scholarly journals Geochemistry and Fe speciation in active volcanic environments – the case of Fogo Island, Cape Verde

2019 ◽  
Vol 98 ◽  
pp. 06009
Author(s):  
Rosa Marques ◽  
Bruno J.C. Vieira ◽  
Maria Isabel Prudêncio ◽  
João Carlos Waerenborgh ◽  
Maria Isabel Dias ◽  
...  
Keyword(s):  
Lava Flow ◽  
Iron Oxides ◽  
Chemical Evolution ◽  
Cape Verde ◽  
Weathering Rate ◽  
Hydrothermal Processes ◽  
Fe Speciation ◽  
Geological Formations ◽  
Semi Arid ◽  
Recent Eruption

Topsoils developed in different geological formations/ages, and the top layer of the lava flow from the most recent eruption (2014/2015) of Fogo Island (Cape Verde archipelago), were studied. The specific objectives of this work are: i) to estimate the REE contents and patterns in the whole sample of topsoils developed on different geological formations/ages and their correlation with the iron speciation; and ii) to study the top layer of a lava flow from the most recent eruption after two years of exposure. REE contents are in general higher in the topsoils of the pre-caldera than in those developed on the post-caldera formation, particularly the light REE probably due to their incorporation into hematite. Positive Eu anomalies found in recent topsoils suggest the existence of hydrothermal processes with intrusion of hot fluids with higher concentration of Eu2+. In the top layer of the lava flow of the most recent eruption, Fe is incorporated in pyroxenes and iron oxides (magnetite and/or maghemite). This study can be a benchmark for further knowledge of the chemical evolution and weathering rate in semi-arid climate of Fogo Island.

Weathering on volcanic edifices under semi-arid climates. Insights from a regional assessment of the composition of Fogo Island regoliths (Cape Verde)

2021 ◽  
pp. SP520-2021-61
Author(s):  
Marina Cabral Pinto ◽  
Pedro A. Dinis ◽  
Denise Pitta Groz ◽  
Rosa Marques ◽  
Maria Isabel Prudêncio ◽  
...  
Keyword(s):  
Mobile Elements ◽  
Cape Verde ◽  
Regional Assessment ◽  
Pyroclastic Deposits ◽  
Basaltic Rocks ◽  
Basalt Weathering ◽  
Low Humidity ◽  
Moderate Elevation ◽  
Semi Arid ◽  
Climatic Features

AbstractIn this study, the geochemistry and mineralogy of regoliths formed on Fogo Island (Cape Verde), a polygenic stratovolcano built during the Quaternary, are used to assess the geomorphological factors that control the early stages of basalt weathering. Fogo Island soils are mainly derived from relatively homogenous silica-undersaturated basaltic rocks. However, a discernible exotic component is recognised in areas most exposed to prevailing winds by ratios on non-mobile elements that are hosted in different amounts by basaltic rocks (e.g., Th, Sc and Ti). Weathering extent is evidenced by a relative depletion in mobile elements (e.g., Na, Ca, Mg) and an enrichment in non-mobile elements (e.g., Ti, Fe, Sc, Al), the decomposition of the most labile minerals (olivines), and the enrichment in secondary components (phyllosilicates and some Fe-oxides, such as hematite-goethite), along with quartz supplied from non-volcanic areas. It depends on bedrock age and type (pyroclastic deposits vs. lava-flows). In particular, soils covering older volcanic units tend to be more affected by chemical alteration than those overlying younger units. In addition, more intense weathering is observed in locations characterised by a combination of moderate elevation, slopes with low gradient and relatively high rainfall. The present investigation shows that even in low humidity environments recently formed basalt are affected by weathering, with the extent of chemical decomposition being mainly determined by the age of surface exposure and local orographic/climatic features.

scholarly journals Gas Phase Chemical Evolution of Uranium, Aluminum, and Iron Oxides

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Batikan Koroglu ◽  
Scott Wagnon ◽  
Zurong Dai ◽  
Jonathan C. Crowhurst ◽  
Michael R. Armstrong ◽  
...  
Keyword(s):  
Gas Phase ◽  
Iron Oxides ◽  
Chemical Evolution ◽  
Aluminum And Iron Oxides ◽  
Phase Chemical

Formation of Nucleobases from Formamide in the Presence of Iron Oxides: Implication in Chemical Evolution and Origin of Life

Astrobiology ◽  
2011 ◽  
Vol 11 (3) ◽  
pp. 225-233 ◽  
Author(s):  
Uma Shanker ◽  
Brij Bhushan ◽  
G. Bhattacharjee ◽  
Kamaluddin
Keyword(s):  
Origin Of Life ◽  
Iron Oxides ◽  
Chemical Evolution

scholarly journals Recent eruption history inferred from eruption ages of the two latest lava flows using multi-dating at Yokodake Volcano, Japan

