Santo Antão (Cape Verde)

Santo Antão
	Satellite image
Waters	Atlantic Ocean
Archipelago	Ilhas de Barlavento
Geographical location	17 ° 4 ′ N , 25 ° 10 ′ W Coordinates: 17 ° 4 ′ N , 25 ° 10 ′ W
length	40 km
width	20 km
surface	779 km²
Highest elevation	Tope de Coroa ; 1979 m
Residents	47,124 ; 60 inhabitants / km²
main place	Porto Novo
	Map of the island

Santo Antão (Portuguese for Saint Anthony ) is the second largest of the Cape Verde Islands in the Atlantic at 779 km² . 47,124 people live on Santo Antão.

geography

Western Santo Antãos plateau after the rains of winter 2004/2005; Tope de Coroa in the background

Santo Antão is the northernmost and westernmost island of Cape Verde, belongs to the Ilhas de Barlavento (dt., Islands above the wind ') and is separated from the island of São Vicente in the south by a 16 km wide sea channel .

The high mountainous island of volcanic origin is characterized by mountainous landscapes with deeply cut erosion valleys in the north and somewhat flatter volcanic slopes to the south. Young volcanoes with wide caldeiras , sprawling white pozzolan hills and hundreds of meters high basalt rocks form dramatic volcanic landscapes. The largest mixed and coniferous forests of Cape Verdes are located on the heights of the eastern plateau . The northeast of the island is relatively rainy, while the southwest remains dry. The highest point is the Tope de Coroa (1979 m) in the desert-like west.

Administratively, the island is divided into three concelhos (districts), Paul , Porto Novo and Ribeira Grande . The port city of Porto Novo in the south has been the most populous settlement for a few years and has replaced the traditional village of Vila da Ribeira Grande .

geology

The geological development of Santo Antão can be divided into three phases (from young to old):

Young vulcanites
Intermediate vulcanites
Ancient volcanic rocks

The volcanic substructure of the island, which is below sea level , is likely to date back to around 16 million years BP (beginning of the Middle Miocene - Langhium ). It makes up around half of the total volume and lies on 119 to 118 million year old oceanic crust from the Lower Cretaceous ( Aptian ). The aboveground exposed ancient volcanic rocks go back to the Tortonian (7.5 million years BP), the main part of the sequence is essentially between 3 and 2 million years old ( Upper Pliocene - Piacenzian and Gelasian ). The predominantly subaeric old volcanic rocks form a large complex that extends from Chã Morte to the valleys of Escabecada , Tarrafal , Água Nova and Chã de Igreja . The volcanic rocks belong to the basanite / tephrite / phonolite differentiation series, with basanites predominating. Enriched basanites can be found in the lower Água Nova gorge. The ancient volcanic rocks were produced by a southwest-northeast trending dike school that crosses the central section of Chã Morte and the northern Ribeira Grande Valley.

The 2 to 0.3 million year old intermediate volcanic rocks of the Quaternary (early and middle Pleistocene ) can be divided into five groups:

In them, rocks of the more enriched nephelinite / phonolite differentiation series appear for the first time (with melilite nephelinites, nephelinites and phonolites). The 2 million to 1 million years old, Pleistocene Bordeira Group consists of a nephelinitic volcanic structure that was built in the western part of Chã Morte over a leveled volcano of the ancient volcanic rocks. The 1.4 to 0.7 million year old Cova group (also Old Pleistocene) is Basanitic and open in the Cova / Corda / Paul sector . In the period 0.7 to 0.3 million years BP, the Sinagoa volcano with the Cadela volcanic rocks formed in the central highlands . The nephelinitic and basanitic volcanic rocks were extracted through a crevice that had opened parallel to the old swarms in the southwest. Between 0.5 and 0.4 million years BP, the basanite Monte Frado volcano erupted in the south of the island, at about the same time the volcanic rocks of the Basanite Água Nova group were formed , but they lasted for 0.3 million years.

The 0.4 to 0.1 million year old and predominantly nephelinitic (Middle to Young Pleistocene) younger volcanic rocks can be divided into four groups:

The 400 thousand to 200 thousand a BP-old proto-Caroa group with their nephelinitischen Scoriakegeln and lavas is in the vicinity of Tope de Coroa found. At about the same time, the Junge-Tarrafal group , which also exhibits nephelinitic chemistry, was erupted via southwest-northeast trending fissure systems west of the Tope de Coroa . Between 200,000 and 170,000 years BP, the nephelinite lavas of the Coroa group were mined; they partly overlay the Proto-Coroa group.

In the period from 400,000 to 100,000 years BP, the nephelinitic Lagoa group penetrated into the central part of the island via fissure systems . In the central highlands, several rows of scoria cones were created along the columns. Lava flows from the fissures flowed to the southeast and reached the sea west of Porto Novo .

Around 200,000 years ago, there was a major Plinian eruption through a vent immediately south of the Coroa complex in the west of Santo Antão. The eruption left two phonolithische pumice - Horizonte back (CG 1 and CG 2), covered the first of the entire island and therefore for stratigraphic correlations of recent lavas of great value.

