| 1. |
- Carracedo, Juan Carlos, et al.
(författare)
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The 2011 submarine volcanic eruption in El Hierro (Canary Islands)
- 2012
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Ingår i: Geology Today. - : Wiley. - 0266-6979 .- 1365-2451. ; 28:2, s. 53-58
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Forty years after the Teneguía Volcano (La Palma, 1971), a submarine eruption took place off the town of La Restinga, south of El Hierro, the smallest and youngest island of the Canarian Archipelago. Precursors allowed an early detection of the event and its approximate location, suggesting it was submarine. Uncertainties derived from insufficient scientific information available to the authorities during the eruption, leading to disproportionate civil protection measures, which had an impact on the island's economy—based primarily on tourism—while residents experienced extra fear and distress.
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| 2. |
- Lorenz, Henning, 1972-
(författare)
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The Swedish Deep Drilling Program: the quest for the Earth’s inner secrets
- 2009
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Ingår i: Geology Today. - : Blackwell Publishing Ltd.. - 0266-6979 .- 1365-2451. ; 25:6, s. 219-225
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Swedish Deep Drilling Program (SDDP) has been initiated to study fundamental problems of the dynamic Earth system, its natural history and evolution. Many key scientific questions can be addressed through in situ investigations only, requiring deep continental drilling. Some are unique to Scandinavia, most are of international interest and significance. At present, five core projects (Fig. 1) with international teams are integrating scientific problems with societal and industrial applications. If SDDP succeeds to attract the funding required, Sweden will have a number of world-class boreholes at key locations by 2020.
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| 3. |
- Budd, David A., et al.
(författare)
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Traversing nature's danger zone: getting up close with Sumatra's volcanoes
- 2012
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Ingår i: Geology Today. - : Wiley. - 0266-6979 .- 1365-2451. ; 28:2, s. 64-70
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Tidskriftsartikel (refereegranskat)abstract
- The Indonesian island of Sumatra, located in one of the most active zones of the Pacific Ring of Fire, is characterized by a chain of subduction-zone volcanoes which extend the entire length of the island. As a group of volcanic geochemists, we embarked upon a five-week sampling expedition to these exotic, remote, and in part explosive volcanoes (SAGE 2010; Sumatran Arc Geochemical Expedition). We set out to collect rock and gas samples from 17 volcanic centres from the Sumatran segment of the Sunda arc system, with the aim of obtaining a regionally significant sample set that will allow quantification of the respective roles of mantle versus crustal sources to magma genesis along the strike of the arc. Here we document our geological journey through Sumatra's unpredictable terrain, including the many challenges faced when working on active volcanoes in pristine tropical climes.
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| 4. |
- Deegan, Frances M, et al.
(författare)
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Fast and furious; crustal CO2 loss at Merapi volcano, Indonesia.
- 2011
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Ingår i: Geology Today. - : Wiley. - 0266-6979 .- 1365-2451. ; 27:2, s. 63-64
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- New experimental results show that when magma interacts with carbonate-rich crustal rock, such as limestone, it rapidly liberates crustal CO2, with potentially devastating repercussions for explosive volcanic behaviour.
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| 5. |
- Emeleus, C.H., et al.