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Hiroya Nitta ◽  
Takeshi Saito ◽  
Yorinao Shitaoka
Keyword(s):  
Lava Flow ◽  
Volcanic Activity ◽  
Active Volcano ◽  
Lava Flows ◽  
Eruption Rate ◽  
Dating Methods ◽  
Paleomagnetic Dating ◽  
History Of ◽  
Eruption History ◽  
Recent Eruption

Abstract Reconstruction of the eruption history of an active volcano is necessary to elucidate its volcanic activity and to assess the probability of its volcanic eruption. Yokodake volcano in central Japan is the only active volcano among the Yatsugatake volcano group. It has effused nine lava flows, most of which have not been dated. For this study, we ascertained the eruption ages of the latest lava (Y9) and second most recent lava (Y8) using radiocarbon (14C), thermoluminescence (TL), and paleomagnetic dating methods. Results revealed the eruption ages of the two lava flows and the recent eruption history of Yokodake volcano. Yokodake volcano effused its Y8 lava flow at ca. 3.4 ka, ejected NYk-2 tephra with explosive eruption at ca. 2.4–2.2 ka, and effused the Y9 lava flow associated with Y9-T tephra at ca. 0.6 ka. Magma eruption rates of Yokodake at 34 ky and 3.4 ky were estimated as about 9 × 10−3 km3/ky and 1 × 10−2 km3/ky, indicating a stable eruption rate maintained during the past 34 ky. This result suggests that Yokodake volcano retains some potential for eruption, although the volcanic activity of the Yatsugatake volcanoes (10−1–10−2 km3/ky) has weakened over time.

scholarly journals Lava flow hazard modeling during the 2014-2015 Fogo eruption, Cape Verde

2016 ◽  
Vol 121 (4) ◽  
pp. 2290-2303 ◽  
Author(s):  
Annalisa Cappello ◽  
Gaetana Ganci ◽  
Sonia Calvari ◽  
Nemesio M. Pérez ◽  
Pedro A. Hernández ◽  
...  
Keyword(s):  
Lava Flow ◽  
Cape Verde ◽  
Hazard Modeling ◽  
Lava Flow Hazard

scholarly journals Lava flow hazard at Fogo Volcano, Cape Verde, before and after the 2014–2015 eruption

2016 ◽  
Author(s):  
Nicole Richter ◽  
Massimiliano Favalli ◽  
Elske de Zeeuw-van Dalfsen ◽  
Alessandro Fornaciai ◽  
Rui Manuel da Silva Fernandes ◽  
...  
Keyword(s):  
Lava Flow ◽  
Disaster Response ◽  
Cape Verde ◽  
Lava Flows ◽  
Flow Simulations ◽  
Topographic Information ◽  
Lava Flow Hazard ◽  
Before And After ◽  
Lava Flow Emplacement ◽  
Fogo Volcano

Abstract. Lava flow simulations help to better understand volcanic hazards and may assist emergency preparedness at active volcanoes. We show that at Fogo Volcano, Cape Verde, such simulations can explain the 2014–2015 lava flow crisis and therefore provide a valuable base to better prepare for the inevitable next eruption. In a rapid disaster response effort, we conducted topographic mapping in the field and a satellite based remote sensing analysis. We produced the first topographic model of the 2014–2015 lava flows from combined Terrestrial Laser Scanner (TLS) and photogrammetric data. This high resolution topographic information facilitates lava flow volume estimates of 43.7 × 106 m3 (+/−5.2 × 106 m3) from the vertical difference between pre- and post-eruptive topographies. Both, the pre-eruptive and updated Digital Elevation Models (DEMs) serve as the fundamental input parameters for lava flow simulations using the well-established DOWNFLOW algorithm. Based on thousands of simulations, we assess the lava flow hazard before and after the 2014–2015 eruption. We find that, although the lava flow hazard has changed significantly, it remains high at the locations of two villages that were destroyed during this eruption. This result is of particular importance as villagers have already started to rebuild the settlements. We also analyse satellite radar imagery acquired by the German TerraSAR-X (TSX) satellite to map lava flow emplacement over time. We obtain the lava flow boundaries every 6 days during the eruption which assists the interpretation and evaluation of the lava flow model performance. Based on this, we discuss how our study can help improving the general understanding of basaltic lava flow behavior. Our results highlight the fact that lava flow hazards change as a result of modifications of the local topography due to lava flow emplacement, which implies the need for up-to-date topographic information in order to assess lava flow hazards. We also emphasize that areas that were once overrun by lava flows are not necessarily "safer", even if local lava flow thicknesses exceed the average lava flow thickness. Our observations will be important for the next eruption of Fogo Volcano and have implications for future lava flow crises and disaster response efforts at basaltic volcanoes elsewhere in the world.

Sign in / Sign up

Export Citation Format

Share Document