Week 5 - Samuel O'Connell (The Andes)

This week I chose to visit the oceanic/continental crust convergent boundary of Nazca plate and the South American plate, also know as the Andes Mountains. This subduction zone of mountain belts is relatively young, less than 100 million years old.  These mountains are actually the longest continental mountain range in the world, and spread through seven different South American countries, with a range over over 5500 miles. There are also several high plateaus with major cities established. Plateaus usually form from magma  pushing towards the crust but not breaking through, which leaves the flat, large areas of rock raised upwards. 

As the region is so large and is the result of both faulting and folding from compression, I chose to narrow my travels to Mount Aconcagua, the tallest mountain in the western hemisphere. The fellow travelers tell me that Aconcagua was once an active stratovolcano, before the angle of subduction f the Nazca plate began to decrease, which resulted in horizontal stresses that have created the thrust faults we can observe today. Along with this pattern of thrust faults has been observed a tendency of folding as well, and is referred to as 
the Aconcagua thrust and fold belt. These thrust and fold belts are caused from the newer front of the belt thrusting, while the older, inactive belts fold. 

The main rock deposit present at Aconcagua was actually first noted by Charles Darwin in 1835. He observed mainly rocked that have been determined to be volcanic andesite. Also present are sedimentary rocks  that have been dated to 300 million years ago. Sedimentary mesozoic rocks have deformed and are thought to have caused the folds located in the region. 






https://www.aconcaguatreks.co.uk/geography-altitude.html
https://www.researchgate.net/figure/a-Geological-map-of-the-Aconcagua-fold-and-thrust-belt-in-the-Yeso-and-Palomares-river_fig4_286202749