Causes of complexity in a fallout dominated plinian eruption sequence: 312 ka Fasnia Member, Diego Hernández Formation, Tenerife, Spain

doi:10.1016/j.jvolgeores.2017.07.008

Journal of Volcanology and Geothermal Research

Volume 345, 1 October 2017, Pages 21-45

https://doi.org/10.1016/j.jvolgeores.2017.07.008 Get rights and content

Highlights

•
The 312 ka Fasnia plinian eruption sequence consists of 7 pumice falls, 7 ignimbrites and multiple ash units.
•
Partial intra-plinian collapse occurred multiple times.
•
62 km³ of tephra were erupted, including 49 km³ of juvenile clasts (13 km³ DRE magma), and > 12 km³ of lithic clasts.
•
Two phases of caldera collapse have been inferred.

Abstract

The 312 ka Fasnia eruption from the Las Cañadas Caldera on Tenerife, Canary Islands, Spain, produced a complex sequence of twenty-two intercalated units, including 7 pumice fall, 7 ignimbrite and 8 ash surge and fall deposits that define two distinct eruption sequences (Lower and Upper Fasnia sequences). The fallout units themselves are internally complex, reflecting waxing and waning of the eruption column, while many of the ignimbrites reflect multiple intra-plinian partial column collapse events associated with the injection of lithic clasts into the eruption column. The Lower and Upper Fasnia eruption phases were each terminated by caldera collapse and complete column collapse events. Probable blockage of the conduit and vent system during Lower Fasnia caldera collapse event briefly terminated the eruption, resulting in a short-lived period of erosion and sedimentation prior to the onset of the Upper Fasnia phase. The transition to the Upper Fasnia eruption phase coincided with the eruption of more geochemically homogeneous pyroclasts. In total, 62 km³ of tephra were erupted, including 49 km³ of juvenile clasts and > 12 km³ of lithic clasts. The DRE volume of magma erupted was 13 km³ (Lower Fasnia > 5 km³, Upper Fasnia > 8 km³), two thirds of which (~ 9–10 km³) was deposited purely by fallout. The Fasnia Member is one of the most complex plinian sequences known.

Introduction

Plinian eruption sequences have long been depicted as a progression from an initial, sustained buoyant eruption column phase producing fallout deposits to a column collapse phase producing pyroclastic flows (e.g. Sparks et al., 1973; 0.57 Ma Granadilla Member, Tenerife, Bryan et al., 2000; 184 ka and 172 ka Lower Pumice 1 and 2 eruption sequences, Santorini, Gertisser et al., 2009, Simmons et al., 2016, Simmons et al., 2017a, Simmons et al., 2017b). However, many plinian eruptions are more complex and are characterised by one or more intra-plinian partial collapses of the eruption column, and involving varying degrees of phreatic/phreatomagmatic explosive activity, before a final column collapse. Such sequences are represented by interstratified pumice fallout, intra-plinian ignimbrites, ash layers and, in most cases, a ‘climactic’ ignimbrite which caps the sequence (e.g. 0.28 Ma Poris eruption, Tenerife, Spain, Edgar et al., 2002, Brown and Branney, 2004; 4.5 ka Fogo A, Azores, Pensa et al., 2015; Vesuvius 79 CE, Sigurdsson et al., 1985, Cioni et al., 1992a, Cioni et al., 1999, Gurioli et al., 2005, Shea et al., 2012; 1600 CE Huaynaputina eruption, Peru, Adams et al., 2001, Thouret et al., 2002; the 1912 Novarupta-Katmai eruption, Houghton et al., 2004, Hildreth and Fierstein, 2012; 1991 Pinatubo eruption, Philippines, Rosi et al., 2001). Some plinian sequences are also marked by voluminous lithic clast breccias at the interface of pyroclastic fallout and flow deposits or intercalated within an ignimbrite sequence (e.g., Wright and Walker, 1977, Druitt and Sparks, 1982, Druitt, 1985, Bacon, 1983, Walker, 1985, Allen and Cas, 1998, Rosi et al., 2001, Pittari et al., 2008, Bear et al., 2009, Simmons et al., 2016, Simmons et al., 2017a, Simmons et al., 2017b). Such deposits have been used to infer the onset of caldera collapse (e.g. Bacon, 1983, Edgar et al., 2002, Bear et al., 2009, Simmons et al., 2017a, Simmons et al., 2017b).