(författare)
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Recent research developments on the Isle of Rum, NW Scotland
- 2011
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Ingår i: Geology Today. - : Wiley. - 0266-6979 .- 1365-2451. ; 27:5, s. 184-193
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Tidskriftsartikel (refereegranskat)abstract
- The appearance in 1997 of the British Geological Survey's memoir on Rum was followed by a period of intense research, leading to upwards of 35 papers, books and other articles. The scope of these publications, and the research progress over the last 15 years since publication of the memoir, is reviewed here. Igneous activity on Rum was short lived, possibly only ca. 500 ka, and, at about 60.5 Ma. The Rum central complex thus pre-dates the nearby Skye central complex. The earliest, acidic and mixed acidic/basic magmatism on Rum involved both shallow intrusions and ignimbrite eruptions into a collapsing caldera bound by the Main Ring Fault, a structure which probably also exercised a structural influence on subsequent mafic and ultrabasic magmatism. Subsequent emplacement of gabbros and ultrabasic rocks caused only limited thermal metamorphism of the surrounding Torridonian sandstones, contrasting markedly with the intense alteration of uplifted masses of Lewisian gneiss within the ring fault. Detailed textural studies on the gabbroic and ultrabasic rocks allow distinction between intrusive peridotites and peridotite that formed as part of the classic layered units of Rum and, furthermore, this work and that on the chromite seams and veins in these rocks shows that movements of trapped magma and magma derived from later intrusions, may produce textures and structures hitherto regarded as primary features of cumulate rocks. Rare picritic dykes provide an indication of likely parent magma for the mafic and ultrabasic rocks, but these and other magmatic rocks on Rum have all undergone varying degrees of crustal contamination, involving both Lewisian granulite and amphibolite crust but, notably, not Moine rocks as at Ardnamurchan. Sulphides in the chromite seams and ultrabasic rocks show possible influences from assimilated Jurassic sediments. From recent apatite fission track studies it seems likely that Rum, in common with other Palaeogene centres, underwent a brief, but significantly younger (Mesozoic) heating event.
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| 6. |
- Gertisser, R., et al.
(författare)
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Merapi (Java, Indonesia): anatomy of a killer volcano
- 2011
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Ingår i: Geology Today. - : Wiley. - 0266-6979 .- 1365-2451. ; 27:2, s. 57-62
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Merapi is Indonesia's most dangerous volcano with a history of deadly eruptions. Over the past two centuries, the volcanic activity has been dominated by prolonged periods of lava dome growth and intermittent gravitational or explosive dome failures to produce pyroclastic flows every few years. Explosive eruptions, such as in 2010, have occurred occasionally during this period, but were more common in pre-historical time, during which a collapse of the western sector of the volcano occurred at least once. Variations in magma supply from depth, magma ascent rates and the degassing behaviour during ascent are thought to be important factors that control whether Merapi erupts effusively or explosively. A combination of sub-surface processes operating at relatively shallow depth inside the volcano, including complex conduit processes and the release of carbon dioxide into the magmatic system through assimilation of carbonate crustal rocks, may result in unpredictable explosive behaviour during periods of dome growth. Pyroclastic flows generated by gravitational or explosive lava dome collapses and subsequent lahars remain the most likely immediate hazards near the volcano, although the possibility of more violent eruptions that affect areas farther away from the volcano cannot be fully discounted. In order to improve hazard assessment during future volcanic crises at Merapi, we consider it crucial to improve our understanding of the processes operating in the volcano's plumbing system and their surface manifestations, to generate accurate hazard zonation maps that make use of numerical mass flow models on a realistic digital terrain model, and to utilize probabilistic information on eruption recurrence and inundation areas.
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| 7. |
- Ahlberg, Per E., et al.
(författare)
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There's a ratfish in our cellar!
- 1997
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Ingår i: Geology Today. - 0266-6979 .- 1365-2451. ; 13, s. 20-23
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Berg, Sylvia, et al.
(författare)
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Iceland's best kept secret
- 2014
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Ingår i: Geology Today. - : Wiley. - 0266-6979 .- 1365-2451. ; 30:2, s. 54-60
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Tidskriftsartikel (refereegranskat)abstract
- The ‘forgotten fjords’ and ‘deserted inlets’ of NE-Iceland, in the region between Borgarfjörður Eystri and Loðmundarfjörður, are not only prominent because of their pristine landscape, their alleged elfin settlements, and the puffins that breed in the harbour, but also for their magnificent geology. From a geological point of view, the area may hold Iceland's best kept geological secret. The greater Borgarfjörður Eystri area hosts mountain chains that consist of voluminous and colourful silicic rocks that are concentrated within a surprisingly small area (Fig. 1), and that represent the second-most voluminous occurrence of silicic rocks in the whole of Iceland. In particular, the presence of unusually large volumes of ignimbrite sheets documents extremely violent eruptions during the Neogene, which is atypical for this geotectonic setting. As a group of geoscientists from Uppsala University (Sweden) and the Nordic Volcanological Center (NordVulk, Iceland) we set out to explore this remote place, with the aim of collecting material that may allow us to unravel the petrogenesis of these large volumes of silicic rocks. This effort could provide an answer to a long-standing petrological dilemma; the question of how silicic continental crust is initially created. Here we document on our geological journey, our field strategy, and describe our field work in the remote valleys of NE-Iceland.
