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3 SURVEY RESULTS 
3.1 Lithology and Structural Geology 
There were six major lithologic units interpreted from the Landsat TM and radar imageries (from oldest to youngest): 
(1) Cretaceous ultramafics; (2) Tertiary sediments (limestone); (3) Tertiary clastics; (4) Tertiary volcanics 
(Catmon/Mahayag volcanics); (5) Quaternary volcanics (Tamar/Cantodoc/ Cabalian) and (6) Quaternary alluvium 
(Figure 2). The chronological ordering and lithologic discrimination is based on the apparent spectral signature, tone, 
texture and pattern exhibited by each unit. These morphological features have been extracted from both the Landsat TM 
and Radar imageries. However, the information from these imageries can only establish relative ages and not absolute 
ages of each lithologic unit. This study's stratigraphic interpretation closely resembles the lithologic correlation done by 
Leynes et al. (1996). However, new thermoluminescence dating by Ramos et al. (1998) had constrained the absolute 
ages of Tamar (490-670 ka.), Cantodoc (510 ka.) and Cabalian (17 ka.) volcanic units to Pleistocene age. This result 
was adopted in the chronology of the different geologic units (Figure 2). 
  
  
  
    
  
    
  
Tamar 
Mt. Cantodoc 
       
  
  
  
SAR 
, Cretaceo 
Tertiary Ultramafics 
Clastics 
DEM 
Figure 3b. Hill-shaded DEM of SLGP. 
  
Figure 3a. Composite lineament map at SLGP. 
  
  
  
  
  
Structural lineaments that were drawn using the Landsat TM and Radar imageries (Figure 3a) were based on stream 
offsets, linear valleys/ridges, ridge offsets, stratigraphic contacts and crosscutting faults. A three-dimensional view of 
SLGP with NW hill-shading is shown in Figure 3b. Three structural blocks (Figure 3c) were discerned from the 
imagery: (1) Cretaceous ultramafics/Tertiary clastics fault block (Western block); (2) Tertiary to Quaternary volcanics 
fault block (NE block); and (3) Quaternary Cabalian/Cantodoc fault block (SE block). The western block is dominated 
by WNW structural lineaments while the NE block contains mostly NE-striking lineaments. However, the SE block 
covering Mts. Cabalian and Cantodoc are dominated by NW-trending fault sets. The occurrence of WNW to NW fault 
sets could have been strongly influenced by the active, generally sinistral Philippine Fault and splays (along the 
Hindagan-Panian and Catmon-Bisay vicinities). The fault set analyses conducted by Leynes et al. (1996) is interpreted 
in this study to favor localized ENE-trending compressional regime on observed NW fault sets. This, therefore, implies 
that NE to ENE-trending fault sets at the NE and SE structural block (Tertiary/Quaternary volcanics and sediments) 
have extensional properties which are potential channels for hydrothermal fluids. 
  
  
     
   
  
     
  
         
    
a wc 1 
PET RES TEL 
  
wp Sem siemens 
  
  
  
Figure 3c. Structural blocks at SLGP based on Landsat 
TM. 
  
  
  
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 223