The volcanic island of Tenerife preserves many phonolitic plinian eruption sequences, some simple (e.g. Bryan et al., 2000), some complex (e.g. Edgar et al., 2002). In this paper, we focus on the most complex and voluminous, the 312 ka Fasnia Member eruption sequence. We present the detailed stratigraphy based on island-wide mapping and correlation, we estimate the volume for each major depositional unit, assess the timing of ignimbrite formation, and discuss the numerous factors that determined eruption processes. This study will enhance understanding of the hazards of complex plinian eruptions on Tenerife and elsewhere.

Section snippets

Geological background

Tenerife is the largest of the Canary Islands, Spain. It emerged as an alkali basaltic shield volcano system ca.12 Myr ago (Ancochea et al., 1990; Table 1), producing thick, mostly mafic lava sequences that are now exposed in three heavily dissected massifs (the ‘Old Basaltic Series’ of Fuster et al., 1968; Fig. 1a, Table 1). After 3.8 Ma, a central post-shield stratovolcanic complex, the Las Cañadas Edifice, developed in the centre of the island (Fig. 1a). An extended phase of mafic to felsic

Terminology

Although the umbrella term “pyroclastic density current” (PDC) has been in vogue in recent years for gravity driven hot flows of pyroclastic debris, this term is too non-specific when detailed process interpretation is required of particular deposits. It does not adequately distinguish between the different types of pyroclastic density currents, such as the spectrum of high particle concentration pyroclastic flows (pumice and ash, scoria and ash, block and ash and blast flows) and surges (base

Stratigraphy and facies of the Fasnia Member

The 312 ka Fasnia Member is one of the most widespread units on Tenerife, having originally covered > 80% of the island. It has been subdivided into 22 stratigraphic units based on grain size, sorting, componentry, depositional structures, deposit morphology and regional correlations (Fig. 2, Fig. 3). The main lithofacies are first described and their origins interpreted, and then individual stratigraphic units are discussed and interpreted within the newly established stratigraphy of the Fasnia

Complexity of the Fasnia eruption sequence and eruption column instability

The Fasnia eruption sequence, with 7 main magmatic plinian fallout units, interspersed with 7 main ignimbrite units, and 8 main ash horizons, seems to be at least as complex as other examples listed in the introduction. The complexities reflect partial to total eruption column collapse events, and at least some phreatic/phreatomagmatic/hydrothermal influences. Apart from after the major Ravelo and Atogo Ignimbrite-forming events, there is no evidence to suggest that the eruption column

Conclusions

• The Fasnia eruption sequence is one of the most complex plinian eruption sequences yet recorded, with multiple plinian pumice fallout deposits, which themselves are often internally complex, at least 7 ignimbrites, and multiple ash horizons of both surge and fallout origin.

• The complexity in the eruption sequence reflects an unstable eruption column that was susceptible to numerous, partial, eruption column collapse events generating intra-plinian ignimbrites and surges.

• Much of the

Acknowledgements

Much of this research represents part of the PhD research of Campbell Edgar at Monash University. The research was funded by discretionary research funds of Ray Cas, NSF grant EAR-0001013 to John Wolff, and MCyT REN2001-0502/RIES and EC EVG1-CT-2002-00058 grants to Joan Marti. We thank Peter Larson, Jeff Grandy, Inés Galindo, Nemesio Pérez, Jill Middleton, Keith Brunstad and Janet Sumner for assistance in the field and discussion on aspects of Tenerife geology, and Jesus Garrido and the staff

References (87)

