Geological Mapping Field Trip and Ore Grade Calculation– Pituca Mine, Zamora Chinchipe, Ecuador

This field trip is aligned to a third-year undergraduate field course in Geological Exploration at the Loja Technical University, Loja, Ecuador. The target audience for this mapping experience is: upper-level undergraduate students of geology, with a platform of moderate understanding of rocks, minerals, and structural geology.

Students should have a moderate (i.e. above first-year undergraduate) understanding and knowledge of basic geological terms and processes, including: 1) common rocks and minerals; 2) a conceptual understanding of strike and dip; 3) proficiency in reading topographic maps and using geographic latitude/longitude coordinates; 4) a basic understanding of geospatial information and lab procedure.

Undergraduate geology curricula differ between institutions and instructors will be best able to determine how this field trip aligns to their institution's curriculum. At the Loja Technical University, 30-40 second-semester third-year (i.e. junior) successfully complete this learning experience every year. Prior to completing this exercise, these students will have passed several undergraduate geology courses, including coursework covering: a) ore deposits; b) geophysics; c) geochemistry; d) borehole logs; e) structural geology.

This field trip activity is positioned as a stand-alone geological map making exercise that is worth ~20% of course marks/grade in the second half of the semester in the Geological Exploration course in the Geosciences Department (School of Engineering and Architecture). At the Loja Technical University, 35% of course marks/grade is covered by a combination of the final exam and a CANVAS test. Trip was set up for week 13, lecture was given during week 14, lab work including sample preparation was performed during week 15 and 16 (during final exams).

Learning goals include: 1) Recognizing and recording the structure, and lithology of common rocks; 2) Feedback on the knowledge of sampling using the gold panning technique to concentrate the collected samples; 3) Creation of a geological map along the access road; 4) topographic survey of the underground mine gallery; 5) Identifying the mineralization in the study area through geological exploration; 6) writing a technical report on the lab and field results

1) Selection of the study area: Areas with a high probability of gold deposits, based on previous geological information and other geochemical studies.
2) Sampling: Sediment samples were collected in certain areas of the river using the gold panning technique, where there was presence of gold in certain samples, then they were labeled for laboratory analysis.
3) Laboratory analysis: A chemical analysis was carried out to determine the concentration of gold and other heavy metals.
4) Interpretation of the results: The results of the analyzes are interpreted to determine the location and concentration of the gold deposits.
5) Future exploration planning: Based on these results, future exploration and mining operations can be planned to confirm and advance gold production.

Materials required for field work in groups:
- Brunton compass
- Rock hammer
- Field notebook
- Steel pan to scoop alluvial deposits
- Hardness pencil
- GPS
- Tape measure

Bedrock consists of Precambrian, Mesozoic and Cenozoic rocks of diverse genetic environments. The geology of the Sub-Andean belt in southeastern Ecuador is dominated by type I batholith intrusions of the Zamora Intrusive Complex, defined by Jurassic continental arc. These rocks intrude pre-Jurassic rocks. The Misahualli Formation volcanics are the extrusive equivalent of the Jurassic continental arc.

Volcanoclastic rocks of the Triassic Piuntza Unit outcrop in tectonic windows above the Zamora Intrusive Complex. Sedimentary rocks of the Cretaceous Hollin and Napo Formations lie discordantly over the Zamora Intrusive Complex (INIGEMM, 2017).

Survey Data (Microsoft Word 2007 (.docx) 18kB Mar6 23)
Survey Data II (Microsoft Word 2007 (.docx) 19kB Mar6 23) 
Field Trip and Lab Workflow (Microsoft Word 2007 (.docx) 19kB Mar6 23) 

Student Photos -- educator-only file

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Exercises -- educator-only file

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Students must make a detailed bedrock geological map of the roadcut area around Pituca lease using ArcGIS and a topographic underground gallery using AutoCAD. Students often struggle with the geospatial tools to make a geological map in ArcGIS. They should also have a good background on how to write a solid technical report.

Students should be graded on the quality of the technical report.

• Quality of the Introduction, Background and Methodology section is worth 2 points. 
• Quality of the detailed mapping section is worth 2 points. 
• Quality of the Discussion and Interpretation Section is worth 2 points. 
• Quality of the graphs and figures presented is worth 2 points. 
• No grammatical errors is worth 2 points.
• For more information on the UTPL Geology program, visit https://www.utpl.edu.ec/carreras/geologia 

Juvonen, R., & Kontas, E. (1999). Comparison of three analytical methods in the determination of gold in six Finnish gold ores, including a study on sample preparation and sampling. Journal of Geochemical Exploration, 65(3), 219-229.

Guresin, N., Lorenzen, L., Dominy, S. C., Muller, H., & Cooper, A. (2012). Importance of effective sampling and test work protocols for process plant design. In Proceedings of Sampling Conference (pp. 95-107). Melbourne: Australasian Institute of Mining and Metallurgy.

Magalhães, F. B., de Freitas Carvalho, C., Carvalho, E. L. C. N., Yoshida, M. I., & dos-Santos, C. G. (2012). Rendering wastes obtained from gold analysis by the lead-fusion fire-assay method non-hazardous. Journal of environmental management, 110, 110-115.