Petrogenesis of spinel harzburgite and dunite suite xenoliths from Lanzarote, eastern Canary Islands: Implications for the upper mantle

Lithos ◽  
1995 ◽  
Vol 35 (1-2) ◽  
pp. 83-107 ◽  
Author(s):  
E.-R. Neumann ◽  
E. Wulff-Pedersen ◽  
K. Johnsen ◽  
T. Andersen ◽  
E. Krogh
Keyword(s):  
Canary Islands ◽  
Upper Mantle

First assessment of the noble gas and CO2 isotopic composition of fluid inclusions hosted in mantle xenoliths from El Hierro (Canary Islands) 

2021 ◽  
Author(s):  
Andres Sandoval Velasquez ◽  
Andrea Luca Rizzo ◽  
Alessandro Aiuppa ◽  
Maria Luce Frezzotti ◽  
Samantha Remigi ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Oceanic Crust ◽  
Canary Islands ◽  
Fluid Inclusions ◽  
Upper Mantle ◽  
Noble Gas ◽  
Mantle Metasomatism ◽  
Mantle Xenoliths ◽  
Local Source ◽  
El Hierro

<p>Studying the isotopic composition of fluids trapped in mantle xenoliths opens avenues to understanding the origin and cycling of volatiles in the Earth’s upper mantle. Here, we present the first isotopic results for noble gases and CO<sub>2</sub> in fluid inclusions (FI) trapped in mantle xenoliths from El Hierro the youngest island of the Canarian archipelago. Our results are based on 6 mantle xenolith samples (3 Spinel-lherzolites and 3 Spinel-harzburgites) collected from the El Julan cliff valley (Oglialoro et al., 2017), from which we hand-picked crystals of Ol, Opx, and Cpx. Isotopic determinations were performed at the INGV (Sezione di Palermo) noble gas and stable isotopes laboratories, following the preparation methods and analytical procedures described in Rizzo et al. (2018 and references therein).</p><p>The Ne-Ar isotopic compositions reveal the presence of an atmospheric component in the FI. Most of the samples exhibit <sup>4</sup>He/<sup>20</sup>Ne ratios > 60, <sup>20</sup>Ne/<sup>22</sup>Ne ratios between 9.84 and 10.49, <sup>21</sup>Ne/<sup>22</sup>Ne ratios from 0.0295 to 0.0330, and <sup>40</sup>Ar/<sup>36</sup>Ar > 800, suggesting mixing between MORB-like mantle fluids and an air-derived component. We argue this latter may (at least in part) derive from upper mantle recycling of atmospheric fluids via paleo-subduction event(s). Excluding samples possibly affected by diffusive fractionation processes, the average Rc/Ra ratio (<sup>3</sup>He/<sup>4</sup>He ratio corrected for atmospheric contamination) measured in El Hierro xenoliths is ~7.45 + 0.26 Ra, within the MORB range (8 + 1 Ra; Graham, 2002). The He homogeneous signature of these xenoliths agrees well with the <sup>3</sup>He/<sup>4</sup>He compositions previously reported in lava phenocrysts and cumulates (Day and Hilton, 2011) and is slightly below the maximum ratios measured in groundwater samples during the 2012 volcanic unrest (~8.2 Ra; Padron et al., 2013). All these pieces of evidence argue against a primordial source involved in the local lithospheric mantle. Putting these data in the context of previous literature results for FI and surface gases in the Canary Islands (La Palma, La Gomera, Tenerife, Gran Canaria, and Lanzarote), we identify an eastward <sup>3</sup>He/<sup>4</sup>He decreasing trend that parallels a corresponding increase of the oceanic crust thickness. In addition to the mantle heterogeneity, we propose that part of the <sup>3</sup>He/<sup>4</sup>He east-to-west variation along the archipelago is caused by the variable thickness of the oceanic crust (and hence, different interactions with <sup>4</sup>He-rich crustal fluids during emplacement).</p><p>The FI δ<sup>13</sup>C(CO<sub>2</sub>) isotopic composition ranges from -2.38 to -1.23‰ in pyroxenes and -0.2 to +2.0‰ in olivine. These unusually positive δ<sup>13</sup>C compositions support the existence of a recycled crustal carbon component in the local source mantle, likely pointing to mantle metasomatism (Oglialoro et al., 2017) from fluids carrying carbon from subducted sediments and/or altered oceanic crust (AOC).</p>

scholarly journals Seismic properties of the upper mantle beneath Lanzarote (Canary Islands): Model predictions based on texture measurements by EBSD