E. Ancochea et al.
Volcanic evolution of the island of Tenerife (Canary Islands) in the light of new K-Ar data
J. Volcanol. Geotherm. Res.
(1990)
E. Ancochea et al.
Evolution of the Canadas edifice and its implications for the origin of the Canadas Caldera (Tenerife, Canary Islands)
J. Volcanol. Geotherm. Res.
(1999)
J. Andújar et al.
Experimental constraints on pre-eruptive conditions of phonolitic magma from the caldera-forming El Abrigo eruption, Tenerife (Canary Islands)
Chem. Geol.
(2008)
C.R. Bacon
Eruptive history of Mount Mazama and Crater Lake caldera, Cascade range, U.S.A
J. Volcanol. Geotherm. Res.
(1983)
A.N. Bear et al.
The implications of spatter, pumice and lithic clast rich proximal co-ignimbrite lag breccias on the dynamics of caldera forming eruptions: the 151 ka Sutri eruption, Vico Volcano, Central Italy
J. Volcanol. Geotherm. Res.
(2009)
S.E. Bryan et al.
Lithic breccias in intermediate volume phonolitic ignimbrites, Tenerife (Canary Islands): constraints on pyroclastic flow depositional processes
J. Volcanol. Geotherm. Res.
(1998)
S.E. Bryan et al.
The 0.57 Ma plinian eruption of the Granadilla Member, Tenerife (Canary Islands): an example of complexity in eruption dynamics and evolution
J. Volcanol. Geotherm. Res.
(2000)
S. Carey et al.
The intensity and magnitude of Holocene plinian eruptions from Mount St. Helens volcano
J. Volcanol. Geotherm. Res.
(1995)
R. Cioni et al.
Morphologic features of juvenile pyroclasts from magmatic and phreatomagmatic deposits of Vesuvius
J. Volcanol. Geotherm. Res.
(1992)
T.H. Druitt et al.
Lithic breccia and ignimbrite erupted during the collapse of Crater Lake Caldera, Oregon
J. Volcanol. Geotherm. Res.
(1986)

B.F. Houghton et al.

(2015)

A. Pittari et al.

The influence of palaeotopography on facies architecture and pyroclastic flow processes of a lithic-rich ignimbrite in a high gradient setting: the Abrigo Ignimbrite, Tenerife, Canary Islands

J. Volcanol. Geotherm. Res.

(2006)

A. Pittari et al.

The Granadilla pumice deposit of southern Tenerife, Canary Islands

Proc. Geol. Assoc.

(1973)

M.J. Branney et al.

Pyroclastic Density Currents and the Sedimentation of Ignimbrites

(2002)

R.J. Brown et al.

The Quaternary pyroclastic succession of southeast Tenerife, Canary Islands: explosive eruptions, related caldera subsidence, and sector collapse

Geol. Mag.

(2003)

Cited by (15)

