Water content of the mantle xenoliths from Kimberley and implications for explaining textural variations in cratonic roots

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.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.This work was supported by the Russian Science Foundation under Grant No 16-17-10067.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.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.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).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.

Download Full-text

Water content in minerals of mantle xenoliths from the Udachnaya pipe kimberlites (Yakutia)

Russian Geology and Geophysics ◽

10.1016/j.rgg.2014.03.002 ◽

2014 ◽

Vol 55 (4) ◽

pp. 428-442 ◽

Cited By ~ 14

Author(s):

A.L. Ragozin ◽

A.A. Karimova ◽

K.D. Litasov ◽

D.A. Zedgenizov ◽

V.S. Shatsky

Keyword(s):

Water Content ◽

Mantle Xenoliths ◽

Udachnaya Pipe

Download Full-text

Origin of water in the mantle eclogites from the V. Grib kimberlite pipe, NW Russia

10.5194/egusphere-egu2020-298 ◽

2020 ◽

Author(s):

Elena Shchukina ◽

Mariya Kolesnichenko ◽

Elena Malygina ◽

Aleksey Agashev ◽

Dmitry Zedgenizov

Keyword(s):

Water Content ◽

Lithospheric Mantle ◽

Water Saturation ◽

Kimberlite Pipe ◽

Mantle Xenoliths ◽

Coarse Grained ◽

Infrared Spectrometry ◽

Tetrahedral Position ◽

Equilibrium Pressure ◽

Hydrous Minerals

The study of water content in the rock-forming minerals of mantle xenoliths, entrained in kimberlites, provides information about the water storage of the lithospheric mantle of ancient cratons. In mantle xenoliths, the water can be identified as several percentages by weight in hydrous minerals (e.g. phlogopite and amphibole) and up to 2000&#160;ppm in nominally anhydrous minerals (NAMs; olivine, pyroxene, and garnet). Since the hydrous phases occur sporadically in mantle xenoliths, their NAMs reserve the main water content in the lithospheric mantle.The water content in garnet and clinopyroxene from the mantle eclogites from the V.&#160;Grib kimberlite pipe (Arkhangelsk Diamondiferous Province, NW Russia) was analysed using Fourier transform infrared spectrometry. The studied samples are coarse-grained (grain sizes from 0.5&#8211;1.3&#160;cm) bimineralic (garnet and clinopyroxene) eclogites with accessories of phlogopite, ilmenite, and rutile. The samples include high-MgO (three samples) and low-MgO (six samples) groups. The eclogites are interpreted as metamorphosed fragments of oceanic crustal rocks (basalt and gabbro for low-MgO eclogites and picritic/MgO basalt and troctolite for high-MgO eclogites) emplaced into the lithospheric mantle via a subduction event at 2.8 Ga. Based on pressure-temperature estimates (44&#8211;78 kbar; 940&#176;C&#8211;1275&#176;C), eclogites were transported by kimberlite from the range of depths of about 160 to >200&#160;km.The results show that all clinopyroxene grains contain structural water in the amount of 39 to 111&#160;ppm, whereas only two garnet samples have detectable water in the amount of 211 and 337&#160;ppm. The water incorporation into the clinopyroxene is mostly linked to M2 sites and aluminium in the tetrahedral position. The water content in the majority of eclogite clinopyroxene positively correlates with the jadeite component. The low-MgO eclogites with oceanic gabbro precursor contain significantly higher water concentrations in omphacites (70&#8211;111&#160;ppm) and whole rock (35&#8211;224&#160;ppm) compared to those with the oceanic basalt protolith (49&#8211;73&#160;ppm and 20&#8211;36&#160;ppm, respectively). The proposed observation is also confirmed by the negative correlations of water content in clinopyroxenes with a La/Yb ratio in clinopyroxene and WR water content versus the WR Yb concentration. The equilibrium pressure could be an additional factor that controls the water incorporation into the clinopyroxene of the high-MgO group.Our results show that water content in the V.&#160;Grib pipe eclogites is not from the mantle metasomatism and therefore can reflect the water saturation of their protoliths. The eclogite portion of the lithospheric mantle beneath the V.&#160;Grib kimberlite pipe can have at least twice the water enrichment compared to peridotite sections, indicating that an Archean subduction event played an essential role in the water saturation of the mantle.This work was supported by the Russian Science Foundation under grant no. 16-17-10067

Download Full-text

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

American Mineralogist ◽

10.2138/am-2020-7316 ◽

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.

Download Full-text

WATER CONTENT IN MINERALS OF MANTLE XENOLITHS FROM THE UDACHNAYA PIPE KIMBERLITES (Yakutia)

Геология и геофизика ◽

10.15372/gig20140402 ◽

2014 ◽

Vol 55 (4) ◽

Keyword(s):

Water Content ◽

Mantle Xenoliths ◽

Udachnaya Pipe

Download Full-text

Characterization of frozen hydrated biological specimens by low-loss EELS

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100132492 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1572-1573

Author(s):

Songquan Sun ◽

Richard D. Leapman

Keyword(s):

Water Content ◽

Direct Method ◽

Internal Standard ◽

Dry Weight ◽

Dark Field ◽

Protein Solutions ◽

Subcellular Compartment ◽

Differential Shrinkage ◽

Electron Energy Loss

Analyses of ultrathin cryosections are generally performed after freeze-drying because the presence of water renders the specimens highly susceptible to radiation damage. The water content of a subcellular compartment is an important quantity that must be known, for example, to convert the dry weight concentrations of ions to the physiologically more relevant molar concentrations. Water content can be determined indirectly from dark-field mass measurements provided that there is no differential shrinkage between compartments and that there exists a suitable internal standard. The potential advantage of a more direct method for measuring water has led us to explore the use of electron energy loss spectroscopy (EELS) for characterizing biological specimens in their frozen hydrated state.We have obtained preliminary EELS measurements from pure amorphous ice and from cryosectioned frozen protein solutions. The specimens were cryotransfered into a VG-HB501 field-emission STEM equipped with a 666 Gatan parallel-detection spectrometer and analyzed at approximately −160 C.

Download Full-text

STEM measurement of subcellular water distributions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100148678 ◽

1993 ◽

Vol 51 ◽

pp. 568-569

Author(s):

R.D. Leapman ◽

S.Q. Sun ◽

S-L. Shi ◽

R.A. Buchanan ◽

S.B. Andrews

Keyword(s):

Water Content ◽

Internal Standard ◽

Dry Weight ◽

Dry Mass ◽

Scanning Transmission Electron Microscope ◽

Dark Field ◽

Bulk Water ◽

Inelastic Electron ◽

Scanning Transmission ◽

Annular Dark Field

Recent advances in rapid-freezing and cryosectioning techniques coupled with use of the quantitative signals available in the scanning transmission electron microscope (STEM) can provide us with new methods for determining the water distributions of subcellular compartments. The water content is an important physiological quantity that reflects how fluid and electrolytes are regulated in the cell; it is also required to convert dry weight concentrations of ions obtained from x-ray microanalysis into the more relevant molar ionic concentrations. Here we compare the information about water concentrations from both elastic (annular dark-field) and inelastic (electron energy loss) scattering measurements.In order to utilize the elastic signal it is first necessary to increase contrast by removing the water from the cryosection. After dehydration the tissue can be digitally imaged under low-dose conditions, in the same way that STEM mass mapping of macromolecules is performed. The resulting pixel intensities are then converted into dry mass fractions by using an internal standard, e.g., the mean intensity of the whole image may be taken as representative of the bulk water content of the tissue.

Download Full-text