The geology of the Canary Islands is dominated by volcanoes and volcanic rock. The Canary Islands are a group of volcanic islands in the North Atlantic Ocean, near the coast of Northwest Africa. Geologically, the main islands are Lanzarote, Fuerteventura, Gran Canaria, Tenerife, La Gomera, La Palma, and El Hierro. There are also some minor islands and islets. The Canary Islands are on the African tectonic plate but they are far from the plate's edges; the islands are therefore an example of intraplate volcanism.
The Canary Islands, and some associated underwater volcanic mountains on the ocean floor, are in the Canary Volcanic Province. The current long period of volcanic activity in this province started about 70 million years ago. For many millions of years, all the volcanic eruptions in the province occurred on the ocean floor. In the last 20.2 million years, enough lava has accumulated at several of the underwater volcanic mountains to build them above sea level, forming the Canary Islands. The eastern islands emerged first, followed by each of the more westerly islands, in turn.
Volcanic activity has occurred during the Holocene Epoch (the last 11,700 years) on all of the main islands except La Gomera. The Canary Islands region is still volcanically active. The most recent volcanic eruption on land occurred in 2021 and the most recent underwater eruption was in 2011–2012.
Islands
The Canary Islands are a , east–west aligned archipelago of volcanic islands in the eastern part of the North Atlantic Ocean, off the coast of Northwest Africa. Geologically, there are seven main islands in the Canary Islands; from east to west they are Lanzarote, Fuerteventura, Gran Canaria, Tenerife, La Gomera, La Palma, and El Hierro.
Close to the coasts of the main islands, there are some minor islands and named islets including: near Lanzarote: the Chinijo Archipelago (La Graciosa, Alegranza, Montaña Clara, Roque del Este, and Roque del Oeste); near Fuerteventura: Lobos; near Tenerife: Roques de Anaga, Roque de Garachico; near Gran Canaria: Roque Melenara; near La Gomera: El Roquillo; near La Palma: Roque de Santo Domingo, Roque de las Tabaidas, Roque del Guincho; near El Hierro: Roques de Salmor;
There are also numerous unnamed islets.
The seven main Canary Islands originated as separate submarine seamount volcanoes on the ocean floor, which is deep in the Canarian region.
Lanzarote and Fuerteventura are separated by an , ocean strait. Both islands are parts of a volcanic ridge called the Canary Ridge. These two islands have sometimes been a single island in the past when worldwide sea level was lower than its present level, for example during the Last Glacial Maximum about 20,000 years ago. The single island is sometimes referred to as Mahan.
The volume of volcanic rock that has built up the Canary Islands to thousands of metres above the ocean floor is about ; 96% of this lava is hidden below sea level and 4% () is above sea level. The western islands have more of their volume (7%) above sea level than do the eastern islands (2%).
Regional setting
The Canary Islands are built upon one of the oldest regions of Earth's oceanic crust (175–150 Ma), part of the slow-moving African plate, in the continental rise section of Northwest Africa's passive continental margin.
The rocks under and in the Canary Islands are a record of multiple periods of volcanic activity:
Starting about 180 Ma (million years ago), the oceanic crust of the North Atlantic Ocean was formed; it consists of igneous rocks (plutonic rocks overlain by volcanic rocks) that were gradually covered by layers of sedimentary rocks. The igneous part of the oceanic crust was formed by seafloor spreading at the divergent plate boundary between the North American and African plates, as a result of the breakup of the supercontinent Pangaea; in the Canary Islands region, this occurred in the Jurassic Period. North America and Northwest Africa separated while the Atlantic Ocean grew between them. Although this volcanic activity formed the ocean floor on which the Canary Islands were later formed, this seafloor spreading type of volcanic activity was not involved in the formation of the islands. Starting about 70 Ma, volcanic activity in the Canary Volcanic Province has occurred at numerous seamounts across the region now occupied by the Canary Islands as well as an area of the ocean floor up to north of the Canary Islands. The northernmost of this group of seamounts, Lars seamount (about north of Lanzarote), has been dated to 68 Ma. The seamounts are progressively younger southwestwards towards Lanzarote. Some seamounts developed into islands: first to emerge above sea level, at about 30 to 25 Ma, were the Selvagen Islands ( north of where the Canary Islands would later form). Then, each of the Canary Islands emerged as an island between 20.2 Ma and 1.1 Ma. Volcanic activity in the Canary Volcanic Province has continued to the present day.
Island development stages
The geological features of the Canary Islands place this island group at one end of a spectrum of types of intraplate volcanic oceanic islands that form in deep parts of the oceans, far from tectonic plate boundaries; the Hawaiian Islands are at the other end of this spectrum.
Intraplate volcanic oceanic islands follow a sequence of development stages. The sequence of stages was originally recognised, during the 1930s and 1940s, in the Hawaiian Islands, where eight stages were defined. In the Hawaiian volcanic island chain and some other volcanic island chains, some of the later stages occur due to subsidence of the island as seafloor spreading moves the island away from the focus of volcanic activity. In contrast, the Canary Islands have not undergone significant subsidence; therefore the sequence has been adapted in the Canary Islands to the following stages: submarine (seamount) stage (El Hijo de Tenerife seamount) shield-building stage (La Palma, El Hierro) erosional stage (La Gomera) post-erosional (or rejuvenation) stage (Tenerife, Gran Canaria, Lanzarote, Fuerteventura)
The Canary Islands differ from some other volcanic oceanic islands, such as the Hawaiian Islands: for example, the Canary Islands have stratovolcanoes, compression structures and a lack of significant subsidence.
