Decoding the mysteries of the Puna and the Cordillera Oriental
La Quiaca – a small village of Argentina located in the north directly at the border to Bolivia. Hundreds of people are crossing the border every day, packed with boxes and carrying goods to sell on both sides of the national limit. Colorful fabrics, immense packages of plastic boxes and glittering toys, probably produced in an Asian country and shipped to South America, are packed to the ceiling of the small shops pinched across the maze of streets running through the city.
People with weathered faces and hands are sitting on the sidewalk guarding the shops and looking out for customers to come. The village with its ochre houses, estrays and framed by the mountains of the Puna plateau and the Cordillera Oriental sits on top of an eight million years old sedimentary deposit. The city is surrounded by this amazing landscape which inhibits trace of an immense lake system, hydrothermal veins and tectonic activity. Fault systems are running through the lithologic crust like the streets through La Quiaca. But like the people of the village the faults also show a certain pattern, oriented like the stream of customs from the north to the south. The evolution of the Andes created by the subduction of the Nazca plate under the South American Plate forms the typical north-south running faults. Preserved by the dry climate of the Puna the fault scarps are visible on the surface even after millions of years.
Decoding the evolution of the area is the work of my college and friend Gregor Lauer-Dünkelberg who also joined the StRATEGy team and who went with my on the field trip in 2018. As he invited me to his field work I was glad to be able to return the favor. Having more people in the field means automatically having more voices, thoughts, and opinions together, all of which can help you to develop an idea of the history of the area. Prosperous field work depends greatly on the chemistry of the people working together and our was joined by Johanna Diacono who starts to write her master theses about the area and works together with my supervisor Diego Winocur.
Luckily we encountered an interesting area in the south and east of the city of Abra Pampa for her. There we found up to 20 m high lake sediments which must have been developed due to a blockage of the draining route to the west. The likeliest possibility is that there was a huge landslide detached from the friable and strongly heavily jointed and folded Pirgua group, a lithology consisting of red sandstones.
I could already implement my knowledge about organic samples to this site as we found traces of peat bogs and thin layers of organic material. The area inhibits so many work and possibilities that I am thinking about returning and joining another campaign in September.
