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- 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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- 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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- Deegan, Frances, et al.
(författare)
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Magma-Shale Interaction in Large Igneous Provinces : Implications for Climate Warming and Sulfide Genesis
- 2022
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Ingår i: Journal of Petrology. - : Oxford University Press. - 0022-3530 .- 1460-2415. ; 63:9
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Tidskriftsartikel (refereegranskat)abstract
- Large igneous provinces (LIPs) whose magma plumbing systems intersect sedimentary basins are linked to upheavals of Earths carbon and sulfur cycles and thus climate and life history. However, the underlying mechanistic links between these phenomena are elusive. We address this knowledge gap through short time-scale petrological experiments (1200 degrees C and 150 MPa) that explore interaction between basaltic melt and carbonaceous shale (mudstone) using starting materials from the Canadian High Arctic LIP and the Sverdrup Basin in which it intrudes. Here we show that entrainment of shale xenoliths in basaltic melt causes shale to shatter due to incipient thermal stress and devolatilization, which accelerates assimilation by increasing reactive surface area. Shale assimilation therefore facilitates transfer of sediment-derived volatile elements to LIP magma plumbing systems, whereupon carbon dominates the vapor phase while sulfur is partitioned into sulfide melt droplets. This study reveals that although carbon and sulfur are efficiently mobilized as a consequence of shale assimilation, sulfides can sequester sulfuran important climate cooling agentthus enhancing net emissions of climate warming greenhouse gases by shale-intersecting LIPs.
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- 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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- Geiger, Harri, et al.
(författare)
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Multi-level magma plumbing at Agung and Batur volcanoes increases risk of hazardous eruptions
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The island of Bali in Indonesia is home to two active stratovolcanoes, Agung and Batur, but relatively little is known of their underlying magma plumbing systems. Here we define magma storage depths and isotopic evolution of the 1963 and 1974 eruptions using mineral-melt equilibrium thermobarometry and oxygen and helium isotopes in mineral separates. Olivine crystallised from a primitive magma and has average delta O-18 values of 4.8%. Clinopyroxene records magma storage at the crust-mantle boundary, and displays mantle-like isotope values for Helium (8.62 R-A) and delta O-18 (5.0-5.8%). Plagioclase reveals crystallisation in upper crustal storage reservoirs and shows delta O-18 values of 5.5-6.4%. Our new thermobarometry and isotope data thus corroborate earlier seismic and InSAR studies that inferred upper crustal magma storage in the region. This type of multi-level plumbing architecture could drive replenishing magma to rapid volatile saturation, thus increasing the likelihood of explosive eruptions and the consequent hazard potential for the population of Bali.
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