Multi-stage magma ascent beneath the Canary Islands: evidence from fluid inclusions

1998 ◽  
Vol 132 (1) ◽  
pp. 48-64 ◽  
Author(s):  
Thor H. Hansteen ◽  
Andreas Klügel ◽  
Hans-Ulrich Schmincke
Keyword(s):  
Canary Islands ◽  
Fluid Inclusions ◽  
Magma Ascent ◽  
Multi Stage

Melt and fluid inclusions in dunite xenoliths from La Gomera, Canary Islands: tracking the mantle metasomatic fluids

1994 ◽  
Vol 6 (6) ◽  
pp. 805-818 ◽  
Author(s):  
Maria-Luce Frezzotti ◽  
Jacques L.R. Touret ◽  
Wim J. Lustenhouwer ◽  
Else-Ragnild Neumann
Keyword(s):  
Canary Islands ◽  
Fluid Inclusions ◽  
Melt And Fluid Inclusions ◽  
La Gomera

Manganoan fayalite and products of its alteration from the Strzegom pegmatites, Poland

1989 ◽  
Vol 53 (371) ◽  
pp. 315-325 ◽  
Author(s):  
J. Janeczek
Keyword(s):  
Hydrothermal Alteration ◽  
Fluid Inclusions ◽  
Iron Hydroxide ◽  
Silicate Phase ◽  
Second Stage ◽  
Multi Stage ◽  
Composite Mixture ◽  
Quartz Aggregates ◽  
Lower Silesia

AbstractNodules of manganoan fayalite occur in schlieren pegmatities in the vicinity of Strzegom, Lower Silesia. The fayalite, Na0.02(Fe1.812+Mn0.16Mg 0.03)Si0.99O4, is unzoned and non pleochroic. 2Va = 42° a 4.826(3), b 10.500(2), c 6.102(2) A, d130obs. = 2.83 Å, d130calc. = 2.833 Å, D = 4.35 g cm-3, Dcalc. = 4.353 g cm-3. The role of Na+ ions in the fayalite chemistry is discussed. The fayalite underwent multi-stage hydrothermal alteration beginning at the highest temperature (440°C) of homogenization of gaseous-fluid inclusions in quartz adjacent to the fayalite grains. Increase in fO2 and then in PH2O resulted in the formation of magnetite-quartz and Mn-grunerite-magnetite-quartz aggregates within the fayalite grains. The fayalite is mantled by a Mn-greenalite-magnetite rim, Mn-grunerite-magnetite-Mn-minnesotaite zone in a stilpnomelane or greenalite-rich groundmass. The minnesotaite is believed to have formed at the expense of grunerite. Stilpnomelane, the most abundant silicate phase in the rim, is the product of biotite and presumably greenalite alteration at the second stage of increasing Na activity (the crystallization of cleavelandite) in the pegmatites. The fayalite is also heavily altered to iddingsite—a composite mixture of amorphous FeOOH and silica. The iron-hydroxide recrystallized partially to poorly-crystalline goethite.

Xenopumices from the 2011-2012 submarine eruption of El Hierro (Canary Islands, Spain): Constraints on the plumbing system and magma ascent

2012 ◽  
Vol 39 (17) ◽  
pp. n/a-n/a ◽  
Author(s):  
S. Meletlidis ◽  
A. Di Roberto ◽  
M. Pompilio ◽  
A. Bertagnini ◽  
I. Iribarren ◽  
...  
Keyword(s):  
Canary Islands ◽  
Magma Ascent ◽  
Submarine Eruption ◽  
Plumbing System ◽  
El Hierro

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>

Fluids in Hercynian Au veins from the French Variscan belt

1990 ◽  
Vol 54 (375) ◽  
pp. 231-243 ◽  
Author(s):  
M. C. Boiron ◽  
M. Cathelineau ◽  
J. Dubessy ◽  
A. M. Bastoul
Keyword(s):  
High Temperature ◽  
Fluid Inclusions ◽  
Genetic Relationships ◽  
Hydrothermal Systems ◽  
Gold Deposition ◽  
Variscan Belt ◽  
Quartz Veins ◽  
Multi Stage ◽  
Montagne Noire ◽  
Host Rocks

