scholarly journals Water contents in mantle xenoliths from the Colorado Plateau and vicinity: Implications for the mantle rheology and hydration-induced thinning of continental lithosphere

2008 ◽  
Vol 113 (B9) ◽  
Author(s):  
Zheng-Xue Anser Li ◽  
Cin-Ty A. Lee ◽  
Anne H. Peslier ◽  
Adrian Lenardic ◽  
Stephen J. Mackwell
Keyword(s):  
Colorado Plateau ◽  
Mantle Xenoliths ◽  
Continental Lithosphere ◽  
Mantle Rheology ◽  
Water Contents

Water contents of mantle xenoliths from Sytykanskaya kimberlite pipe (Yakutian diamondiferous province, Russia)

2020 ◽  
Author(s):  
Maria Kolesnichenko ◽  
Dmitriy Zedgenizov ◽  
Igor Ashchepkov
Keyword(s):  
Water Content ◽  
Chemical Properties ◽  
Kimberlite Pipe ◽  
Mantle Xenoliths ◽  
Absolute Amount ◽  
Natural Occurrence ◽  
Russian Science ◽  
Geophysical Research ◽  
Heterogeneous Distribution ◽  
Water Contents

<p>Water plays a key role in evolution and dynamic of the Earth. It can change physical and chemical properties of mantle minerals, or the part of the mantle, for instance, the effect on mineral deformation and its impact on mantle rheology (Miller et al., 1987). Mantle xenoliths from kimberlites are one of direct source of information on the petrology and geochemistry of the deep mantle rocks.</p><p>Sytykanskaya pipe located in the central part of Yakutian diamondiferous province is characterized by a large amount of deep-seated xenoliths which contain relics of fresh minerals, e.g. clinopyroxenes, garnets, olivines, phlogopites, amphiboles, chromites, ilmenites and some other rare phases (Ashchepkov et al., 2015). Moreover it is known that there are several processes which can affect the mantle xenoliths, including metasomatism. Five peridotite xenoliths have been studied in order to indentify water enrichment. Using calibration coefficients (Bell et al., 2003) we calculated water content in the olivines. Water contents in olivine range from 12 to 92 ppm. In previous research (Kolesnichenko et al., 2017) we have studied peridotites from Udachnaya kimberlite pipe and found similar water content in olivines (2-95 ppm). So, the variably low water contents suggest a heterogeneous distribution of water beneath the mantle, which can be connected with metasomatism of essentially dry diamondiferous cratonic roots by hydrous and carbonatitic agents, and its related hydration and carbonation of peridotite accompanied by oxidation and dissolution of diamonds.</p><p><em>This work was supported by the Russian Science Foundation under Grant No 16-17-10067.</em></p><p>Miller, G. H., Rossman, G. R., & Harlow, G. E. (1987). The natural occurrence of hydroxide in olivine. Physics and chemistry of minerals, 14(5), 461-472.</p><p>Ashchepkov, I. V., Logvinova, A. M., Reimers, L. F., Ntaflos, T., Spetsius, Z. V., Vladykin, N. V., & Palesskiy, V. S. (2015). The Sytykanskaya kimberlite pipe: Evidence from deep-seated xenoliths and xenocrysts for the evolution of the mantle beneath Alakit, Yakutia, Russia. Geoscience Frontiers, 6(5), 687-714.</p><p>Bell, D. R., Rossman, G. R., Maldener, J., Endisch, D., & Rauch, F. (2003). Hydroxide in olivine: A quantitative determination of the absolute amount and calibration of the IR spectrum. Journal of Geophysical Research: Solid Earth, 108(B2).</p><p>Kolesnichenko, M. V., Zedgenizov, D. A., Litasov, K. D., Safonova, I. Y., & Ragozin, A. L. (2017). Heterogeneous distribution of water in the mantle beneath the central Siberian Craton: Implications from the Udachnaya Kimberlite Pipe. Gondwana Research, 47, 249-266.</p>

Olivine water contents in the continental lithosphere and the longevity of cratons