Most of Santo Antão's volcanic rocks come from lava flows of the two differentiation series mentioned. 10 to 20 percent of the lava flows are composed of picrites and ankaramites . Pyroclastics , predominantly lapilli and bombs, and some ignimbrites are often found near the eruption centers . The most voluminous part of the eruptions was the phonolithic pumice from Cão Grande .

Petrological model calculations point to a heterogeneous, peridotitic mantle rock that partially melted 1 to 4 percent at a depth of 90 to 125 kilometers. The more primitive magma types among the volcanic rocks found on Santo Antão are typical oceanic island basalts ( OIB ) dominated by a HIMU component . The older volcanic rocks vary between a young and a slightly less radiogenic HIMU component. The intermediate vulcanites represent a two-component mixture of a DM-like component and a young HIMU component that is close to the carbonatites . An old HIMU component dominates the young volcanic rocks. It is assumed that the magmas rose with the Cape Verde mantle plume , the temporal changes in the chemism are attributed to an internal change in the composition of the mantle plume .

history

Taken for Portugal by Diego Afonso in 1462 , the island was initially mainly used to harvest the dyer's lichen roccella tinctoria . In the 17th century, permanent settlers settled for the first time, including sons of landowners from the southern islands of Santiago and Fogo, as well as new settlers from northern Portugal under the Count da Cruz in today's Vila da Ribeira Grande . Wine, physic nuts and later also coffee determined the history of the island as the most important export products.

administration

The island belongs to the northern group of the Cape Verde Islands, the Ilhas de Barlavento . The most important place is Porto Novo .

Administratively, Santo Antão is divided into three districts ( concelhos ) with a total of seven parishes ( freguesia ).

Concelho (circle)	Freguesia (Municipality)
Ribeira Grande	Nossa Senhora do Rosario
	Nossa Senhora do Livramento
	Santo Crucifixo
	São Pedro Apóstolo
Paul	Santo António das Pombas
Porto Novo	São João Baptista
Porto Novo	Santo André

Economy and tourism

Main occupations are agriculture with the cultivation of sugar cane , yams , cassava , bananas , mango and corn and fishing . The most important agricultural product today is the island's white rum , known as grogue .

Tourism is slowly gaining in importance in the north. The impressive mountain landscapes make the island the most popular hiking region in Cape Verde. Since the small airport at Ponta do Sol was closed in 2003, the island can only be reached via the ferry connection Mindelo (São Vicente) - Porto Novo (Santo Antão) (up to four times a day). A new regional airport southwest of Porto Novo is being planned.

Personalities

Roberto Duarte da Silva (1837-1889), chemist
Luís Romano (1922-2010), writer, published short stories in 1973 under the title Negrume / Lzimparin in the Creole of Santo Antãos with Portuguese translation
Amaro Alexandre da Luz (1934–2019), politician, economist, diplomat and freedom fighter
Manuel de Novas (born December 24, 1938), composer

Web links

Commons : Santo Antão - collection of images, videos and audio files

Individual evidence

^ ^A ^b Paul Martin Holm et al: Sampling the Cape Verde Mantle Plume: Evolution of Melt Compositions on Santo Antão, Cape Verde Islands. In: Journal of Petrology. Vol. 47, 2006, No. 1, pp. 145-189, doi : 10.1093 / petrology / egi071

^ R. Dietmar Müller, Maria Sdrolias, Caren Gaina, Walter R. Roest: Age, Spreading Rates and Spreading Symmetry of the World's Ocean Crust. In: Geochemistry, Geophysics, Geosystems. ISSN 1525-2027 , Vol. 9 (Q04006), 2008, No. 4, doi : 10.1029 / 2007GC001743 .

^ S. Plesner, Paul Martin Holm, JR Wilson: ⁴⁰ Ar / ³⁹ Ar Geochronology of Santo Antão, Cape Verde Islands. In: Journal of Volcanology and Geothermal Research. ISSN 0377-0273 , Vol. 120, 2002, pp. 103-121.

^ Aeroporto de Santo Antão vai ficar no Porto Novo. ( Memento of the original from September 10, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: ASemana.publ.cv , February 22, 2010; Santo Antão precisa de um novo aeródromo e not de um aeroporto internacional. In: Noticias.sapo.cv , July 27, 2014. @1@ 2

[Holm-1] A ^b Paul Martin Holm et al: Sampling the Cape Verde Mantle Plume: Evolution of Melt Compositions on Santo Antão, Cape Verde Islands. In: Journal of Petrology. Vol. 47, 2006, No. 1, pp. 145-189, doi : 10.1093 / petrology / egi071

[2] R. Dietmar Müller, Maria Sdrolias, Caren Gaina, Walter R. Roest: Age, Spreading Rates and Spreading Symmetry of the World's Ocean Crust. In: Geochemistry, Geophysics, Geosystems. ISSN 1525-2027 , Vol. 9 (Q04006), 2008, No. 4, doi : 10.1029 / 2007GC001743 .

[3] S. Plesner, Paul Martin Holm, JR Wilson: ⁴⁰ Ar / ³⁹ Ar Geochronology of Santo Antão, Cape Verde Islands. In: Journal of Volcanology and Geothermal Research. ISSN 0377-0273 , Vol. 120, 2002, pp. 103-121.