METHODOLOGY

Pre-field

Crash courses and lectures on essential topics related to the geology of Palawan were given to allow the students to have a solid understanding of what to expect on site. The topics discussed include the structural geology of Southern Palawan, Karst and drainage geomorphology, ophiolites and ophiolitic sequences, and laterite deposits. These subjects were considered essential to the investigation of the study area as based on previous literature. Field techniques learned in previous geology courses were refreshed and in addition to this, the students were taught direct plotting with the use of a protractor-ruler and some field photography techniques. Medical concerns were also prioritized by giving seminars on first-aid training and possible biohazards in Palawan with emphasis on treatment and prevention.

For field preparation, the students were grouped into four (4) committees Mapping, Literature, Documentation, and Logistics. The Mapping Committee was tasked to prepare National Mapping and Resource Information Authority (NAMRIA) and Synthetic Aperture Radar (SAR) maps to be used in the traverse. The Literature Committee searched for papers and previous works on the study area such as its general geology, geomorphology, geochemistry, geophysics, paleontology, petrology, stratigraphy, structural geology, mineralogy, laterites, and ophiolites. The Documentation Committee prepared letters addressed to government officials and other authorities for legal concerns. Furthermore, they also did research on possible biohazards in Palawan and disseminated these information to the class. Lastly, the Logistics Committee was responsible in managing the supplies that will be needed in the fieldwork.

On site

The fieldwork was conducted by the Geology 170 class of 2014 from May 7-16, 2014. A peg system was used to coordinate daily groupings. The pegs are selected persons that are fixed and stationed into a permanent group number and are responsible with keeping all the field materials including tape measures, sample picks, Brunton compasses and maps while in the camp. Eighteen (18) students were assigned as pegs of groups with four (4) members each. The other students were randomly assigned into different groups with fixed pegs each field day. Each group was tasked to do mapping in selected areas each day. The faculty and students underwent reconnaissance surveys to choose areas with good exposure of outcrops that the field mapping team will traverse in. The outputs expected after a day of fieldwork include plot of the traverse and notes on the lithological units and structures observed in the field. These findings were reported to the rest of the class at night.

The field mapping was mainly executed through compass-tape traverse, employing the use of the clinometer if there is a slight change elevation in the area concerned. If mapping using compass-tape traverse is not possible mostly due to rugged terrain or time constraints, Global Positioning System (GPS) tracking and waypoints were used instead. The datum recommended for tracking GPS coordinates was Luzon Datum for positioning with higher precision and accuracy. Some of the coordinates were recorded using the World Geodetic System 1984 (WGS84) datum but were later converted into their Luzon Datum values. Exposures seen along the traverse were observed with extreme detail especially noting lithologic and structural information. Data obtained in the field were directly plotted in a 1:5,000 NAMRIA map. The rock samples obtained in the field were required to be at least fist-sized and must not be weathered. These samples were named according to their general location, grid on the map where it was taken, name of the peg that acquired that sample, date, outcrop number and sample number. The naming of these samples follows the format below.

[GENERAL LOCATION]-[GRID CODE]-[FIRST THREE INITIALS OF THE ASSIGNED PEG]-[DAY WHEN SAMPLE WAS ACQUIRED]-[OUTCROP NUMBER].[SAMPLE NUMBER]

Fieldwork consolidation activities on site include naming and sorting of samples, updating the class database which contains samples information, outcrop details, structural readings and pictures, and plotting the field data on 1:20,000 maps (Canipan and Bulaloc Quadrangles) for accomplishing lithologic and structural maps.

Post-field

Macroscopic descriptions of rock samples were improved for the sample database. Petrographic examination of samples followed after thin sections of the rock samples were prepared. The point counting method was used in thin section analysis for more accurate estimates on volume percentages and rock identification. A brief petrogenesis was also inferred for each sample. Figures, pictures and structural measurements were all sorted and compiled into a database to assist in report writing. Structural measurements were plotted into stereonets and Rose diagrams to highlight any structural trend present.

Conventions used in naming formations and suites were decided upon by all the working committees. The lithologic and structural maps were finalized as all information from the database were plotted. The distribution of laterite deposits was also traced resulting into an isopach map. Finally, a digitized base map was produced. Software used in digitizing the maps include Google Earth, Global Mapper, Quantum GIS, Adobe Photoshop, Digital Surface Model and Digital Elevation Model. Cross-sections of the area which best show all the lithologies and major structures observed in the field were accomplished, as well as a fence diagram for the general stratigraphy of the area. The final requirement of the course was a geologic paper integrating all the synthesized results of the field mapping.