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| Payún Matrú | |
|---|---|
| Name | Payún Matrú |
| Elevation m | 3696 |
| Location | Mendoza Province, Argentina |
| Range | Andes |
| Type | Shield volcano complex |
Payún Matrú is a large volcanic complex in the southern Andes of Argentina, located in Mendoza Province. It is a prominent feature of the Payenia volcanic province and forms part of the Quaternary volcanic arc influenced by the subduction of the Nazca Plate beneath the South American Plate. The complex includes multiple shields, scoria cones, lava flows and a nested caldera system, and has been the subject of studies by researchers from institutions such as the Smithsonian Institution, Geological Survey of Argentina, and various universities.
The complex sits on the Pampean flat-slab-influenced segment of the Andean orogeny within the Valle Grande region near the Malargüe Department and is proximal to features like the Llancanelo Lake and the Desaguadero River drainage. Regional tectonics reflect interactions among the Nazca Plate, South American Plate, and subduction-related structures including the Mendoza Fracture Zone and the Pampean flat slab. The edifice overlies basement composed of Cretaceous and Paleozoic sediments and plutons related to the Cuyo Basin and the Sierras Pampeanas uplift. Volcanological mapping by teams from the University of Buenos Aires and the CONICET has defined multiple eruptive centers distributed over a broad plateau.
The volcanic complex is composed of several overlapping shield volcanoes, a nested caldera several kilometers across, extensive ʻaʻā and pāhoehoe-like lava fields, and numerous scoria and spatter cones. Key landforms include a summit caldera that hosts collapse structures reminiscent of calderas at Aso, Toba, and Bowie Seamount in scale relationships, although smaller. Satellite imagery from Landsat and ASTER sensors and fieldwork employing GPS and LiDAR have documented flow lobes extending tens of kilometers, radial rift zones similar to those at Kilauea and structural fissures comparable to the rift systems at Iceland's Vatnajökull margins. Pyroclastic deposits, lava tubes, and pahoehoe sheet flows are juxtaposed with blocky ʻaʻā in distal facies.
Stratigraphic studies supplemented by radiometric dating (principally K–Ar and 40Ar/39Ar) indicate activity spanning the Late Miocene to the Holocene, with the main shield-building phase in the Pleistocene. Key eruptive pulses have been correlated with regional ignimbrite events documented in the Andean Central Volcanic Zone and with distal tephra layers recognized in cores analyzed at institutions such as the Geological Survey of Argentina and the Smithsonian Institution. Chronological constraints place younger centers' activity in the Late Quaternary, and geomorphological evidence suggests some vents produced flows in the Holocene, comparable in preservation to Holocene flows at Llullaillaco and Tupungato. Paleomagnetic and geochronological syntheses by teams from the Universidad Nacional de Cuyo have refined a multi-stage eruptive model.
Lavas range from olivine‑bearing basalts to more evolved basaltic andesite compositions, with mineral assemblages that include olivine, pyroxene, and plagioclase. Geochemical signatures show enrichment in incompatible elements and variable Sr–Nd–Pb isotope ratios, interpreted as reflecting mantle source heterogeneity and varying degrees of crustal assimilation analogous to patterns described for the Southern Volcanic Zone and the Back-arc basalts of southern Chile. Trace-element studies using XRF and ICP-MS performed by laboratories at the Universidad Nacional de La Plata indicate affinities with intraplate alkaline basalts in some units and more arc-like calc-alkaline trends in others, implying a complex magmatic evolution involving fractional crystallization and magma mixing processes observed at complexes like Chacana and Maipo.
The complex lies within an arid to semi-arid highland environment influenced by the South American monsoon and westerly Roaring Forties-derived storm tracks. Vegetation zones include high-Andean steppe dominated by Festuca grasslands and shrubs adapted to xeric conditions, with faunal assemblages including species recorded in regional surveys by the Instituto Nacional de Tecnología Agropecuaria and the Museo Argentino de Ciencias Naturales. Climate data from nearby stations maintained by the Servicio Meteorológico Nacional document low annual precipitation, large diurnal temperature ranges, and strong radiation, factors that influence soil development on basaltic substrates and the distribution of endemic and migratory species similar to those catalogued in the Monte Desert ecoregion.
The volcanic plateau has archaeological evidence of hunter‑gatherer and pastoralist use, with lithic scatters, rock art, and occupation sites studied by archaeologists at the Consejo Nacional de Investigaciones Científicas y Técnicas and the Universidad Nacional de Cuyo. Prehistoric human activity includes traces contemporary with regional cultural phases recognized at sites associated with the Diaguita and Huarpe cultural traditions, and later historic-era use during Spanish colonial expansion centered on settlements like Alvear and Malargüe. Ethnohistoric and archaeological work connects mobility corridors across the volcanic terrain to trade networks involving the Mapuche and other indigenous groups documented in colonial records archived by the Archivo General de la Nación (Argentina).
Parts of the volcanic complex and surrounding landscapes fall within provincial conservation initiatives and are adjacent to protected areas such as the Llancanelo Provincial Reserve and provincial parks managed by Mendoza Province authorities. Conservation efforts involve collaborations among CONICET, provincial environmental agencies, and NGOs active in Andean conservation like Aves Argentinas and the World Wildlife Fund. Management priorities address volcanic geomorphology preservation, biodiversity conservation consistent with Ramsar Convention-linked wetland stewardship at nearby lakes, and sustainable tourism practices informing regional planning by the Ministry of Tourism of Argentina.
Category:Volcanoes of Mendoza Province Category:Shield volcanoes Category:Volcanic fields of Argentina