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Pedroza, Kirsten
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Publications (7 of 7) Show all publications
Zaczek, K., Troll, V., Cachao, M., Ferreira, J., Deegan, F., Carracedo, J.-C., . . . Burchardt, S. (2015). Nannofossils in 2011 El Hierro eruptive products reinstate plume model for Canary Islands. Scientific Reports, 5, 7945
Open this publication in new window or tab >>Nannofossils in 2011 El Hierro eruptive products reinstate plume model for Canary Islands
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2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, p. 7945-Article in journal (Refereed) Published
Abstract [en]

The origin and life cycle of ocean islands have been debated since the early days of Geology. In the case of the Canary archipelago, its proximity to the Atlas orogen led to initial fracture-controlled models for island genesis, while later workers cited a Miocene-Quaternary east-west age-progression to support an underlying mantle-plume. The recent discovery of submarine Cretaceous volcanic rocks near the westernmost island of El Hierro now questions this systematic age-progression within the archipelago. If a mantle-plume is indeed responsible for the Canaries, the onshore volcanic age-progression should be complemented by progressively younger pre-island sedimentary strata towards the west, however, direct age constraints for the westernmost pre-island sediments are lacking. Here we report on new age data obtained from calcareous nannofossils in sedimentary xenoliths erupted during the 2011 El Hierro events, which date the sub-island sedimentary rocks to between late Cretaceous and Pliocene in age. This age-range includes substantially younger pre-volcanic sedimentary rocks than the Jurassic to Miocene strata known from the older eastern islands and now reinstate the mantle-plume hypothesis as the most plausible explanation for Canary volcanism. The recently discovered Cretaceous submarine volcanic rocks in the region are, in turn, part of an older, fracture-related tectonic episode.

National Category
Geology
Research subject
Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
Identifiers
urn:nbn:se:uu:diva-241060 (URN)10.1038/srep07945 (DOI)000348164600002 ()25609055 (PubMedID)
Available from: 2015-01-08 Created: 2015-01-08 Last updated: 2017-12-05Bibliographically approved
Troll, V., Deegan, F., Burchardt, S., Zaczek, K., Carracedo, J.-C., Meade, F. C., . . . Barker, A. (2015). Nannofossils: the smoking gun for the Canarian hotspot. Geology Today, 31(4), 137-145
Open this publication in new window or tab >>Nannofossils: the smoking gun for the Canarian hotspot
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2015 (English)In: Geology Today, ISSN 0266-6979, E-ISSN 1365-2451, Vol. 31, no 4, p. 137-145Article in journal (Refereed) Published
Abstract [en]

The origin of volcanism in the Canary Islands has been a matter of controversy for several decades. Discussions have hinged on whether the Canaries owe their origin to seafloor fractures associated with the Atlas Mountain range or to an underlying plume or hotspot of superheated mantle material. However, the debate has recently come to a conclusion following the discovery of nannofossils preserved in the products of the 2011–2012 submarine eruption at El Hierro, which tell us about the age and growth history of the western-most island of the archipelago. Light coloured, pumice-like ‘floating rocks’ were found on the sea surface during the first days of the eruption and have been shown to contain fragments of pre-island sedimentary strata. These sedimentary rock fragments were picked up by ascending magma and transported to the surface during the eruption, and remarkably retained specimens of pre-island Upper Cretaceous to Pliocene calcareous nannofossils (e.g. coccolithophores). These marine microorganisms are well known biostratigraphical markers and now provide crucial evidence that the westernmost and youngest island in the Canaries is underlain by the youngest sediment relative to the other islands in the archipelago. This finding supports an age progression for the onset of volcanism at the individual islands of the archipeligo. Importantly, as fracture-related volcanism is known to produce non-systematic age-distributions within volcanic alignments, the now-confirmed age progression corroberates to the relative motion of the African plate over an underlying mantle plume or hotspot as the cause for the present-day Canary volcanism.

National Category
Geology Geosciences, Multidisciplinary
Research subject
Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
Identifiers
urn:nbn:se:uu:diva-270973 (URN)DOI: 10.1111/gto.12100 (DOI)
Available from: 2016-01-05 Created: 2016-01-05 Last updated: 2017-12-01
Carracedo, J. C., Troll, V., Zaczek, K., Rodriguez-Gonzales, A., Soler, V. & Deegan, F. (2015). The 2011-2012 submarine eruption off El Hierro, Canary Islands: New lessons in oceanic island growth and volcanic crisis management. Earth-Science Reviews, 150, 168-200
Open this publication in new window or tab >>The 2011-2012 submarine eruption off El Hierro, Canary Islands: New lessons in oceanic island growth and volcanic crisis management
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2015 (English)In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 150, p. 168-200Article in journal (Refereed) Published
Abstract [en]

Forty years after the eruption of the Teneguía volcano on La Palma, 1971, the last volcanic event in the Canary Islands, a submarine eruption took place in 2011 off-shore El Hierro, the smallest and youngest island of the archipelago. In this paper, we review the periods of seismic unrest leading up to the 2011–2012 El Hierro eruption, the timeline of eruptive events, the erupted products, the wider societal impacts, and the insights garnered for our understanding of ocean island growth mechanisms and hazard management. Seismic precursors allowed early detection of magmatic activity and prediction of the approximate location of the eruption. White coloured “floating stones” (“xeno-pumice”) were described within the first few days of the events, the origin of which were hotly debated because of their potential implications for the character of the eruption. Due to epistemic uncertainty derived from delayed flow of scientific information and equivocal interpretations of the “floating stones”, the El Hierro 2011–2012 events were characterised by cautious civil protection measures, which greatly impacted on the residents' lives and on the island's economy. We therefore summarise the scientific lessons learned from this most recent Canary Island eruption and discuss how emergency managers might cope with similar situations of uncertainty during future eruptive events in the region.