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| 9. |
- Carracedo, Juan-Carlos, et al.
(författare)
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Volcanic and structural evolution of Pico do Fogo, Cape Verde
- 2015
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Ingår i: Geology Today. - : Wiley. - 0266-6979 .- 1365-2451. ; 31:4, s. 146-152
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Tidskriftsartikel (refereegranskat)abstract
- In recent months the media have drawn attention to the Cape Verde archipelago, with particular focus on the island of Fogo, the only island presently active and with an eruption that began on 23 November 2014, finally ceasing on 7 February 2015. The Monte Amarelo conical shield forms most of the 476 km2 almost circular island of Fogo. After attaining a critical elevation of about 3500 m, the Monte Amarelo shield volcano was decapitated by a giant landslide that formed a caldera-like depression (Cha das Caldeiras), which was subsequently partially filled by basaltic nested volcanism. This younger eruptive activity culminated in the construction of the 2829 m-high Pico do Fogo stratocone, apparently entirely made of layers of basaltic lapilli. Continued growth of the Pico do Fogo summit eruptions was interrupted in 1750, most likely after the stratocone reached a critical height. Since then, at least eight eruptions have taken place inside the landslide depression at the periphery of the Pico do Fogo cone, including the 2014–2015 eruptive event. Strong geological similarities with the Canary Islands, 1400 km to the north, have been frequently noted, probably as a consequence of a common process of origin and evolution associated with a mantle hot-spot. These similarities are particularly evident when comparing Fogo with the Teide Volcanic Complex on Tenerife, where a lateral collapse of the Las Cañadas stratovolcano also formed a large depression (the Caldera de Las Cañadas), now partially filled with the 3718 m-high Teide stratocone. However, important geological differences also exist and probably relate to the contrasting evolutionary stages of both islands. The Las Cañadas volcano on Tenerife formed at a late post-erosional stage, with predominantly evolved (trachyte and phonolite) magmas, while at Fogo basaltic volcanism is still dominant.
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| 10. |
- Deegan, Frances, et al.
(författare)
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The stiff upper LIP : investigating the High Arctic Large Igneous Province
- 2016
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Ingår i: Geology Today. - : Wiley. - 0266-6979 .- 1365-2451. ; 32:3, s. 92-98
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- The Canadian Arctic Islands expose a complex network of dykes and sills that belong to the High Arctic Large Igneous Province (HALIP), which intruded volatile-rich sedimentary rocks of the Sverdrup Basin (shale, limestone, sandstone and evaporite) some 130 to 120 million years ago. There is thus great potential in studying the HALIP to learn how volatile-rich sedimentary rocks respond to magmatic heating events during LIP emplacement. The HALIP remains, however, one of the least well known LIPs on the planet due to its remote location, short field season, and harsh climate. A Canadian–Swedish team of geologists set out in summer 2015 to further explore HALIP sills and their sedimentary host rocks, including the sampling of igneous and meta-sedimentary rocks for subsequent geochemical analysis, and high pressure-temperature petrological experiments to help define the actual processes and time-scales of magma–sediment interaction. The research results will advance our understanding of how climate-active volatiles such as CO2, SO2 and CH4 are mobilised during the magma–sediment interaction related to LIP events, a process which is hypothesised to have drastically affected Earth's carbon and sulphur cycles. In addition, assimilation of sulphate evaporites, for example, is anticipated to trigger sulphide immiscibility in the magma bodies and in so doing could promote the formation of Ni-PGE ore bodies. Here we document the joys and challenges of ‘frontier arctic fieldwork’ and discuss some of our initial observations from the High Arctic Large Igneous Province.
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