Portugal is a significant European minerals producer and is ranked among Europe's leading copper producers. The nation is also a notable producer of tin, tungsten and uranium. However, the country lacks the potential to conduct hydrocarbon exploration and aluminium, a limitation that has hindered the development of Portugal's mining and metallurgy sectors. Although the country has vast iron and coal reserves—mainly in the north—after the 1974 revolution and the consequent economic globalization, low competitiveness forced a decrease in the extraction activity for these minerals. The Panasqueira and Neves-Corvo mines are among the most recognised Portuguese mines that are still in operation.[citation needed]
What event triggered a decrease in the extraction of Portugal's natural resources?
1974 revolution and the consequent economic globalization