Stratigraphy, structure and geochronology of the Las Cañadas caldera (Tenerife, Canary Islands)

Abstract

After a long period of subaerial fissure-fed extrusions of basaltic magmas (∼ 12 to > 3 Ma) volcanic activity was then concentrated in the central part of Tenerife. Phonolitic magma chambers formed and a central volcanic complex was constructed (the Las Canadas edifice). The formation of a large depression (the Las Canadas caldera) truncated the top of the edifice. The active twin strato-cones Teide—Pico Viejo are sited in this depression. The history of the Las Canadas caldera and edifice are established from stratigraphy, geochronology (K—Ar dates) and volcanological studies. Two different groups are recognized, separated by a major unconformity. The Lower Group is dated at 2 to 3 Ma and includes the products of several volcanic centres, which together represent several cycles. The Upper Group ranges from 1.56 to 0.17 Ma and includes three different formations representing three long-term (∼ 100 to 300 Ka) volcanic cycles. The periods of dormancy between each formation were of ∼ 120 to 250 Ka duration. The Las Canadas caldera is a multicyclic caldera which formed over the period 1.18–0.17 Ma. Each cycle of activity represented by a formation culminated in caldera collapse which affected different sectors of the Las Canadas edifice. Geological observation and geochronology support an origin by collapse into a magma chamber. The minimum volume of pyroclastic ejecta is substantially greater than the present caldera depression volume (45 km3), but approaches the inferred volume of the original caldera depression (> 140 km3). After the formation of the caldera, sector collapses could also occur at the northern flank of the volcano causing the disappearance of the northern side of the caldera wall.

Shallow structure beneath the Central Volcanic Complex of Tenerife from new gravity data: Implications for its evolution and recent reactivation

“…The abundance of high-density bodies in that part of the caldera depression is in perfect agreement with ring fault formation and initiation of the vertical collapse there. The combination of results from these potential field investigations (gravity, magnetotellury and magnetics) provides irrefutable evidence for a vertical collapse origin of the LCC, which is also supported by the abundance of voluminous products of phonolitic explosive (caldera-forming) volcanism on the island (Martí et al, 1994;Edgar et al, 2007;Pittari et al, 2008) It has been suggested by various authors that the head of the Icod valley is buried beneath eruptive products of the PV-PT complex (Martí et al, 1997;Martí et al, 1998;Ablay and Hürlimann, 2000). The horseshoe-shaped alignment of shallow rooted high density bodies to the north of the complex gives the impression of a structural barrier between the complex and the topographic expression of the Icod valley, coinciding with a significant break in slope (Fig.…”

“…The geological and tectonic evolution of the triangular island of Tenerife and the CVC was described in recent papers (Martí et al, 1994;Martí et al, 1998;Araña et al, 2000) and we therefore only provide a short summary. The Canary Islands form a volcanic archipelago with a long-standing history of volcanic activity that began more than 40 million years ago (Araña and Ortíz, 1991).…”

“…Tenerife, the largest of the Canary Islands, has an eruptive history of over 12 million years, including a shield building phase and the construction of a central volcanic structure, the Las Cañadas edifice (LCE) from 3.5 Ma onwards (Martí et al, 1994). Table 1 provides a stratigraphic scheme of the island, and highlights the main constructive and destructive episodes during its formation.…”

“…Martí et al (1994) propose at least three vertical collapses during Upper Group times, which resulted in the formation of the LCC (Table 1).…”

Untitled

“…Son numerosos los estudios dedicados al Edificio Cañadas, que incluyen abundantes dataciones radiométricas (Ancochea et al, 1990(Ancochea et al, , 1999Mitjavila y Villa, 1993;Martí et al, 1994). Sin embargo, los trabajos publicados sobre el Teide y el sistema de rifts, la actividad eruptiva más reciente de la isla, son escasos y apenas incluyen dataciones absolutas, especialmente en el caso del Teide.…”