Sun is shining. Perfect weather to be in the field. After breakfast, we start traveling from Uspallata to Rodeo – the most northern region of our trip. We expect a long day.
We enter the Calingasta-Uspallata-Iglesia valley and observe a wide intramontane basin. The basin is bound to the West by the snow covered Frontal Cordillera and to the East by the thrust and fold system of the Precordillera. We discuss the setting and style of this basin and try to find analogies to the observations we made one year ago in northwest Argentina. After reviewing the forces acting on the fault systems, we argue over the definitions of intermontane basins (again). Once we all “agree”, we make sure to eat all the apples since fruit fly concerns prevent their transport over the border between Mendoza and San Juan.
On the way to Calingasta we examine some Triassic deposits, green sediments that correspond to rift and lake deposits, which can be found in present-day East Africa. We help take a local man to the next town to receive medical support.
At the third stop we begin speaking about a paleolake deposit that is about 10,000 years old. We enter into a discussion about how this lake was generated. Three hypotheses are being debated: a) earthquakes, b) landslides or c) paleoclimate variability. In the end we mostly agree that an earthquake triggered landslide dammed the lake. Finally, the lake deposits were quickly eroded away.
Continuing the drive, we find ourselves between the Frontal Cordillera and Precordillera, and we see the youngest rocks and deposits from these tectonic provinces in the quaternary sediments.
It is now nearly nightfall, but before the sun sets we cross the internally drained Gualilan basin. After a long journey through these wonderful landscapes, we arrive at the Hotel in Rodeo and end the day in the swimming pool.
Text: Martin Zeckra, Federico Ibarra, Ornela Constantini, Juan Pablo Villalba Ulberich, Ahmad Arnous, Henry Wichura
Online published by: Daniela Großmann
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