Discovering the Enigma of Payún Matrú
Imagine a colossal sleeping giant, its form sculpted by time and tectonic forces, nestled in the heart of Argentina’s Mendoza Province. This is Payún Matrú, a shield volcano that has been shaped over millions of years through the subduction of one plate beneath another.
The name ‘Payún Matrú’ translates to ‘bearded goat,’ reflecting its rugged and wild appearance. But what lies beneath this majestic form? A complex geological history, with layers upon layers of volcanic activity that have shaped the landscape over time.
Geological Marvels
How did Payún Matrú come to be? The volcano developed on sediment and volcanic rocks from Mesoproterozoic to Tertiary periods. Its formation is a testament to the dynamic nature of our planet, where tectonic plates move and interact, creating landscapes that can inspire awe and wonder.
The Payún Matrú volcanic field consists of diverse landforms including a large shield volcano, calderas, high compound volcanoes, scoria cones, lava flows, and ignimbrites. The caldera, which once spanned 8-9 km wide, now stands as a reminder of the immense power that lies within this geological wonder.
Volcanic Activity Through Time
The volcanic activity at Payún Matrú began during the Plio-Pleistocene period and continued until about 515 years ago. This continuous cycle of eruption and cooling has left behind a rich tapestry of rock formations, each telling its own story.
Among these are the Pampas Onduladas lava flow, which is the longest Quaternary lava flow on Earth, stretching over 167-181 km. This flow, originating from the La Carbonilla fault, moves across a gentle terrain, covering everything in its path with layers of molten rock.
Geological Diversity
The volcanic field contains about 300 individual volcanic vents, each with unique morphologies such as fissure vents, lapilli cones, scoria cones, and strombolian cones. These diverse formations contribute to the rich geological diversity of Payún Matrú.
Among these are the Plio-Pleistocene Morados Grandes east and the cones around Pihuel volcano northeast of the field; the Guadalosos, La Mina, and Montón de Cerros cones in the northern part of the field; and the Holocene cones in the eastern and western parts. Each one tells a story of its own, contributing to the overall narrative of this volcanic landscape.
Volcanic Rocks and Eruptions
The rocks erupted at Payún Matrú are diverse, ranging from alkali basalts over basalts, trachyandesite, basaltic trachyandesite, trachybasalt, and trachyte to rhyolite. These eruptions have been inferred to originate during partial melting of enriched mantle, with subsequent crystal fractionation, assimilation of crustal material, and magma mixing in magma chambers.
The edifice of Payún Matrú acts as an obstacle to magmas ascending to the surface, resulting in only evolved magmas being erupted within the caldera area. Basic magmas, on the other hand, reached the surface mainly outside of the main edifice, creating a complex and fascinating geological landscape.
Climate and Ecosystem
The climate at Payún Matrú is cold and dry with strong westerly winds. Annual temperature varies between 2 and 20 °C (36 and 68 °F), while the average annual precipitation amounts to 200-300 mm/a (7.9-11.8 in/year). Despite these harsh conditions, the area supports a unique ecosystem characterized by sparse bushes, herbaceous vegetation, and few trees.
Representative plant genera include Opuntia cactus and Poa and Stipa grasses. The landscape is home to various animals such as armadillos, black-chested buzzard-eagle, condors, Darwin’s rhea, guanaco, mara, Pampas fox or South American gray fox, puma, and Southern viscacha.
Human Interaction
Obsidian from Payún Matrú has been found in archeological sites, although its use was not widespread in the region. The volcano is also notable for large crystals of hematite pseudomorphs which originated in fumaroles. These unique geological features have contributed to the rich cultural heritage of the area.
Conclusion
The geological history of Payún Matrú is a fascinating journey through time, with layers of volcanic activity that have shaped this landscape over millions of years. From its formation during the Plio-Pleistocene period to its most recent eruptions just 515 years ago, each layer tells a story of the dynamic forces at work beneath our feet.
Payún Matrú stands as a testament to the enduring power and beauty of nature, inviting us to explore and understand the complex geological processes that shape our world. As we continue to study this volcanic field, we uncover not only its past but also gain insights into the future of our planet’s ever-evolving landscape.
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This page is based on the article Payún Matrú published in Wikipedia (retrieved on March 11, 2025) and was automatically summarized using artificial intelligence.
