Topo Volcanic Complex

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Volcanic Complex of Topo(Complexo Vulcânico do Topo)
Massif (Maciço)
Montanhas do Complexo Vulcanico do Topo, Topo, Vila da Calheta, ilha de Sao Jorge, Acores.JPG
A view of the mountainous hills of the Topo Volcanic Complex
Official name:Complexo Vulcânico do Topo
Named for: Topo
Country Flag of Portugal.svg  Portugal
Autonomous Region Flag of the Azores.svg  Azores
Islands Eastern Group
Location Azores Platform, Mid-Atlantic Ridge, Atlantic Ocean
Municipalities Calheta
Coordinates 38°34′26″N27°51′43″W / 38.574°N 27.862°W / 38.574; -27.862 Coordinates: 38°34′26″N27°51′43″W / 38.574°N 27.862°W / 38.574; -27.862
Highest point Pico da Barrosa
Lowest point Sea level
 - location Atlantic Ocean
 - elevation 0 m (0 ft)
Biomes Temperate, Mediterranean
Geology Alkali basalt, Tephra, Trachyte, Trachybasalt
Orogeny Volcanism
Period Holocene
Locator map Azores Sao Jorge.png
Red pog.svg
Location of the complex on the island of São Jorge

Volcanic Complex of Topo (Portuguese : Complexo Vulcânico do Topo) is a complex of scoria cones and volcanic structures, located near the village Topo in the southeastern part of the island of São Jorge, in the Portuguese archipelago of the Azores.

Portuguese language Romance language that originated in Portugal

Portuguese is a Western Romance language originating in the Iberian Peninsula. It is the sole official language of Portugal, Brazil, Cape Verde, Guinea-Bissau, Mozambique, Angola, and São Tomé and Príncipe. It also has co-official language status in East Timor, Equatorial Guinea and Macau in China. As the result of expansion during colonial times, a cultural presence of Portuguese and Portuguese creole speakers are also found in Goa, Daman and Diu in India; in Batticaloa on the east coast of Sri Lanka; in the Indonesian island of Flores; in the Malacca state of Malaysia; and the ABC islands in the Caribbean where Papiamento is spoken, while Cape Verdean Creole is the most widely spoken Portuguese-based Creole. A Portuguese-speaking person or nation may be referred to as "Lusophone" in both English and Portuguese.

Topo (Calheta) Civil Parish in Azores, Portugal

Topo, also known as Nossa Senhora do Rosário, is a freguesia on the northeastern corner of the municipality Calheta on the island of São Jorge. It is considered the first settlement on the island of São Jorge to attain the status of municipality; from 1510 to 1867 "Vila do Topo" was the municipal seat of Topo, which included the neighboring parish of Santo Antão. The population in 2011 was 508, in an area of 9.24 km².

São Jorge Island island of the Azores, Portugal

São Jorge is an island situated in the central group of the Azores archipelago and part of the autonomous region of Portugal. Separated from its nearest neighbors by the 15 kilometres (9.3 mi) Pico-São Jorge Channel, the central group is often referred colloquially as part of the Triangulo ("Triangle") group or just "The Triangle". São Jorge is a relatively long thin island with tall cliffs, whose 9500 inhabitants are concentrated on various geological debris fields (fajãs) along the north and south coasts; from east to west, the island is 53 kilometres (33 mi) long and, north to south, 8 kilometres (5.0 mi) wide: its area is 237.59 square kilometres (91.73 sq mi).

Contents

History

The view of the crater valley of the caldera of Santo Cristo, on the northern coast of the complex Caminho pedestre da Serra do Topo para a Faja de Santo Cristo, vista 3, Calheta, ilha de Sao Jorge, Acores.JPG
The view of the crater valley of the caldera of Santo Cristo, on the northern coast of the complex
The main roadway in the Topo complex between Nossa Senhora do Rosario and Santo Antao Serra do Topo, as montanhas sucedem-se a estrada sobe a mais de 900 metros de altitude, Calheta, ilha de Sao Jorge, Acores.JPG
The main roadway in the Topo complex between Nossa Senhora do Rosário and Santo Antão

The base of the Topo complex originated in numerous shield volcanoes, erupting from primordial fissural faults that ran along a northwest to southeast and east-southeast to west-northwest alignment. [1] These structures are only observed in the curvature of the higher turf cones, as far as 700 metres (2,300 ft) above sea level. These activities initiated around 600,000 years ago. [1] [2] [3] The island of São Jorge had its initial formation from the rising of magma along these fractures through the earth's crust, resulting in effusive volcanism from the area east of Ribeira Seca until Topo (from which it got its name).

Owing to age, continuous effusive eruptions occurred simultaneously with the eruption on the island of Faial, along the Volcanic Complex of Ribeirinha. [1] Volcanism in this zone continued, with some interruptions over the next 500,000 years approximately. [1] But, continuous erosion, from coastal action, humidity and rainfall, wind and thermal amplitudes, resulted in an interior relief forming a more gently appearing landscape, in comparison to the western areas of Ribeira Seca. [1]

Geography

The volcanic complex occupies the eastern part of the island and consists of basalt lavas, hawaiite and mugearite (aa) lavas, from explosive pyroclastic rocks and cinder cones originating from Strombolian eruptions.

Basalt A magnesium- and iron-rich extrusive igneous rock

Basalt is a mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. More than 90% of all volcanic rock on Earth is basalt. Basalt lava has a low viscosity, due to its low silica content, resulting in rapid lava flows that can spread over great areas before cooling and solidification. Flood basalt describes the formation in a series of lava basalt flows.

Hawaiite is an olivine basalt with a composition between alkali basalt and mugearite. It was first used as a name for some lavas found on the island of Hawaii.

Mugearite Oligoclase-bearing basalt, comprising olivine, apatite, and opaque oxides

Mugearite is a type of oligoclase-bearing basalt, comprising olivine, apatite, and opaque oxides. The main feldspar in mugearite is oligoclase.

Its features around the complex includes the Pico do Brejo do Cordeiro and several others.

Pico do Brejo do Cordeiro is a peak on the island of São Jorge in the Azores.

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References

Notes
  1. 1 2 3 4 5 "A História Geológica de São Jorge I: O Início" (in Portuguese). Ponta Delgada (Azores), Portugal. 17 September 2008.
  2. G. Féraud et al. (1980), p.276
  3. "São Jorge: Vulcanismo Historico" (in Portuguese). Ponta Delgada (Azores), Portugal: entro de Vulcanologia e Avaliação de Riscos Geológicos da Universidade dos Açores/Centro de Informação e Vigilância Sismovulcânica dos Açores.
Sources