Alternating Subplinian and phreatomagmatic phases during the construction of a phonolitic maar-diatreme volcano (Caldera del Rey, Tenerife, Canary Islands)
2023, Journal of Volcanology and Geothermal Research
The Early Pleistocene, well exposed, Caldera del Rey maar-diatreme volcano, Tenerife, Canary Islands was constructed during a ∼ VEI 4 phonolitic eruption that involved two cycles of magmatic-to-phreatomagmatic activity and resulted in two overlapping craters aligned NE-SW. Magmatic phases fed unsteady Subplinian eruption columns that reached 8–12 km altitude and dispersed tephra to the west and southwest of the volcano and shed pyroclastic density currents. Phreatomagmatic phases, driven by explosive interactions between magma and groundwater, constructed an extensive tephra ring via deposition from ballistic curtains, pyroclastic density currents, and tephra fall. Near-optimal-scaled depth phreatomagmatic explosions (strong and/or shallow) excavated a substantial diatreme beneath the north crater and constructed a substantial tephra ring. This abruptly transitioned to deeper-than-optimal scaled depth explosions (weak and/or deep) that erupted mostly fine ash which was dispersed by dilute pyroclastic density currents and fallout and filled the south crater. At distances of >4 km from the volcano, over a metre of ash and pumice accumulated during the phreatomagmatic phases. The Caldera del Rey volcano provides an instructive study on how interaction between ascending felsic magma and groundwater can modify Subplinian eruptions.
The upper Pleistocene (1.8–0.7 Ma) explosive eruptive history of Las Cañadas, ocean-island volcano, Tenerife
2023, Journal of Volcanology and Geothermal Research
While most ocean-island volcanism is effusive, recent evidence has demonstrated that intraplate ocean island volcanoes can exhibit protracted explosive histories, with catastrophic eruption styles and hazardous behaviour more typically associated with volcanoes in continental and plate-margin settings. Tenerife is the largest explosive ocean-island volcano on Earth, with a prolonged (∼2 Ma) post-erosional history of caldera-forming, plinian and ignimbrite eruptions of evolved composition. The 0.7–1.8 Ma succession with 20 newly defined formations is reported for southern Tenerife, Canary Islands. In the last 2 Myr, the Las Cañadas volcano has produced >42 pumice-fall eruptions, 21 with extensive ignimbrites, and 12 inferred caldera collapse events. Pyroclastic density currents have repeatedly travelled more than15 km from source to the ocean, filling valleys and burying extensive interfluves. A robust whole-rock chemistry dataset, selected mineral chemistry, coupled with new ⁴⁰Ar/³⁹Ar ages of units through the pyroclastic stratigraphy, allow recognition of magmatic trends within the system on the order of 100 ky. The catastrophic explosive eruptions form three, 0.2–0.5 Myr-duration clusters (the Ucanca, Guajara and Diego-Hernandez) that do not appear to correspond simply with geochemical cycles, or to cycles of increasing eruption size or explosivity as has been previously proposed. During the clusters, large eruption frequencies averaged 1 every 20–45 kyrs. The eruption clusters were separated by hiatuses of ∼240–260 kyr, recorded by soils and unconformities, and may reflect marked changes in geographic dispersals following giant landslide breaches in Las Cañadas caldera wall. Two concurrent evolutionary magmatic trends are distinguished: one producing crystal-rich magmas, the other formed the cooler crystal-poor magmas: both spanned over a million years until 0.66 Ma, when the former ceased.
Tenerife, a complex end member of basaltic oceanic island volcanoes, with explosive polygenetic phonolitic calderas, and phonolitic-basaltic stratovolcanoes
2022, Earth-Science Reviews
Citation Excerpt :
In the Diego Hernandez Formation (Table 5), ignimbrite DRE magma volumes range from 0.2 to 3.7 km3, but the climactic Abrigo ignimbrite has a minimum DRE magma volume of 5 km3, but it could be as large as 20 km3 DRE (Table 5). Many Tenerife ignimbrites have a very high lithic clast content (5–60%; Fig. 17c-f; e.g. Pittari et al., 2008; Edgar et al., 2007, 2017), with lithic clast content also varying in different facies within individual ignimbrites. Many of the lithic clasts are hydrothermally altered phonolite and basalt clasts, as well as a significant volume of deeper seated syenite clasts, which were clearly sub-surface derived.
Tenerife, one of the active oceanic island volcanoes in the Canary Islands, located in the eastern Atlantic Ocean off northwest Africa, is the second largest intraplate oceanic island volcanic system after Hawai'i but is more complex and represents a different and more evolved end-member to Hawai'i in the spectrum of oceanic island volcanic systems. Tenerife began life as a mafic oceanic shield volcano at ~12 Ma, erupting (picro)basalt, basanite, hawaiite, mugearite, benmoreite series lavas of the Older Basaltic Series. These were derived from a spatially variable mantle plume source with varying degrees of magma-lithosphere interaction and fractional crystallisation. At ~3.05 Ma an evolved phonolitic magma system began to develop under the centre of the island. That led to the building of an initial summit effusive and explosive stratovolcano system (the Las Cañadas edifice) represented by the poorly understood Lower Group, followed by development of 3 cycles of explosive phonolitic caldera forming activity (Ucanca, Guajara, Diego Hernández) of the Upper Group, from ~1.66 Ma to ~0.175 Ma, each cycle separated by ~180 kyr (the recharge interval?). Phonolite genesis is complex, involving fractional crystallisation, partial melting of island crust including syenitic plutons, and recycling of crystal mushes. Three coalesced explosive calderas are preserved at the summit of Tenerife, constituting the Las Cañadas Caldera Complex. Since ~0.175 Ma two stratovolcanoes (Teide, Pico Viejo) have been growing along the northern rim of the caldera complex, becoming more phonolitic from basaltic beginnings and more explosive, perhaps heralding the beginning of a new explosive cycle. Simultaneously shield building basaltic volcanism has continued on the flanks to historic times through multiple monogenetic eruptions along the linear northwestern and northeastern rift zones, and a more diffuse southern volcanic zone. Volcanic eruption styles have included fissure fed basaltic shield sheet lava eruptions, monogenetic basaltic cone lava and scoria eruptions, highly explosive plinian phonolitic pumice and ash fallout, and pyroclastic flow forming eruptions. The volumes of the largest explosive eruptions likely caused a component of magma chamber roof block subsidence, with multiple, spaced eruptions during each caldera forming cycle producing incremental caldera collapse and polygenetic calderas. Major landslides coincide with some of the large explosive eruptions, raising the question of cause and effect.
