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Determining the mantle δ18Ο signature of the 1730-1736 Timanfaya eruption, Lanzarote

Valentin R. Troll1,2 , Frances M. Deegan1, Lovisa Gleisner3 , Anders Scherstén3, Meritxell Aulinas4, Ilya N. Bindeman5, Juan C. Carracedo2

  • Affiliations: 1Department of Earth Sciences, Natural Resources & Sustainable Development (NRHU), and Center for Natural Hazards and Disaster Science (CNDS), Uppsala University, Uppsala, Sweden; 2Instituto de Estudios Ambientales y Recursos Naturales (i-UNAT), University of Las Palmas de Gran Canaria (ULPGC), Las Palmas de Gran Canaria, Spain; 3Department of Geology, Lund University, Lund, Sweden; 4Departament de Mineralogia, Petrologia i Geologia Aplicada, University of Barcelona, Barcelona, Spain; 5Department of Earth Sciences, University of Oregon, Eugene, USA

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 228

  • Programme No: 1.6.8

  • Theme 1 > Session 6

Abstract

The ca. 1730-1736 volcanism on Lanzarote is a matter of contention as some authors argue that the volcanic activity contradicts the hot spot model for the Canary archipelago. In addition, the compositional changes in the eruption sequence led to discussion on whether mantle source processes or crustal influences are the controlling factors for the observed compositional variability. Here we present 34 new δ18Ο values, coupled with new major and trace element data, from the second half of the Timanfaya eruption (ca. 1733-1736) to determine if crustal assimilation can be detected and to establish if primitive compositions display a MORB or a plume-type signature. Our results show a range of +4.87 to +5.65‰ (± 0.12; 2 sigma) for sampled lavas, whereas crustal xenoliths range from -9.52 to +23.74‰. The more evolved samples, in turn, show mildly elevated δ18Ο values, implying that crustal input occurred, but was localised and volumetrically limited (≤ 5 %). The most primitive samples in the collected lava suite yield values of ~ +4.9‰ and the combined lava samples average to ~ +5.3‰, thus providing a primary mantle derived magmatic range of +4.9 to +5.3‰. The most primitive values of the sampled lava suite are thus inconsistent with a pure upper mantle derivation (MORB= +5.5 to +5.7‰), but require a plume-type mantle input, implying that plume-fed hot-spot magmatism is a key contributor to volcanism on Lanzarote Island.