There's any relevant resource in Patagonia that it is worth the trouble?
Besides, Portugal was in a pretty unstable situation after the Brazilian independence.
http://www.britannica.com/EBchecked/topic/446174/Patagonia/41675/Climate
Resource exploitation
The oil fields around
Comodoro Rivadavia and near Neuquén contain most of Argentina’s reserves, and natural gas also has been found in these two areas; these are Patagonia’s most valuable mineral assets. In addition, deposits of iron ore are worked at Sierra Grande, and some coal is mined in the south near Río Turbino. Other mineral deposits include manganese, tungsten (wolframite), fluorite (calcium fluoride), lead, heavy spar (barite, the principal ore of barium), copper and gold, vanadium, zinc-lead ore, and uranium. There also are deposits of kaolin and gypsum.
Dams have been constructed on the
Neuquén and
Limay rivers in order to exploit the hydroelectric potential of the western portion of Patagonia. These projects also have created large reservoirs that have made extensive irrigated agriculture possible in the Negro River region. Among the major crops grown are peaches, plums, almonds, apples, pears, olives, grapes, hops, dates, vegetables, aromatic plants, and alfalfa. Sheep raising is an important economic activity in Patagonia, although in the early 21st century overgrazing was a growing concern.
Tourism has become important since the end of World War II, as wildlife reserves and the national parks located along the Patagonian Andes have brought in growing numbers of those seeking recreation. There also has been an increase in scientific study (e.g., glacier research) and in detailed mapping and surveying for mineral exploitation.
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They could hold onto it by mining coal and iron with sheep raising until they can exploit natural gas.