Nature ◽  
2010 ◽  
Vol 467 (7311) ◽  
pp. 78-81 ◽  
Author(s):  
Anne H. Peslier ◽  
Alan B. Woodland ◽  
David R. Bell ◽  
Marina Lazarov
Keyword(s):  
Continental Lithosphere ◽  
Water Contents

scholarly journals In search for the missing arc root of the Southern California Batholith: P-T-t evolution of upper mantle xenoliths of the Colorado Plateau Transition Zone

2020 ◽  
Vol 547 ◽  
pp. 116447 ◽  
Author(s):  
Ojashvi Rautela ◽  
Alan D. Chapman ◽  
Jessie E. Shields ◽  
Mihai N. Ducea ◽  
Cin-Ty Lee ◽  
...  
Keyword(s):  
Transition Zone ◽  
Upper Mantle ◽  
Southern California ◽  
Colorado Plateau ◽  
Mantle Xenoliths ◽  
Arc Root

Is orthopyroxene really a reliable recorder of mantle water signatures? Insights from an experimental study

2020 ◽  
Author(s):  
Alexandra Demers-Roberge ◽  
Michael Jollands ◽  
Peter Tollan ◽  
Othmar Müntener
Keyword(s):  
Diffusion Coefficients ◽  
Mantle Xenoliths ◽  
Spinel Peridotite ◽  
Alkaline Magma ◽  
Silica Activity ◽  
Exponential Factors ◽  
Natural Olivine ◽  
Natural Settings ◽  
Water Contents

<p>Experiments have been conducted to assess the effects of temperature, oxygen fugacity, crystallographic orientation, silica activity and chemical composition on the diffusivity and substitution mechanisms of hydrogen in orthopyroxene (opx). Axially oriented ~cuboids of natural Tanzanian opx were dehydrated at 1 bar in a gas mixing furnace (H<sub>2</sub>-CO<sub>2</sub> mix) at three different oxygen fugacities (~QFM-1,~QFM+1, ~QFM-7), and two different silica activity buffers (olivine+pyroxene or pyroxene+quartz) between 700°C and 1000°C. Profiles of hydrogen content versus distance were extracted from experimental samples using Fourier-Transform Infrared (FTIR) spectroscopy, with diffusion coefficients extracted using relevant analytical solutions and numerical approximations of Fick’s second law. Diffusion is the fastest along [001] ( D<sub>[001]</sub>>D<sub>[010]</sub>>D<sub>[100]</sub>). Fitting the diffusion coefficients to the isobaric Arrhenius relationship (logD=logD<sub>0</sub>+(-Q/(2.303RT)) gives activation energies (Q) and pre-exponential factors (logD<sub>0</sub>) between 127 to 162 kJmol<sup>-1</sup> and –4.29 to -5.42  m<sup>2</sup>s<sup>-1</sup> , respectively, for ~QFM-1.</p><p>The extracted hydrogen diffusivities are faster than previously measured by 0.5 to 5 orders of magnitude at ~1000 °C and ~700°C, respectively (Carpenter (2003), Stalder and Skogby (2003), Stalder and Behrens (2006), Stalder and al. (2007)) and are slightly slower, but strikingly close, to those of the fastest experimentally-determined diffusivity of H in olivine (Kohlstedt and Mackwell, 1998), suggesting a mechanism akin to proton-polaron exchange. This presents a paradoxical decoupling between natural and experimental observations. In most cases for mantle xenoliths, natural olivine has low water contents (<35 ppm), or are dry, and show H diffusive loss of water, where natural opx contains between 10 and 460 ppm and rarely show H diffusive loss (Demouchy and Bolfan-Casanova (2016), suggesting opx is more capable of recording the mantle water signature. With hydrogen diffusivities of olivine and opx being quite similar, however, both minerals should suffer from the same rate of dehydration during ascent, thus show low or zero water content in natural settings, which is not the case. Therefore, the inference that pyroxenes are better recorder of water in the mantle (e.g. Warren et Hauri (2014), Peslier (2010)) cannot be a simple function of diffusivities. A case study on an opx crystal showing a dehydration profile from a spinel-peridotite xenolith, hosted in an alkaline magma, from Patagonia supports this. Using the H diffusion coefficients from this study, the calculated rates of ascent of the mantle xenolith in alkaline magma are comparable to those associated with kimberlite magmas. The two suggestions we present are the following: i) Changing the boundary conditions may modify the hydrogen diffusive flux through the xenolith history and ii) The measured diffusivities would be apparent diffusivities as there might be different pathways or mechanisms of diffusion.</p>