AbstractFluids, together with alteration and ore mineral assemblages, were studied in representative hydrothermal gold-bearing quartz veins from the western part of the Variscan belt in France (La Bellière, Montagne Noire district, Villeranges-Le Châtelet district, and Limousin province). Petrographic studies of the relationships between ores, fluid inclusions, microfracturing and quartz textures show that chronological and genetic relationships between gold deposition and fluid trapping may be very complex and difficult to establish for veins which show multi-stage fracturing and shearing. Systematic studies of secondary fluid inclusions in microcracks and recrystallized zones of the early quartz veins indicate two contrasting physical-chemical conditions: 1 relatively high temperature (250–400°C) and pressure (>1 kbar) event with CO2-CH4-H2S-N2 (±H2O-NaCl)-rich fluids related to the early sulphide deposition; 2 lower temperature (150–250°C) and pressure with aqueous fluids related to the late native-gold-sulphide (or sulphosalt) assemblage, which constitutes the economic ores in some deposits.In deposits where gold occurs predominantly in a combined state within arsenopyrite and pyrite (Châtelet and Villeranges), primary fluid inclusions in authigenic quartz combs cogenetic with arsenopyrite are almost purely aqueous (H2O-NaCl) and have a low salinity (1–4 wt. % NaCl). P-T conditions (150–250°C), nearly hydrostatic pressures) are similar to those of the second stage in the multi-stage quartz veins.Consideration of chemical equilibria in the C-O-H-N-S system using microthermometric and Raman spectrometric analysis for the fluids, together with data obtained from mineralogical studies, show that during gold deposition, fO2 was below hematite-magnetite buffer at Villeranges and around the Ni-NiO buffer at La Bellière and Montagne Noire. fS2 calculations based on H2S analyses are in good agreement with mineral assemblage estimates and close to that fixed by the pyrite-pyrrhotite boundary at high temperature. Ore fluid pH was significantly lower than in the host rocks as shown by the complete alteration of the host rocks into a quartz-K-mica assemblage. The data illustrate that during the late Hercynian, fluid circulation evolved from high P-T conditions, in some cases linked to late magma intrusions, towards conditions typical of later hydrothermal systems of the geothermal type.

Rates of magma ascent and depths of magma reservoirs beneath La Palma (Canary Islands)

Terra Nova ◽  
1997 ◽  
Vol 9 (3) ◽  
pp. 117-121 ◽  
Author(s):  
Andreas Klügel ◽  
Thor H. Hansteen ◽  
Hans-Ulrich Schmincke
Keyword(s):  
Canary Islands ◽  
Magma Ascent ◽  
La Palma ◽  
Magma Reservoirs

CL for characterizing quartz and trapped fluid inclusions in mesothermal quartz veins: Muruntau Au ore deposit, Uzbekistan

2000 ◽  
Vol 64 (6) ◽  
pp. 1007-1016 ◽  
Author(s):  
T. Graupner ◽  
J. Götze ◽  
U. Kempe ◽  
D. Wolf
Keyword(s):  
Fluid Inclusions ◽  
Microstructural Analysis ◽  
Polarized Light ◽  
Video Camera ◽  
Quartz Veins ◽  
Digital Video Camera ◽  
Vein Formation ◽  
Primary Growth ◽  
Multi Stage ◽  
Growth Zoning

AbstractCombined cathodoluminescence (CL) and transmitted light microscopy were used to characterize quartz from flat and steeply dipping quartz veins and from veinlets in banded host rocks from the giant Muruntau Au quartz vein deposit, Kyzyl Kum Desert, western Uzbekistan. The CL examinations were carried out using a ‘hot-cathode’ CL microscope linked to a highly sensitive digital video camera. The multi-stage deformed flat quartz veins and the steeply dipping hydrothermal formations at Muruntau are characterized by quartz with different CL colours, internal structures and degree of secondary alteration. Primary growth zoning of quartz, indiscernible in conventional polarized light was found to occur only in steeply dipping veins. The bulk of the high-grade Au mineralized ‘central’ quartz veins is dominated by one generation of hydrothermal quartz; intense brecciation of these veins is indicated by the occurrence of fragments of zoned quartz crystals. Primary growth zoning in quartz may be revealed not only by variations in the intensity of blue CL and/or by primary fluid inclusions arranged within the zones, but also by secondary inclusions and recrystallization phenomena developed along boundary surfaces between the zones. Using the results from CL imaging and microstructural analysis of the quartz, fluid inclusions investigated earlier were assigned to genetic types; the evidence of probably primary inclusions is of considerable importance for further studies of the geochemical conditions during vein formation. Considering geological and mineralogical data, CL studies of vein quartz may help to reveal the history of precipitation, deformation and recrystallization processes in the Muruntau Au ore field.

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