Keywords
El Hierro; Submarine eruption; Ocean islands; Magmatic underplating; Island growth and evolution; Volcanic crisis management
National Category
Geology
Research subject
Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
Identifiers
urn:nbn:se:uu:diva-241062 (URN)10.1016/j.earscirev.2015.06.007 (DOI)000364796200010 ()
Funder
The Royal Swedish Academy of SciencesSwedish Research Council, 2013-5628
Available from: 2015-01-08 Created: 2015-01-08 Last updated: 2017-12-05Bibliographically approved
Pedroza, K., Troll, V., Cachao, M., Ferreira, J., Carracedo, J. C., Soler, V., . . . Burchardt, S. (2014). Canary Island volcanism: fracture induced or mantle plume related?. In: : . Paper presented at Cities on Volcanoes.
Open this publication in new window or tab >>Canary Island volcanism: fracture induced or mantle plume related?
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2014 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Geology
Research subject
Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
Identifiers
urn:nbn:se:uu:diva-241057 (URN)
Conference
Cities on Volcanoes
Available from: 2015-01-08 Created: 2015-01-08 Last updated: 2015-01-08
Pedroza, K., Troll, V., Deegan, F., Meade, F. C., Burchardt, S., Carracedo, J., . . . Barker, A. (2014). Origin and significance of the 2011 El Hierro xeno-pumice. In: : . Paper presented at EGU General Assembly, 2014, Vienna.
Open this publication in new window or tab >>Origin and significance of the 2011 El Hierro xeno-pumice
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2014 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Geology Geosciences, Multidisciplinary
Research subject
Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
Identifiers
urn:nbn:se:uu:diva-240939 (URN)
Conference
EGU General Assembly, 2014, Vienna
Available from: 2015-01-08 Created: 2015-01-08 Last updated: 2015-01-08
Pedroza, K., Troll, V., Deegan, F., Meade, F. C., Klügel, A., Burchardt, S., . . . Barker, A. (2014). Significance of 2011/201 El Hierro xeno-pumice. In: : . Paper presented at Cities of Volcanoes.
Open this publication in new window or tab >>Significance of 2011/201 El Hierro xeno-pumice
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2014 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Geology
Research subject
Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
Identifiers
urn:nbn:se:uu:diva-241053 (URN)
Conference
Cities of Volcanoes
Available from: 2015-01-08 Created: 2015-01-08 Last updated: 2015-01-08
Troll, V., Klügel, A., Longpré, M.-A., Burchardt, S., Deegan, F., Carracedo, J., . . . Pedroza, K. (2012). Floating stones off El Hierro, Canary Islands: xenoliths of pre-island sedimentary origin in the early products of the October 2011 eruption. Solid Earth, 3(1), 97-110
Open this publication in new window or tab >>Floating stones off El Hierro, Canary Islands: xenoliths of pre-island sedimentary origin in the early products of the October 2011 eruption
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2012 (English)In: Solid Earth, ISSN 1869-9510, E-ISSN 1869-9529, Vol. 3, no 1, p. 97-110Article in journal (Refereed) Published
Abstract [en]

A submarine eruption started off the south coast of El Hierro, Canary Islands, on 10 October 2011 and continues at the time of this writing (February 2012). In the first days of the event, peculiar eruption products were found floating on the sea surface, drifting for long distances from the eruption site. These specimens, which have in the meantime been termed "restingolites" (after the close-by village of La Restinga), appeared as black volcanic "bombs" that exhibit cores of white and porous pumice-like material. Since their brief appearance, the nature and origin of these "floating stones" has been vigorously debated among researchers, with important implications for the interpretation of the hazard potential of the ongoing eruption. The "restingolites" have been proposed to be either (i) juvenile high-silica magma (e. g. rhyolite), (ii) remelted magmatic material (trachyte), (iii) altered volcanic rock, or (iv) reheated hyaloclastites or zeolite from the submarine slopes of El Hierro. Here, we provide evidence that supports yet a different conclusion. We have analysed the textures and compositions of representative "restingolites" and compared the results to previous work on similar rocks found in the Canary Islands. Based on their high-silica content, the lack of igneous trace element signatures, the presence of remnant quartz crystals, jasper fragments and carbonate as well as wollastonite (derived from thermal overprint of carbonate) and their relatively high oxygen isotope values, we conclude that "restingolites" are in fact xenoliths from pre-island sedimentary layers that were picked up and heated by the ascending magma, causing them to partially melt and vesiculate. As they are closely resembling pumice in appearance, but are xenolithic in origin, we refer to these rocks as "xeno-pumice". The El Hierro xeno-pumices hence represent messengers from depth that help us to understand the interaction between ascending magma and crustal lithologies beneath the Canary Islands as well as in similar Atlantic islands that rest on sediment-covered ocean crust (e. g. Cape Verdes, Azores). The occurrence of "restingolites" indicates that crustal recycling is a relevant process in ocean islands, too, but does not herald the arrival of potentially explosive high-silica magma in the active plumbing system beneath El Hierro.

Place, publisher, year, edition, pages
Copernicus Publications, 2012
National Category
Geology Geochemistry
Identifiers
urn:nbn:se:uu:diva-171483 (URN)10.5194/se-3-97-2012 (DOI)000309884400008 ()
Funder
Swedish Research Council
Note

Correction in Solid Earth. Vol. 3(2) p. 189. DOI: 10.5194/se-3-189-2012

Available from: 2012-03-19 Created: 2012-03-19 Last updated: 2019-10-03Bibliographically approved
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