Evidence from mantle xenoliths for relatively thin (<100 km) continental lithosphere below the Phanerozoic crust of southernmost South America

Lithos ◽  
1999 ◽  
Vol 48 (1-4) ◽  
pp. 217-235 ◽  
Author(s):  
Charles R Stern ◽  
Rolf Kilian ◽  
Bettina Olker ◽  
Eric H Hauri ◽  
T.Kurtis Kyser
Keyword(s):  
South America ◽  
Mantle Xenoliths ◽  
Continental Lithosphere

Decoupled water and iron enrichments in the cratonic mantle: A study on peridotite xenoliths from Tok, SE Siberian Craton

2020 ◽  
Vol 105 (6) ◽  
pp. 803-819
Author(s):  
Luc S. Doucet ◽  
Yongjiang Xu ◽  
Delphine Klaessens ◽  
Hejiu Hui ◽  
Dmitri A. Ionov ◽  
...  
Keyword(s):  
Water Content ◽  
Siberian Craton ◽  
Lithospheric Mantle ◽  
Large Scale ◽  
Basaltic Magma ◽  
Mantle Xenoliths ◽  
Spinel Peridotite ◽  
Peridotite Xenoliths ◽  
Cratonic Mantle ◽  
Water Contents

Abstract Water and iron are believed to be key constituents controlling the strength and density of the lithosphere and, therefore, play a crucial role in the long-term stability of cratons. On the other hand, metasomatism can modify the water and iron abundances in the mantle and possibly triggers thermo-mechanical erosion of cratonic keels. Whether local or large scale processes control water distribution in cratonic mantle remains unclear, calling for further investigation. Spinel peridotite xenoliths in alkali basalts of the Cenozoic Tok volcanic field sampled the lithospheric mantle beneath the southeastern margin of the Siberian Craton. The absence of garnet-bearing peridotite among the xenoliths, together with voluminous eruptions of basaltic magma, suggests that the craton margin, in contrast to the central part, lost its deep keel. The Tok peridotites experienced extensive and complex metasomatic reworking by evolved, Ca-Fe-rich liquids that transformed refractory harzburgite to lherzolite and wehrlite. We used polarized Fourier transform infrared spectroscopy (FTIR) to obtain water content in olivine, orthopyroxene (Opx), and clinopyroxene (Cpx) of 14 Tok xenoliths. Olivine, with a water content of 0–3 ppm H2O, was severely degassed, probably during emplacement and cooling of the host lava flow. Orthopyroxene (49–106 ppm H2O) and clinopyroxene (97–300 ppm H2O) are in equilibrium. The cores of the pyroxene grains, unlike olivine, experienced no water loss due to dehydration or addition attributable to interaction with the host magma. The water contents of Opx and Cpx are similar to those from the Kaapvaal, Tanzania, and North China cratons, but the Tok Opx has less water than previously studied Opx from the central Siberian craton (Udachnaya, 28–301 ppm; average 138 ppm). Melting models suggest that the water contents of Tok peridotites are higher than in melting residues, and argue for a post-melting (metasomatic) origin. Moreover, the water contents in Opx and Cpx of Tok peridotites are decoupled from iron enrichments or other indicators of melt metasomatism (e.g., CaO and P2O5). Such decoupling is not seen in the Udachnaya and Kaapvaal peridotites but is similar to observations on Tanzanian peridotites. Our data suggest that iron enrichments in the southeastern Siberian craton mantle preceded water enrichment. Pervasive and large-scale, iron enrichment in the lithospheric mantle may strongly increase its density and initiate a thermo-magmatic erosion. By contrast, the distribution of water in xenoliths is relatively “recent” and was controlled by local metasomatic processes that operate shortly before the volcanic eruption. Hence, water abundances in minerals of Tok mantle xenoliths appear to represent a snapshot of water in the vicinity of the xenolith source regions.

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