2006 ◽  
Vol 428 (1-4) ◽  
pp. 65-85 ◽  
Author(s):  
Pierre Vonlanthen ◽  
Karsten Kunze ◽  
Luigi Burlini ◽  
Bernard Grobety
Keyword(s):  
Canary Islands ◽  
Upper Mantle ◽  
Seismic Properties ◽  
Model Predictions

Investigating Seismic Anisotropy of the Madeira and Canaries Hotspots Using Teleseismic and Local Shear-Wave Splitting with the SIGHT project

2020 ◽  
Author(s):  
David Schlaphorst ◽  
Graça Silveira ◽  
João Mata
Keyword(s):  
Iberian Peninsula ◽  
Shear Wave ◽  
Canary Islands ◽  
Upper Mantle ◽  
Seismic Anisotropy ◽  
Shear Wave Splitting ◽  
Western Africa ◽  
Wave Splitting ◽  
Local Shear ◽  
North Western

<p>Madeira and the Canary Islands, located in the eastern North Atlantic, are two of many examples of hotspot surface expressions. Their tracks have been reconstructed to past locations close to the south-western part of the Iberian Peninsula and north-western Africa, respectively. Furthermore, due to their close proximity, an interconnected origin of these two hotspots has been proposed but details remain unclear. A better understanding of the crust and upper mantle structure beneath these islands is needed to investigate this potential connection.</p><p>The subsurface structure has an influence on the stress field, which can be investigated studying seismic anisotropy patterns of the region. Seismic anisotropy leads to variations in the speed of seismic waves as a function of the direction of wave propagation. In the crust an orientation in the direction of maximum stress is observed, commonly being parallel to the alignment of fractures or cracks. In the upper mantle the orientation is influenced by mantle flow. A widely used method to identify anisotropy is the observation of shear-wave splitting of data from teleseismic events. In case of multiple anisotropic layers, including measurements from local events it is possible to distinguish crustal from upper mantle influences.</p><p>As part of the SIGHT project (SeIsmic and Geochemical constraints on the Madeira HoTspot), we carried out the first detailed study of seismic anisotropy beneath both archipelagos, using teleseismic SKS and local shear-wave splitting measurements of data collected from land stations of seismic networks located on Madeira and the Canary Islands.</p><p>Significant changes, both in orientation and delay time, can be observed on short length-scales on the order of tens of kilometres, matching major geological features such as, for example, the major rift zone on Madeira island. In a further step, we compare these results to previous studies of crustal and upper mantle anisotropy focusing on north-western Africa and the Iberian Peninsula to investigate the nature of the lithospheric corridor between the present day hotspot positions and the Atlas-Gibraltar region.</p><p>This is a contribution to project SIGHT (Ref. PTDC/CTA-GEF/30264/2017). The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL.</p>

scholarly journals New insight into the 2011-2012 unrest and eruption of El Hierro Island (Canary Islands) based on integrated geophysical, geodetical and petrological data

2015 ◽  
Vol 58 (5) ◽  
Author(s):  
Stavros Meletlidis ◽  
Alessio Di Roberto ◽  
Itahiza Domínguez Cerdeña ◽  
Massimo Pompilio ◽  
Laura García-Cañada ◽  
...  
Keyword(s):  
Canary Islands ◽  
Upper Mantle ◽  
Rift Zone ◽  
Ground Deformation ◽  
Magma Ascent ◽  
Research Approach ◽  
Magmatic Source ◽  
El Hierro ◽  
Vertical Ground ◽  
Insight Into

<p>A shallow water eruption started on October 10, 2011, ~2 km south off the coast of El Hierro (Canary Islands, Spain). The eruption lasted about five months and ended by early March 2012. Three months of unrest preceded this event with more than 10,000 localized earthquakes and up to 6 cm of vertical ground deformation. In the Canary Islands, this is the first eruption to be monitored by the network of Instituto Geográfico National (IGN) since the very beginning of the seismic unrest. This provided unprecedented time series that include geophysical (seismic and gravimetric), geodetic, geochemical and petrological data. In this work we discuss and interpret these data in order to describe the mechanisms of 2011-2012 El Hierro eruption, including ascent from magmatic source, a crustal storage, and the final intrusion in the South Rift before the eruption. Our research approach provides a multidisciplinary view of the dynamics of magma ascent and improves previous interpretations formulated during or shortly after the end of the eruption. According to our results, a major intrusion occurred beneath and around preexisting high-density magmatic bodies, localized at depth below the central part of the island. After a failed attempt to reach the surface through a low fractured zone located below the central-northern part of the island, the ascending magma finally found its way nearby the El Hierro South Rift Zone and erupted off the coast of La Restinga village, 350 m below sea level. The eruption was fed by the ascent of an important volume of material from the upper mantle that was emplaced near the crust-mantle boundary and progressively tapped during the eruption.</p>

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