Abstract
Dioctahedral smectite is present as a retrograde alteration product of chlorite in Permian-Triassic red slates of the Malaguide Complex in Sierra de Espuña (Betic Cordillera). Mineral assemblages and textures, illite “crystallinity” indices, and fluid inclusion data indicate sub-greenschist facies conditions that reached at least 180°C in the higher-grade tectonic unit of the Malaguide Complex, preceding formation of smectite. Smectite, having K as the dominant interlayer cation, occurs ubiquitously intercalated with trioctahedral chlorite as thin packets of layers and as individual layers that commonly change to chlorite along layers. Although some chlorite is typically homogeneous and trioctahedral, much chlorite shows signs of alteration and has compositions corresponding to different degrees of smectite contaimination. The incompatibility of metamorphic grade with the occurrence of smectite, the general association of chlorite and smectite, and the textural relations collectively show that dioctahedral smectite is derived through replacement of trioctahedral chlorite. Such replacement occurs on a regional basis and demonstrates that caution must be used in interpreting the occurrence of smectite in pelites as being due to prograde processes. Alteration of trioctahedral chlorite under oxidizing conditions due to introduction of phreatic water after uplift of the Betic Cordillera is proposed as the cause of formation of smectite.
Similar content being viewed by others
References
Ahn JH, Peacor DR (1986) Transmission and analytical electron microscopy of the smectite to illite transition. Clays Clay Miner 34:165–179
Ahn JH, Peacor DR (1987) Kaolinitization of biotite: TEM data and implications for an alteration mechanism. Am Mineral 72:353–356
Banfield JF, Eggleton RA (1988) Transmission electron microscope study of biotite weathering. Clays Clay Miner 3647–60
Fransolet AM, Schreyer W (1984) Sudoite, di/trioctahedral chlorite: a stable low-temperature phase in the system MgO−Al2O3−SiO2−H2O. Contrib Mineral Petrol 86:409–417
Freed RL, Peacor DR (1989) Variability in temperature of the smectite/illite reaction in Gulf Coast sediments. Clay Miner 24:171–180
Frey M (1987) Low temperature metamorphism. Blackie, Glasgow
IGME (1974) Mapa geológico de España escala 1:50,000. Hoja 953, Lorca
Jiang WT, Peacor DR, Merriman RJ, Roberts B (1990) Transmission and analytical electron microscopic study of mixed layer illite/smectite formed as an apparent replacement product of diagenetic illite. Clays Clay Miner 38:449–468
Kisch HJ (1987) Correlation between indicators of very low-grade metamorphism. In: Frey M (ed) Low temperature metamorphism, Blackie, London, pp 227–300
Kisch HJ (1991) Illite crystallinity: recommendations on sample preparation, X-ray diffraction settings and interlaboratory samples. J Metamorphic Geol 9:665–670
Kretz R, (1983) Symbols for rock-forming minerals. Am Mineral 68:277–279
Lee JH, Peacor DR, Lewis DD, Wintsch RP (1984) Chlorite-illite/muscovite interlayered and interstratified crystals: a TEM/STEM study. Contrib Mineral Petrol 88:372–385
Li G, Peacor DR, Merriman RJ, Roberts B (in press) The diagenetic to low-grade metamorphic evolution of matrix white micas in the system muscovite-paragonite in a mudrock from Central Wales, UK. Clays Clay Miner
Lorimer GW, Cliff G (1976) Analytical electron microscopy of minerals. In: Wenk HR (ed) Electron microscopy in mineralogy, Springer, Berlin Heidelberg New York, pp 506–519
Makel GH (1981) Differences in tectonic evolution for superposed Malaguide and Alpujarride tectonic units in the Espuña area (Betic Cordilleras Spain). Geol Mijnbouw 60:203–208
Makel GH, Rondeel HE (1979) Differences in stratigraphy and metamorphism between superposed Malaguide and Alpujarride units in the Espuña area (Betic Cordilleras, Spain), Estud Geol 35:109–117
Makumbi MN, Herbillon AJ (1972) Vermiculitisation experimental d'une chlorite. Bull Groupe Fr Argiles XXIV:153–164
Mellini M, Nieto F, Alvarez F, Gómez-Pugnaire MT (1991) Micachlorite intermixing and altered chlorite from the Nevado-Filabride micaschists, Southern Spain. Eur J Mineral 3:27–38
Peacor DR (1992) Diagenesis and low-grade metamorphism of shales and slates. In: Buseck PR (ed) Minerals and reactions at the atomic scale: transmission electron microscopy. Reviews in mineralogy 27. Mineral Soc Am. Washington DC, pp 335–380
Ross GJ (1975) Experimental alteration of chlorites into vermiculites by chemical oxidation. Nature 295:133–134
Ross GJ, Kodama H (1974) Experimental transformation of a chlorite into a vermiculite. Clays Clay Miner 22:205–211
Ross GJ, Kodama H (1976) Experimental alteration of a chlorite into a regularly interstratified chlorite-vermiculite by chemical oxidation. Clays Clay Miner 24:183–190
Shau YH, Peacor DR, Essene EJ (1990) Corrensite and mixed-layer chlorite/corrensite in metabasalt from northern Taiwan: TEM/AEM, EPMA, XRD, and optical study. Contrib Mineral Petrol 105:123–142
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Nieto, F., Velilla, N., Peacor, D.R. et al. Regional retrograde alteration of sub-greenschist facies chlorite to smectite. Contr. Mineral. and Petrol. 115, 243–252 (1994). https://doi.org/10.1007/BF00310765
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00310765