Camit, Rex
-1500
Amagasan ainit-Mahalo
Kaipohan Herr Area
iptong
ugpa Kaipohan llaya-1
[’Kaipohan liaya Altered Grounds (?)
llaya-2
[^t Grounds (?)
n
p
Figure 6.
meter), located WSW of Mt. Cabalian, is consistent with
1999 Conceptual model of SLGP.
and Apuada, 1998) and was associated with the Cabalian system.
In this study, the previously identified Tamar and Canto
Liptong) and thermal springs (e.g. Ilaya-
northeastern sector of SLGP, respectivel
kaipohan, Amagusan kaipohan, Tabunan,
previous geophysical interpretations (Los Bafios, 1998; Catane
doc system supply the kaipohans (i.e. Ilaya, Kapakuhan and
1/2 springs?, Mainit-Mahalo and kapakuhan thermal areas) at the northern and
While the Cabalian system is represented by Hugpa kaipohan, Panangkilon
Nava and Hitunlob thermal areas (Figure 5 and 6). Mainit- Mahalo thermal
area is believed to be the result of the overlapping boundary of Cabalian, Cantodoc and Tamar hydrothermal systems.
S DISCUSSION
The integrated 1999 geoscientific model (Section 4.2) envisaged by this study supports the existence of three
hydrothermal systems (i.e. Cabalian, Cantodoc and Tamar systems). These systems are responsible for the occurrence
of the Ilaya, Mainit-Mahalo and Hugpa geophysical anomalies within SLGP (Figure 5). These potential systems are
believed to be centered beneath the cones of Mts. Cabalian-Cantodoc and Mts. Cantodoc-Tamar, respectively. The
volcanic roots of these Pleistocene volcanic units are probably supplying the heat. Tertiary volcanics, non-clastics (i.e.
limestones) and clastics (i.e. conglomerates, sandstones and siltstones) act as reservoir rocks of the System. Kaipohans
and high-SO, springs generally dominate the upflow portion of the systems (i.e. Cabalian, Cantodoc and Tamar
systems). While high-chloride springs to the west and NE (i.e. Tabunan and Mainit-Mahalo thermal areas, respectively)
outflow to the distal flanks of Mts. Cabalian and Cantodoc.
The one-geothermal system model interpreted from previous geologic, petrologic, geochemical and geophysical data
(Leynes et al., 1996; Bayon, 1996; Rosell and Zaide-Delfin, 1997; Los Baños, 1998; and Catane and Apuada, 1998)
was observed to be located within the conductive zones of Hugpa and Mainit-Mahalo anomalies. These anomalies were
previously interpreted to be related to an upflow zone within vicinities beneath Mts. Cabalian and Cantodoc. However,
the authors observed isolated anomalies (from D.C resistivity and magnetotelluric surveys) ranging from 10-30 ohm-
meters evident to the N and NNE of Mts. Cabalian and Cantodoc (PNOC EDC, 1989; Los Baños, 1998; and Catane and
Apuada, 1998). Previous workers correlate those anomalies (10-30 ohm-meters) to the Hugpa and Mainit-Mahalo
anomalies (evident down to depths of 2000 mBSL) but recent interpretations of Apuada (in prep.) using the same
magnetotelluric data delineated it as a separate anomaly (i.e. Ilaya anomaly). Incidentally, remotely-sensed Landsat TM
and radar imageries show clustering of springs or altered grounds along Ilaya anomaly and in proximity with dominant
NE-trending fault sets within vicinities of the Cantodoc and Tamar volcanics. These evidence discern a probable
existence of a separate geothermal system based mainly on remotely-sensed structural geology and re-assessed
geophysical interpretations.
This study's 1999 geothermal model (Figure 6) is consistent with previous geoscientific studies’ contention of a
combined effect of channeling hydrothermal fluids along permeable lithologic contacts/units (e.g. Tertiary volcanics
and sediments) and faults. These primary and secondary permeability controls, respectively, contribute to the circuitous :
migration of thermal fluids at subsurface levels.
Indirectly, Landsat TM imagery interpretations deduced probable relationship between the occurrence of springs and
altered grounds with said permeability controls. This observation proves that spectral signatures of thermal areas can
226 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.
