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| Moquegua Basin | |
|---|---|
| Name | Moquegua Basin |
| Region | Moquegua Region |
| Country | Peru |
| Coordinates | 17°10′S 70°55′W |
| Area km2 | 15000 |
| Type | Forearc/retroarc sedimentary basin |
| Orogeny | Andean orogeny |
| Basin age | Neogene–Quaternary |
| Major resources | Copper, molybdenum, silver, groundwater |
Moquegua Basin is a Neogene–Quaternary sedimentary basin in southern Peru located within the Moquegua Region adjacent to the Pacific Ocean and the western margin of the Altiplano. The basin occupies part of the forearc/retroarc transition of the Andes and hosts important mineral deposits, complex stratigraphy, and a record of Andean tectonics and climate change. It is bounded by volcanic and metamorphic highs related to the Central Volcanic Zone and contains fluvial, marine, and lacustrine successions that record uplift, subsidence, and sediment supply variations linked to subduction of the Nazca Plate beneath the South American Plate.
The basin lies in the coastal hinterland between the city of Moquegua and the high plateau of the Altiplano–Puna Plateau, extending toward the Pacific Coastal Plain and the Islay Province. It is proximal to the confluence of drainage systems that include the Río Tambo and tributaries feeding into the Río Ilo, and is influenced by orographic barriers such as the Chilcayoc Hills and the Cordillera de los Andes. Regional connectivity links the basin to transportation corridors like the Pan-American Highway and to port infrastructure at Matarani and Ilo Port. Climatic regimes that affect the basin derive from interactions between the Pacific Ocean cold Humboldt current, the El Niño–Southern Oscillation, and highland precipitation patterns over the Altiplano.
Structurally the basin is controlled by back-arc and forearc geometry formed above an active convergent margin, with basin-bounding faults related to the Puno Fault System and the Batan Grande Fault transferring strain across the region. Stratigraphic successions include Paleogene volcanic and volcaniclastic units correlated with the Arequipa Massif basement, overlain by Neogene synorogenic clastics that contain conglomerates, sandstones, and siltstones comparable to sequences studied in the Sierra Nevada de Santa Marta and the Coastal Cordillera. Key mapped formations exhibit unconformities and growth strata linked to Andean uplift episodes recorded in the Altiplano Basin and the Maracaibo Basin. Basin depocenters host coarse-grained alluvial fans and axial fluvial systems analogous to deposits of the Santa Cruz Formation and marine incursions similar to those in the Pisco Basin.
The basin evolved during Neogene shortening and uplift associated with the Andean orogeny driven by the subduction of the Nazca Plate and modifications during episodes of flat-slab subduction observed beneath southern Peru and northern Chile. Tectonic events include Miocene transpressional deformation linked to the Incaic Phase and Pliocene–Quaternary basin inversion documented alongside regional structures such as the Sillapaca Fault and the Santiago del Estero Fault. Strike-slip partitioning and crustal thickening that affected the Bolivian Orocline and the Peruvian Andes influenced the basin’s accommodation space. Geophysical surveys compare Moquegua with the Lima Basin and the Talara Basin in terms of subsidence rates and heat flow related to magmatism of the Central Volcanic Zone.
Sedimentation records shifts between marine transgression-regression cycles influenced by sea-level change and tectonic uplift, producing shallow-marine, estuarine, fluvial, and lacustrine facies resembling successions in the Pisco Basin and the Urumaco Sequence. Provenance studies point to erosion of volcanic highlands akin to Misti and Ubinas volcanic centers, with detritus sourced from the Arequipa Massif and the Cordillera de Chila. Paleosols, channel-fill conglomerates, and overbank fines indicate alternating arid to semi-arid conditions modulated by episodes of strengthened moisture delivery during El Niño events and Pleistocene glacial cycles tied to the Last Glacial Maximum. Palynological and isotopic records from basin cores have been compared with records from the Lake Titicaca basin and marine terraces at Arica.
The basin and its margins are prospective for porphyry and epithermal copper–molybdenum–gold systems similar to deposits in the Cuajone District, Escondida, and Toquepala. Known occurrences include sulfide mineralization with chalcopyrite and molybdenite hosted in intrusive and volcanic sequences akin to those of the Andina and Antamina mining districts. Alluvial and groundwater resources supply agriculture in the Moquegua Valley and urban centers like Moquegua (city), supported by irrigation schemes comparable to those at Majes and Quebrada de los Pozos. Hydrogeological frameworks exploit aquifers within basin-fill sediments, with water rights and infrastructure tied to regional institutions such as the Autoridad Nacional del Agua.
Fossil assemblages within marine and terrestrial intervals include mollusks, marine vertebrates, and terrestrial mammals comparable to finds from the Pisco Formation and the Santa Cruz Formation of Patagonia. Marine faunas provide biostratigraphic markers analogous to those used at Santo Domingo de los Olleros and Ica, while terrestrial vertebrate remains record Quaternary faunal turnovers related to climate shifts documented in the Fuego-Patagonia region. Trace fossils and ichnofabrics in fluvial facies inform comparisons with paleoecological reconstructions from the Bolivian Altiplano.
Human occupation of the basin traces from preceramic settlements connected to highland societies such as the Wari and Tiwanaku cultural spheres, through Inca administrative integration and colonial-era ranching linked to land grants near Arequipa and Puno. Modern land use includes irrigated agriculture producing olives and grapes for export via ports like Ilo Port and urban expansion around Moquegua (city). Infrastructure projects intersecting the basin involve roadworks tied to the Pan-American Highway and water management initiatives coordinated with regional offices of the Ministry of Agriculture and Irrigation. Conservation and cultural heritage programs reference archaeological sites comparable to those protected in Sicuani and Cuzco.
Category:Geology of Peru Category:Basins of the Andes