The seven main Canary Islands originated as separate submarine seamount volcanoes on the floor of the Atlantic Ocean (although Tenerife and La Gomera are close enough to each other for their seamounts to overlap as they grew; the distance between Lanzarote and Fuerteventura was also small enough for some of their shield volcanoes to overlap as they grew, forming a single volcanic ridge). Each seamount, built up by the eruption of many lava flows, eventually became an island. Subaerial volcanic eruptions continued on each island.
The stage of development of each island is shown in its current topography. The five younger islands, in the western and central sections of the island group, are higher and more rugged. The two oldest, eastern islands of Fuerteventura and Lanzarote, where fissure eruptions have dominated in the rejuvenation stage, have more subdued topography with heights below .
Age From about 70 Ma to 20.2 Ma, all the volcanic activity in the Canary Islands region occurred as underwater eruptions and the islands did not yet exist. Eventually, enough lava accumulated at particular locations to form each island of the Canary Islands archipelago. The age of the first underwater eruptions differs from island to island; for example, the first underwater eruptions at La Gomera were at more than 12 Ma but at La Palma they were at 4 Ma. Seamount stage rocks are not exposed on Lanzarote, Tenerife, Gran Canaria and El Hierro, which has hindered dating of the earliest underwater volcanic activity at these islands.
The age of the oldest subaerially-erupted lavas on each island decreases from east to west along the island chain: Lanzarote-Fuerteventura (20.2 Ma), Gran Canaria (14.6 Ma), Tenerife (11.9 Ma), La Gomera (9.4 Ma), La Palma (1.7 Ma) and El Hierro (1.1 Ma).
The age of the youngest sedimentary rocks under each of the islands also decreases from east to west along the island chain, showing that the east-to-west age progression also applies to the start of seamount formation on the ocean floor.
Geological map
Translation of Spanish text in the map:
Geología de las islas Canarias = Geology of the Canary Islands Volcanismo = Volcanism Océano Atlántico = Atlantic Ocean Erupciones históricas = Historical eruptions Volcanismo reciente = Recent volcanism Volcanismo plioceno-pleistoceno = Pliocene-Pleistocene volcanism Volcanismo mioceno = Miocene volcanism Formaciones intrusivas = Intrusive formations Complejo basal = Basal complex Formaciones sedimentarias = Sedimentary formations Conos volcánicos = Volcanic cones Calderas y estructuras calderiformes = Calderas and calderiform structures Nota: La erupción de El Hierro ocurrida en octubre de 2011, se considera histórica como cualquier erupción en la que hay documento escrito sobre su ocurrencia = Note: The eruption of El Hierro that occurred in October 2011 is considered historical, as is any eruption of which there is a written document about its occurrence Fuente = Source Actualización erupción de El Hierro = El Hierro eruption update
Rock types Igneous rocks
In the Canary Islands, igneous rocks of the alkaline magma series are common, while rocks of the sub-alkaline tholeiitic magma series are rare.
Volcanic rock types found on the Canary Islands are typical of oceanic islands. The volcanic rocks include alkali basalts, basanites, phonolites, trachytes, nephelinites, trachyandesites, tephrites and rhyolites. There are lava flows as well as deposits of pyroclastic material, such as tuff (made of volcanic ash or lapilli).
Outcrops of plutonic rocks (for example, syenites, gabbros and pyroxenites) that formed deep below the surface occur on Fuerteventura, La Gomera and La Palma.
Apart from some islands of Cape Verde (another volcanic island group in the Atlantic Ocean, about south-west of the Canary Islands), Fuerteventura is the only oceanic island known to have outcrops of carbonatite. On Fuerteventura, the carbonatite occurs as igneous intrusions.
Sedimentary rocks Minor deposits of sedimentary rocks outcrop on the Canary Islands. They consist of calcrete/caliche, sandstone, conglomerate, aeolianite, and limestone.
Metamorphic rocks Some metamorphic rocks are exposed on the Canary Islands.
The structurally deepest parts (the basal complexes) of Fuerteventura, La Gomera, and La Palma include hydrothermally metamorphosed oceanic crust rocks and lower seamount rocks that were altered from their original igneous and sedimentary rock types and folded before the three islands emerged. These rocks were subjected to pressures and temperatures corresponding to zeolite, prehnite-pumpellyite and greenschist facies. These metamorphic rocks have been uplifted and then exposed by erosion of younger overlying rocks.
There are small amounts of migmatite and hornfels that outcrop in contact aureoles bordering igneous intrusions in the Basal Complex of Fuerteventura.
Some sedimentary rocks of the uppermost oceanic crust under Lanzarote were thermally metamorphosed by heat from intrusion of magma into the sedimentary rocks. The original sandstones and shales were transformed into quartzite and slate respectively. Later volcanic eruptions have transported fragments of these quartzites and slates onto the island's surface as xenoliths within basaltic lava.
Origins of volcanism
Several hypotheses have been proposed to explain the volcanism of the Canary Islands. Two hypotheses have received the most attention from geologists:
The volcanism is related to crustal fractures extending from the Atlas Mountains of Morocco.