Geological Evolution and Relief of Argentina

Geological Evolution of the Argentine Territory

The Argentine territory belongs to the South American plate. Its geological history is divided into several eras:

Precambrian and Paleozoic Eras

• Precambrian: Divided into two ancient massifs: the Brasilia massif to the north and Patagonia to the south of the Colorado River valley, extending to the Chacopampeana plain.
• Paleozoic Basement: Characterized by the folding and uplift of sediments, forming the Eastern Cordillera and the Precordillera of La Rioja, San Juan, and Mendoza.

Mesozoic and Cenozoic Eras

• Mesozoic Era: During this time, the ranges were subjected to intense erosion. This era saw the folding of the Patagonides and Ventania systems.
• Cenozoic Era (Tertiary Period): Marked by the Andean orogeny, which caused the folding of the sub-Andean mountains and the rise of the Main Cordillera and the Patagonian-Fuegian Andes. It also caused the fracturing and re-elevation of the Puna, Eastern Cordillera, Tandilia, Ventania, and Sierras Pampeanas.
• Quaternary Period: Characterized by high relief erosion and the accumulation of sediment layers in sunken areas, such as the Plains of La Plata.

Geomorphological Factors

Exogenous and Endogenous Agents

The relief is modeled by various factors:

• Exogenous Factors: Modeling through weathering, destruction of rocks, thermal amplitude, and expansion/contraction in arid zones, the Patagonian highlands, and the Central Andes.
• Erosion Types: Wind erosion in arid areas; River erosion in the Mendoza Andes; and Glacial erosion in the Patagonian Andes and Tierra del Fuego.
• Accumulation: The carrying and deposition of material.
• Endogenous Agents: Volcanism, epirogenesis, seismicity, and orogenesis.

Main Relief Forms in Argentina

Plains and Plateaus

• Chacopampeana Plain: Occupies the east of the country down to the Colorado River. It has a Precambrian base covered by sediments. It is a fractured relief with ups and downs, featuring sedimentation in a temperate climate.
• Puna Plateau: Located at 3,000 m of altitude; it is of Precambrian origin and was promoted by the Andean orogeny.
• Missionary Plateau (Misiones): Characterized by fracturing and erosion caused by the Paraná and Uruguay rivers.
• Patagonian Plateau: Of Precambrian origin with marine sediment cover, affected by epirogenic movements and erosion caused by ancient rivers.

Mountain Systems

The mountain relief is formed by the Andean mountain range to the west. It includes the Central Andes, the Puna highlands, and the foothills of San Juan, Mendoza, and La Rioja, as well as the low sub-Andean hills and the Sierras Pampeanas.

Climatic Influence and Wind Distribution

The distribution of relief forms has significant consequences for the climate:

• Atlantic Winds: Moist winds from the Atlantic favor the flat relief, only being stopped by the mountains in the north, specifically the Eastern Cordillera and the Aconquija system.
• Pacific Winds: Moist Pacific winds are stopped abruptly by the Cordillera of the Andes.
• Human Importance: Unlike in Tropical America, where plateaus are the seat of important populations, the plateaus in Argentina are of less human importance.