Vorsitzende der Sitzung
Session 5 - Volcanism on Ocean Islands
- Thor Hansteen (GEOMAR)
It is well-known that volcanic eruptions can largely affect climate. However, and although still poorly understood, the reverse is also true. Several studies have demonstrated that volcanism can be triggered or influenced by external climatic factors such as isostatic unloading due to ice-cap melting, sea-level changes or rainfall variability. Unravelling the impact of these climate variations...
Henry Seamount is a ∼700 m tall Cretaceous (126 Ma) volcano located 40 km southeast of El Hierro, Canary Islands. Its summit area shows areas with dense coverage by <22 ka old shell fragments from vesicomyid clams, a few living chemosymbiotic bivalves, and evidence for sites of weak fluid discharge. Grab sampling also recovered glassy heterolithologic tephra and dispersed basaltic rock...
Fogo, Cape Verde, located upon thick oceanic lithosphere provides a window into processes occurring in the mantle where recycled ocean crust in an upwelling mantle plume interacts with ambient mantle. We aim to investigate the nature of the lithologies of the mantle sources involved in the petrogenesis of historic volcanic rocks from Fogo. There are enclaves and mingling textures in the lavas...
Oceanic volcanism comprises several styles of magmatic processes that reflect the compositional diversity of the mantle sources involved. The study of oceanic volcanism has been focused mainly on oceanic island basalts (OIB) related to deep mantle upwellings such as hotspots with a well-defined age-progressive island-seamount tracks. There are, however, hundreds of thousands of other volcanic...
Mt. Etna is Europe’s largest active volcano, and is located directly at the Ionian coast of Sicily. The volcanic history of Etna has been derived from many studies of subaerial deposits. However, little is known about the geology and sedimentology of the continental margin adjacent to the magnificent volcanic edifice. Several well-known and widely distributed eruptions from Mt. Etna produced...
Magmatic processes inside the volcanic plumbing system beneath the Cumbre Vieja volcano (La Palma, Spain) are possible trigger mechanisms for the Tajogaite eruption (2021, La Palma, Spain). Combining petrological characteristics of the eruption products with the investigation of compositional heterogeneities inside clinopyroxene (in Mg, Fe, Al, Na, Ti) and olivine (in Mg, Fe, Ca, Mn) crystals...
Knowledge of diffusion of elements across zone boundaries within crystals and the calculation of associated timescales has aided our understanding of pre-eruption magmatic processes and, together with other contextual information (seismic data, volumes of erupted material), has helped inform monitoring and mitigation strategies at active volcanoes. In my research I am applying diffusion...
The topography associated with volcanic edifices can be significant, especially in marine and coastal settings where the true extent of an edifice is not obvious due to the submerged portion of its flanks. It is therefore common to assume that the topographic surface can be approximated as a half space during modelling. However, this has been confirmed to lead to important misinterpretations...
Volcanic flank/sector collapses have been linked to changes between the magma compositions erupted before and after the collapse [1, 2]. The Monte Amarelo collapse (MAC) on Fogo occurred around 68-83 ka [1, 3, 4] and formed a horseshoe-shaped scar; the site of many recent eruptions. In this study we used the stratigraphy of Day [5} to select 34 samples from two Formations which pre-date the...
Secondary volcanism, either the rejuvenated stage in oceanic islands and seamounts or associated with vents in the outer rise and elsewhere, is ubiquitous in the Nazca Plate. Recent findings from field mapping at the Juan Fernández Ridge (JFR) and reanalysis of dredged samples allow a better geochronological constrain and thus a more comprehensive appraisal of the physical forcings....
The Chatham Islands, located ~800 km east of New Zealand on the eastern Chatham Rise, comprise two main (Chatham and Pitt) and numerous smaller islands. The collision of the oceanic Hikurangi Plateau with the Chatham Rise jammed the long-lived subduction system, leading to the separation of Zealandia from Gondwana. The breakup was accompanied by volcanism on the Hikurangi Plateau (Hikurangi...