Yucamane
Yucamane, Yucamani or Yucumane is an andesitic stratovolcano in the Tacna Region of southern Peru. It is part of the Peruvian segment of the Central Volcanic Zone, one of the three volcanic belts of the Andes generated by the subduction of the Nazca plate beneath the South America plate. Peru's active volcanoes Ubinas, Sabancaya and El Misti are also part of the Central Volcanic Zone.
Yucamane, together with the volcanoes Yucamane Chico and Calientes farther north, forms a Pleistocene volcanic group. Yucamane is constructed mainly by lava flows with subordinate pyroclastic deposits, and it has a well preserved summit crater with fumarolic activity.
The volcanic group was active in the Pleistocene epoch, with the Holocene featuring several explosive eruptions occurring at Yucamane proper and effusive eruptions at Calientes. The last dated eruption of Yucamane occurred 1,320 BCE; whether there were historical eruptions is unclear as some eruptions attributed to Yucamane probably took place at Tutupaca.
Geography and geomorphology
Yucamane lies in the Tacna Region, Candarave Province, Candarave District of Peru, west of lake Vilacota. The town of Candarave lies - southwest from the volcano and the city of Tacna south. A number of mostly agricultural towns exist on its slopes, such as Aricota, Cairani, Camilaca, Cucachi, Huanuara, Morjani, Pallata, Susapaya, Tarata, Ticaco, Totora and Yucamane Pampa, as well as irrigation infrastructure and major roads. Sulfur was mined on the volcano in the past.The area of Yucamane is accessible by a number of roads including the international Ilo-Desaguadero highway, and a road leads up the northwestern flank of Yucamane to a point close to the mountain pass between Yucamane and Calientes. The edifice of the volcano and surrounding region are part of the Vilacota-Maure protected area.
Regional
The Andes are the longest mountain range on Earth, extending from the Tierra del Fuego archipelago in southernmost South America to Venezuela in the north. In southern Peru, the Andes consist of several mountain chains including the Western Cordillera and the Eastern Cordillera, with elevations of up to, which are separated from each other by the Altiplano.More than 2,000 volcanoes exist in the Andes, mainly in the countries of Argentina, Bolivia, Chile, Colombia, Ecuador and Peru. Seven volcanoes have been active in Peru since the arrival of the Spaniards, but volcanic activity is typically poorly recorded in Peru, owing to the remote nature of the region and the scarce population.
Yucamane is part of the Central Volcanic Zone, one of the three major volcanic belts in the Andes, which spans the countries of Peru, Bolivia, Chile and Argentina. In Peru about four hundred heavily eroded volcanoes make up the volcanically active area along with the active volcanoes El Misti, Sabancaya and Ubinas; the volcanoes Andagua volcanic field, Casiri, Chachani, Coropuna, Firura, Huaynaputina, Tutupaca and Yucamane may have been active in recent history. The largest historical eruption in Peru occurred in 1600 at Huaynaputina and caused 1,500 fatalities and severe economic damage. Other major eruptions occurred 2,000 years before present at El Misti volcano, 1,000 years before present at Ubinas and two centuries ago at Tutupaca. Finally, the three volcanoes Ampato, Chachani and Coropuna have heights exceeding.
Local
Yucamane is a mountain whose height is variously given as, or. It is a high compound volcano, with an about wide summit crater; this depression in turn has a smaller crater with a diameter of and a depth of about nested within. The summit crater has a young appearance, and due to the youth of the volcano there is little trace of glaciation. Yucamane has a conical shape and is formed primarily by lava flows with some block and ash flows and pyroclastic flows. Lava flows are thick and often show characteristic flow ridges. They are especially prevalent on the upper western and upper southern flanks of the volcano, while the eastern flank has a higher proportion of pyroclastic flows, as does the far southern flank. Based on slope angle, a "Yucamane I" volcano, which forms the lower part of the volcano and has a more gentle slope, has been distinguished from a "Yucamane II", which sits atop "Yucamane I" and has steeper slopes. The lower part of the volcano bears traces of glaciation, presumably from the last glacial maximum. The edifice rises on a gently sloping plain between the Callazas and Calientes rivers. On the southeastern flank a secondary volcanic centre, high Mal Paso, can be found. This cone is wide and has a partially destroyed crater.Several other volcanoes lie north of Yucamane, such as the, or high Yucamane Chico and the, or high Calientes, which form a long north-south volcanic chain with Yucamane. Calientes and Yucamane are considered to be a paired volcano with a volume of and a base area of. Other volcanoes in the area include San Pedro, López Extraña and the much older Nazaparco. Nazaparco consists of andesitic rocks and rhyolitic block and ash flows, while Yucamane Chico and Calientes are surrounded by radially extending lava flows like Yucamane proper and Calientes has produced a ignimbrite south of Yucamane. Calientes has a wide summit crater with a lava dome complex and a long presumably glacial valley filled with the most recent lava domes. While its upper sector is well preserved, the lower flanks like the older volcanoes are eroded. The older volcanoes show evidence of sector collapses and have been glaciated, which has left moraines at elevations of about and glacial deposits with a volume of about. This volcanic complex is part of the Cordillera del Barroso mountain chain in southern Peru.