Multiple related flank collapses on volcanic oceanic islands: Evidence from the debris avalanche deposits in the Orotava Valley water galleries (Tenerife, Canary Islands)
2020, Journal of Volcanology and Geothermal Research
Citation Excerpt :
The main centre of the edifice was situated by these authors according to a number of felsic dykes that cut Las Pilas and older formations. That position roughly corresponds to the main source area of the felsic pyroclastic units of the Diego Hernández Formation dated at <370–170 ka, which also belongs to the Cañadas III Edifice, but are younger than the WOLs (Edgar et al., 2007, 2017). The main centre of Cañadas III at the time of both failures must have been in a similar position, more or less central between the Tigaiga massif, where lava have a northward dip, and Las Pilas, where they dip to the southeast (Fig. 9).
Catastrophic flank collapses are common on oceanic islands of volcanic origin and often recognizable from the resulting morphology as large U-shaped embayments. However, post-collapse volcanic activity can infill such features, thereby obscuring them. This study takes advantage of a dense network of long sub-horizontal galleries for groundwater extraction in the flank collapse structure of the Orotava Valley (Tenerife, Canary Islands). This impressive landform is located in the overlapping zone of the NE Rift and the Cañadas Edifice of this volcanic island. Three debris avalanche deposits (DADs) have been identified inside the waterworks bored into the valley's western sector. The deeper layer, the Lower-DAD (L-DAD) was previously described under the local name of mortalón. This deposit lies unconformably over older volcanic rocks, where a prominent shear-zone is developed, here interpreted as the detachment plane of a massive rockslide. The L-DAD was therefore produced during the large failure event, the Orotava Landslide (OL), which carved the depression. Two younger DADs, much smaller in volume and not previously described, were also identified in the underground strata: the Intermediate- (I-DAD) and Upper-DAD (U-DAD). Both correlate well with the thick breccia deposits cropping out at the base of the marine cliff along the western coast of the valley. The I-DAD and U-DAD are conformably intercalated between the lava flows and other volcanics infilling the depression, and their bases are erosive/depositional features without structural deformation zones below them. Their stratigraphic setting and geometrical reconstruction indicate that both deposits were emplaced after the valley was formed by the OL event, in two successive failures here called Western Orotava Landslides (WOLs). The younger, called WOL-2, was dated at 494 ± 22 ka using the ⁴⁰Ar/³⁹Ar method. These two subaerial failures affected the upper eastern flank of the Cañadas III Edifice, previously destabilized when the OL failure event carved a steep wall at its foot, the western lateral escarpment of the Orotava Valley.
Controls of magma chamber zonation on eruption dynamics and deposits stratigraphy: The case of El Palomar fallout succession (Tenerife, Canary Islands)
2020, Journal of Volcanology and Geothermal Research
Anticipating volcanic eruptions at central volcanoes require knowing how magma chambers prepare for new eruptions. Pre-eruptive processes that occur in such magma chambers are recorded in the products of these eruptions, so their characterisation in terms of magma composition and physics offers the clues to understand past eruptions and predict future ones. Here, we study the very well preserved pyroclastic succession of El Palomar Member (712 ± 41 ka), in Las Cañadas caldera, Teide, Canary Islands. This deposit resulted from a single explosive eruption of a phonolitic magma that started with a sustained eruption column (sub-plinian or plinian) that formed a massive, 40 m thick non-welded fallout deposit, progressively changing into a lower intensity fire fountain that deposited a 25 m thick fallout succession of non-welded to strongly welded pumices. Stratigraphic and petrological data suggest that this eruption was related to a thermally-compositionally zoned and relatively shallow magma chamber in which the arrival of a hotter and more mafic magma rapidly triggered the eruption. The studied deposit shows how this zoned structure was maintained during the whole process, which allows one to reconstruct what happened during the eruption. Comparison of this eruption with the current situation at Teide volcano alerts on the potential rapid preparation for new eruptions in the case that sufficient phonolitic magma was available in the shallow plumbing system of this active volcano if new inputs of deeper magma take place.
Las Cañadas caldera, Tenerife, Canary Islands: A review, or the end of a long volcanological controversy
2019, Earth-Science Reviews
The Las Cañadas caldera is one of the best exposed volcanic calderas in the world and one of the few known evolved alkaline volcanoes. It truncates the pre-Teide-Pico Viejo central volcanic edifice, the Las Cañadas edifice, which started to take shape at the end of the formation of a large basaltic shield that forms the main part of island of Tenerife. Historically, the origin of the Las Cañadas caldera has been controversial, as it has been interpreted as the result of either multiple vertical collapses or due to a giant sector collapse. The available stratigraphical, structural, volcanological, geochronological, and geophysical data, as well as its comparison to other well-known collapse calderas should not offer any doubt as to its direct relationship with a long history of phonolitic explosive volcanism. However, the existence of large landslide events on Tenerife, which have significantly modified the flanks of the Las Cañadas volcano, have also been used as a potential explanation for the origin of the Las Cañadas depression. This contribution reviews the available information on the Las Cañadas caldera, the causes of this controversy, and rationalises the most plausible explanation for the origin of Las Cañadas caldera based on the current evidence gathered from all previous studies.

