A statistics-based method for the short-wave infrared spectral analysis of altered rocks: An example from the Acoculco Caldera, Eastern Trans-Mexican Volcanic Belt
Por:
Canet C., Arana L., González-Partida E., Pi T., Prol-Ledesma R.M., Franco S.I., Villanueva-Estrada R.E., Camprubí A., Ramírez-Silva G., López-Hernández A.
Publicada:
1 abr 2010
Resumen:
We propose a simple graphic and statistical method for processing short-wave infrared (SWIR) reflectivity spectra of alteration minerals, which classifies spectra according to their shape and absorption features, thus obtaining groups of spectra equivalent to mineral assemblages. It also permits selection of fewer samples for further mineralogical verification. This method uses the SWIR spectra without hull subtraction. The first step is to normalize the spectra reflectivity to 100% at maximum. In order to reduce the reflectance dataset, a decimation filter is used, obtaining one value for each 10 nm. Subsequently, a cluster analysis using as input data the decimated reflectance values for each sample results in a dendrogram that deduces assemblages of SWIR active minerals. The effectiveness of this methodology is illustrated with a study of the Acoculco Caldera, which is a geothermal prospective area. Two major alteration zones have been recognized: a shallow one with ammonium illite,
Filiaciones:
Canet C.:
Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico
Arana L.:
Posgrado en Ciencias de la Tierra, Universidad Nacional Autónoma de México, Ciudad Universitaria Delegación Coyoacán, 04510 México D.F., Mexico
González-Partida E.:
Univ Nacl Autonoma Mexico, Ctr Geociencias, Santiago De Queretaro 76230, Qro, Mexico
Pi T.:
Univ Nacl Autonoma Mexico, Inst Geol, Mexico City 04510, DF, Mexico
Prol-Ledesma R.M.:
Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico
Franco S.I.:
Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico
Villanueva-Estrada R.E.:
Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico
Camprubí A.:
Univ Nacl Autonoma Mexico, Inst Geol, Mexico City 04510, DF, Mexico
Ramírez-Silva G.:
Gerencia de Proyectos Geotermoeléctricos, Comisión Federal de Electricidad, Alejandro Volta 655, 58290 Morelia, Michoacán, Mexico
López-Hernández A.:
Gerencia de Proyectos Geotermoeléctricos, Comisión Federal de Electricidad, Alejandro Volta 655, 58290 Morelia, Michoacán, Mexico
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