A series of northwest-southeast trending normal faults runs along the Andes close to Yucamane. The Yucamane fault runs in a north-south direction across the volcanoes, and another fault that runs northwest-southeast is named the Yucamane Chico fault; the Yucamane Chico volcano roughly coincides with the intersection of these faults.
Hydrology
The slopes of the volcano drain westward, eastward and southward towards the Calientes and Callazas rivers in the east and west of Yucamane, respectively. Both rivers flow southward and ultimately join to form the Locumba river, which ends in the Pacific Ocean. The water in these rivers contains large quantities of arsenic derived from volcanic rocks, including Yucamane's volcanic rocks; arsenic in drinking water is linked to internal organ damage and cancer.Geology
Off the western coast of South America, the Nazca Plate subducts beneath the South America Plate at a rate of about. This subduction process is responsible for the volcanic activity in the Andes. The subducting slab releases fluids which induce the formation of melts which are then erupted on the surface as volcanism. The subduction process is not uniform along the plate margin; variations in the dip of the subducting Nazca plate occur along its length, and volcanic activity is concentrated in three belts where the angle of subduction is steep enough.Volcanism in the region has been active since the Jurassic, with remnants of the oldest volcanic arc recognizable in the Peruvian Coastal Cordillera. During the Miocene epoch, volcanic activity occurred along the entire length of Peru; Pliocene-Pleistocene activity on the other hand is confined to southern Peru as part of the Central Volcanic Zone, with volcanic centres concentrated in the Western Cordillera. Volcanoes in Peru were first catalogued in 1962 and 1966, with a major compilation being published in 1991 by De Silva and Francis. These volcanoes include composite volcanoes, ignimbrites, lava domes and lava flow fields.
Yucamane is constructed on a basement formed by the Paleozoic Tacaza Group, the Jurassic Yura Group, the Neogene volcanic Huaylillas formation and the 10-1 million years old Barroso Group; parts of this basement crop out on the southern side of Yucamane. This basement in turn consists of two major tectonic blocks, the southern Arequipa terrane and the northern Paracas massif; both are formed by igneous and metamorphic rocks such as gneiss and are covered by Mesozoic sedimentary and Cenozoic volcanic rocks. A large ring-shaped volcanic intrusion appears to underlie Yucamane.
Petrology
Yucamane has erupted andesite, basaltic andesite, trachyandesite and dacite, which define a potassium-rich calc-alkaline suite. The andesites make up the bulk of the outcropping edifice. These andesitic rocks contain phenocrysts of amphibole, biotite, hornblende, oxides, plagioclase and quartz. Calientes has produced a similar rock suite but with a dominance of dacite instead of basaltic andesite and andesite as in Yucamane. The magmas formed through the assimilation of crustal material and fractionation of amphibole. Arsenic in volcanic rocks causes water pollution in rivers around Yucamane.Climate and natural features
The region has a dry tropical climate, with precipitation on Yucamane amounting to about. Most of it falls during the summer months, and the amount of precipitation decreases southwestward towards the coast and away from the mountains. After precipitation events the mountain is sometimes covered with snow. Because of the scarcity of precipitation, the volcanoes are relatively uneroded. Above elevation temperatures are almost always freezing, and while at elevation daily temperatures can reach night frosts are normal.Vegetation around the volcano includes a humid tundra with overall low vegetation density on its upper slopes, and paramo and montane steppe vegetation east/west and south of the volcano on its lower slopes, respectively. Quenoa woods have been observed on its flanks, which are otherwise covered by pastures lower on the volcano. The volcano is part of the. The scorpion species Brachistosternus ninapo is named after the volcano; the term ninapo is a portmanteau of the Quechua word for "fire-spitting mountain". This scorpion was discovered on the sides of the volcanoes Yucamane and El Misti.