Initial Report on the Geologic Quadrangle Mapping for Palandok Quadrangle

The Mines and Geoscience Bureau Regional Office IX (MGB, R-IX) conducted systematic geological mapping in Palandok Quadrangle (Sheet No. 3544-II) in Zamboanga Peninsula last June 28, 2019 to July 10, 2019 (on going fieldwork) as part of the 2019 Quadrangle Geological Mapping Project. The purpose of the mapping program is to produce 1:50,000 scale geologic quadrangle maps in Region IX, which is one of the least mapped area in the Mindanao. Four quadrangles are targeted for the year 2019 with no published maps, all of which are within Zamboanga Peninsula. It is located in the north central portion of Zamboanga Peninsula. It covers mainly the Municipalities of Salug, Godod, Leon Postigo and a small portion of Sindangan, Zamboanga del Norte. The Geological Quadrangle Mapping Team is composed of Lawrence Zamoras, Ph. D., as the team leader and two other geologists Kris Elvis Alferez and Jordan Gahisan.

Field activities consisted of examination of rock exposures along accessible tracks and in coastal areas, physical and megascopic description of outcrops and rock samples, sampling of representative rock units and favorable units that contain fossils, structural feature measurements of prevalent deformation and sedimentary structures, and photograph documentation. The mapping utilized 1:50,000 topographic base map of NAMRIA furnished through their website. The locations were obtained using the Global Positioning System (Garmin GPSMAP 64s), while the data gathered were plotted on a 1:10,000 topographic map generated from the Interferometric Synthetic Aperture Radar (IFSAR) 2015 of NAMRIA.

This report presents the information gathered during the implementation of the Quadrangle mapping in Central Zamboanga Peninsula and describes the rock units within the study area. It is also intended to supplement the quadrangle map as the final output of the program which is a technical report and GIS-based geologic maps that are expected to be extremely useful for many practical applications such as in mineral exploration, groundwater resource and vulnerability assessment, geohazard mapping, solid waste disposal site selection, land use planning, and other applications.

Palandok Quadrangle (red box), one of the 4 targets for 2019 Quadrangle Geologic Mapping in Region IX, is located within the north-central portion of Zamboanga Peninsula.

Lakewood Quadrangle covers the latitude N 8° 0’ 0” to 8° 10’ 0”, and longitude E 122° 45’ 0” to 123° 0’ 0” is approximately centered in the Municipality of Leon Postigo. From Dipolog Airport, the target municipalities covered by Palandok Quadrangle are easily accessible via all-weathered national road which serves as the main access throughout the entire peninsula. Far-flung areas can be accessed using a motorbike (locally known as habal-habal).

Quarry outcrop of a bedded beige to brown coarse-grained calcarenite with thin layers of pebbly sandstone observed in Barangay Poblacion, Salug, ZdN.
Thinly bedded tuffaceous mudstone-sandstone sequence observed along a road-cut in Barangay Mauswagon, ZdN. It is completely argillized due to series of structural deformities.
Thinly to thickly bedded quartz-rich sandstone and siliceous mudstone sequence with multiple cascading waterfalls observed in Barangay Guisapong, Godod, ZdN.
An outcrop of sheared indurated volcanic breccia along the coast of Barangay Bacong, Salug, ZdN. This unit is capped by the Plio-Pleistocene Liloy Limestone.
Dipping thinly bedded to laminated quartz-rich sandstone sequence observed in Barangay Baluno, Godod, ZdN.
Structurally deformed organic-rich mudstone intruded by a andesitic dike with thin coal seam which is part of the Zamboanga Volcanic Complex observed in Barangay Mauswagon, Godod, ZdN.
Structurally deformed quartz-rich sandstone-mudstone sequence cut by a series of thrust fault which result to a dynamic metamorphic rock (Mylonite) observed on Barangay Mauswagon, Godod, ZdN.

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