MAPPING OF HYDROTHERMAL ALTERATION BY REMOTE SENSING AT
THE ACOCULCO CALDERA, PUEBLA, MEXICO
VICENTE TORRES RODRÍGUEZ 1 & GABRIEL ORIGEL GUTIÉRREZ
Unidad de Geotermia, Instituto de Investigaciones Eléctricas, A.P. 1-475, Cuemavaca, Morelos,
62001, México
ABSTRACT
This paper presents a method to recognize
mineralogical features in hydrothermal
alteration zones by means of remote sensing.
The proposed technique is based on the analysis
of the principal components of the included
information for each band of the Landsat
satélite. The technique of the principal
components is an interactive tool, where the
questions are planned in function of field
knowledges of the study zone, such as
mineralogical evidences, experimental
determinations of rocks and minerals, and
radiometric measurements at the surface.
The use of digital image processing for the
reconnaissance and mapping of hydrothermal
alteration zones at the Acoculco Caldera allows
to detect zones with the abundance of iron
oxides and aluminium hydroxides (clays).
1. INTRODUCTION
The geothermal zone of the Acoculco Caldera is
located at the extreme eastern part of the
Transmexican Volcanic Belt (CVT), between
the States of Puebla and Hidalgo, Mexico. This
region is encountered in a straight line 110 km
northeast of Mexico City. (Fig. 1)
The geothermal study of the zone initiated in
1983 as part of a regional inventory of the
principal thermal sites, realized by the Comisión
Federal de Electricidad (QUIJANO 1983). Later,
TELLO (1986) started the investigation of the
thermal waters of the caldera, conforming the
geothermal characteristics of the thermal
Figure 1. Location of study area
manifestations. Parallel to TELLO's study,
CASTILLO and DE LA CRUZ (1986) worked a
primary geological-volcanological map at scale
1:50,000. Their results are interpretated within a
model of the caldera evolution, which were
confirmed by posterior studies (TORRES et al.
1995).
In 1995, the Comisión Federal de Electricidad
(CFE) perforated the exploration well EAC-1
within the caldera to a depth of 2000 m. A
temperature of 274 °C was measured at the
bottom of the well.
1 E-mail: vtorres@iie.org.mx