., The interaction of deformation and metamorphism in slates (1981) Tectonophysics, 78, pp. 249-272
  • Lee, J.H., Peacor, D.R., Ordered 1:1 interstratifications of illite and chlorite. A transmission and analytical electron microscopy study (1985) Clays and Clay Minerals, 33, pp. 463-467
  • Lee, J.H., Peacor, D.R., Lewis, D.D., Wintsch, R.P., Chlorite-illite/muscovite interlayered and interstratified crystals: A TEM/STEM study (1984) Contributions to Mineralogy and Petrology, 88, pp. 372-385
  • Li, G., Peacor, D.R., Merriman, R.J., Roberts, B., van der Pluijm, B.A., TEM and AEM constraints on the origin and significance of chlorite-mica stacks in slates: An example from Central Wales, U.K (1994) Journal of Structural Geology, 16, pp. 1139-1157
  • Mon, R., Hong, F.D., The structure of the Precambrian and Lower Paleozoic basement of the Central Andes between 22° and 32°S. Lat (1991) Geologische Rundschau, 80, pp. 745-758
  • Mon, R., Hong, F.D., Estructura del basamento proterozoico y paleozoico inferior del norte argentino (1996) Revista De La Asociación Geológica Argentina, 51, pp. 3-14
  • Nieto, F., Chemical composition of metapelitic chlorites: X-ray diffraction and optical property approach (1997) European Journal of Mineralogy, 9, pp. 829-841
  • Nieto, F., Velilla, N., Peacor, D.R., Ortega Huertas, M., Regional retrograde alteration of sub-greenschist facies chlorite to smectite (1994) Contributions to Mineralogy and Petrology, 115, pp. 243-252
  • Nieto, F., Ortega-Huertas, M., Peacor, D.R., Arostegui, J., Evolution of illite/smectite from early diagenesis through incipient metamorphism in sediments of the Basque-Cantabrian Basin (1996) Clays and Clay Minerals, 44, pp. 304-323
  • Nieto, F., Mata, M.P., Bauluz, B., Giorgetti, G., Árkai, P., Peacor, D.R., Retrograde diagenesis, a widespread process on a regional scale (2005) Clay Minerals, 40, pp. 93-104
  • Omarini, R.H., (1983) Caracterización Litológica, Diferenciación Y Génesis De La Formación Puncoviscana Entre El Valle De Lerma Y La Faja Eruptiva De La Puna, p. 202. , PhD thesis (unpublished), Universidad Nacional de Salta, Argentina
  • Omarini, R., Baldis, B.A.J., Sedimentología y mecanismos deposicionales de la Formación Puncoviscana (Grupo Lerma, Precámbrico-Cámbrico) del noroeste Argentino (1984) 9th Congreso Geológico Argentino, pp. 384-398. , Bariloche, Argentina
  • Ruíz Cruz, M.D., Mixed-layer mica-chlorite in very low-grade metaclastites from the Maláguide Complex (Betic Cordilleras, Spain) (2001) Clay Minerals, 36, pp. 307-324
  • Shau, Y.H., Peacor, D.R., Essene, E.J., Corrensite and mixed-layer chlorite/corrensite in metabasalt from northern Taiwan: TEM/AEM, EMPA, XRD, and optical studies (1990) Contributions to Mineralogy and Petrology, 105, pp. 123-142
  • Turner, J.C.M., Estratigrafía de la Sierra de Santa Victoria y adyacencias (1960) Academia Nacional De Ciencias Boletín, 41, pp. 163-196. , Córdoba
  • Van der Pluijim, B.A., Lee, J.H., Peacor, D.R., Analytical electron microscopy and the problem of potassium diffusion (1988) Clays and Clay Minerals, 36, pp. 498-504
  • Veblen, D.R., Ferry, J.M., A TEM study of the biotite-chlorite reaction and comparison with petrologic observations (1983) American Mineralogist, 68, pp. 1160-1168
  • Warr, L.N., Rice, A.H.N., Interlaboratory standardization and calibration of clay mineral crystallinity and crystallite size data (1994) Journal of Metamorphic Geology, 12, pp. 141-152
  • Weber, K., Kinematic and metamorphic aspects of cleavage formation in very low grade metamorphic slates (1981) Tectonophysics, 78, pp. 297-306


---------- APA ----------
Do Campo, M. & Nieto, F. (2005) . Origin of mixed-layered (R1) muscovite-chlorite in an anchizonal slate from Puncoviscana Formation (Salta Province, Argentina). Clay Minerals, 40(3), 317-332.
---------- CHICAGO ----------
Do Campo, M., Nieto, F. "Origin of mixed-layered (R1) muscovite-chlorite in an anchizonal slate from Puncoviscana Formation (Salta Province, Argentina)" . Clay Minerals 40, no. 3 (2005) : 317-332.
---------- MLA ----------
Do Campo, M., Nieto, F. "Origin of mixed-layered (R1) muscovite-chlorite in an anchizonal slate from Puncoviscana Formation (Salta Province, Argentina)" . Clay Minerals, vol. 40, no. 3, 2005, pp. 317-332.
---------- VANCOUVER ----------
Do Campo, M., Nieto, F. Origin of mixed-layered (R1) muscovite-chlorite in an anchizonal slate from Puncoviscana Formation (Salta Province, Argentina). Clay Miner. 2005;40(3):317-332.