View all citing articles on Scopus

View full text

Causes of complexity in a fallout dominated plinian eruption sequence: 312 ka Fasnia Member, Diego Hernández Formation, Tenerife, Spain

Highlights

Abstract

Introduction

Section snippets

Geological background

Terminology

Stratigraphy and facies of the Fasnia Member

Complexity of the Fasnia eruption sequence and eruption column instability

Conclusions

Acknowledgements

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

Chem. Geol.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

Developments in Volcanology

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

Lithos

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

The physical volcanology of the 1600 eruption of Huaynaputina, southern Peru

Bull. Volcanol.

Lateral variations within coarse co-ignimbrite lithic breccias of the Kos Plateau Tuff, Greece

Bull. Volcanol.

Rhyolitic phreatomagmatism explored: Tepexitl tuff ring (eastern Mexican Volcanic Belt)

J. Volcanol. Geotherm. Res.

Textural and geochemical constraints on eruptive style of the 79 AD eruption at Vesuvius

Bull. Volcanol.

Determination of the largest clast sizes of tephra deposits for the characterization of explosive eruptions: a study of the IAVCEI commission on tephra hazard modelling

Bull. Volcanol.

Estimating the volume of tephra deposits: a new simple strategy

Geology

Plume height, volume, and classification of explosive volcanic eruptions based on the Weibull function

Bull. Volcanol.

Tephra fallout in the eruption of Soufriere Hills Volcano, Montserrat

The Granadilla pumice deposit of southern Tenerife, Canary Islands

Proc. Geol. Assoc.

Pyroclastic Density Currents and the Sedimentation of Ignimbrites

The Quaternary pyroclastic succession of southeast Tenerife, Canary Islands: explosive eruptions, related caldera subsidence, and sector collapse

Geol. Mag.