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 <answer>1974 revolution and the consequent economic globalization</answer>, 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