TY - JOUR

T1 - Origin of Water in Mantle Eclogites from the V. Grib Kimberlite Pipe, NW Russia

AU - Agasheva, Elena V.

AU - Kolesnichenko, Maria V.

AU - Malygina, Elena V.

AU - Agashev, Alexey M.

AU - Zedgenizov, Dmitry A.

N1 - Funding Information: We would like to thank two anonymous reviewers for their comments and input that helped to improve this manuscript. The preparation of samples, FTIR analyses, scanning electron microscopy, and Raman spectroscopy were funded by the Russian Science Foundation, grant no. 16-17-10067. The electron microprobe and ICP-MS analyses were supported by the Russian Science Foundation under grant no. 20-77-10018. The fieldwork and sampling were conducted on state assignment by IGM SB RAS. The manuscript was presented in a conference according to the following link “https://meetingorganizer .copernicus.org/EGU2020/EGU2020-298.html”. Funding Information: We would like to thank two anonymous reviewers for their comments and input that helped to improve this manuscript. The preparation of samples, FTIR analyses, scanning electron microscopy, and Raman spectroscopy were funded by the Russian Science Foundation, grant no. 16-17-10067. The electron microprobe and ICP-MS analyses were supported by the Russian Science Foundation under grant no. 20-77-10018. The fieldwork and sampling were conducted on state assignment by IGM SB RAS. The manuscript was presented in a conference according to the following link ?https://meetingorganizer.copernicus.org/EGU2020/EGU2020-298.html?. Publisher Copyright: Copyright © 2021 Elena V. Agasheva et al. Exclusive Licensee GeoScienceWorld. Distributed under a Creative Commons Attribution License (CC BY 4.0).

PY - 2021

Y1 - 2021

N2 - The water content in the garnet and clinopyroxene in the mantle eclogites from the V. Grib kimberlite pipe (Arkhangelsk Diamondiferous Province, NW Russia) was analysed using Fourier transform infrared spectrometry. The results show that all clinopyroxene grains contained structural water at concentrations of 39 to 247 ppm, whereas two garnet samples contained detectable water at concentrations of 211 and 337 ppm. The low-MgO eclogites with oceanic gabbro precursors contained significantly higher water concentrations in the omphacites (70–247 ppm) and whole rock (35–224 ppm) compared to those with oceanic basalt protoliths (49–73 ppm and 20–36 ppm, respectively). The incorporation of water into the clinopyroxene may be associated with vacancies at the M2 site, Al in the tetrahedral position, and the elements that filled the M2 site (mostly Na and Ca). The highest water content in the omphacite was detected in a nonmetasomatised sample and was assumed to represent residual water that survived during subduction. Other eclogite samples showed signs of modal and/or cryptic metasomatism and contained less water in the omphacites compared to the nonmetasomatised sample. The water content was heterogeneous within the eclogite section of the sampled lithospheric mantle. The lack of distinct and uniform correlations between the indices of eclogite modification and their water content indicated that the saturation with water was disturbed during their residence within the lithospheric mantle.

AB - The water content in the garnet and clinopyroxene in the mantle eclogites from the V. Grib kimberlite pipe (Arkhangelsk Diamondiferous Province, NW Russia) was analysed using Fourier transform infrared spectrometry. The results show that all clinopyroxene grains contained structural water at concentrations of 39 to 247 ppm, whereas two garnet samples contained detectable water at concentrations of 211 and 337 ppm. The low-MgO eclogites with oceanic gabbro precursors contained significantly higher water concentrations in the omphacites (70–247 ppm) and whole rock (35–224 ppm) compared to those with oceanic basalt protoliths (49–73 ppm and 20–36 ppm, respectively). The incorporation of water into the clinopyroxene may be associated with vacancies at the M2 site, Al in the tetrahedral position, and the elements that filled the M2 site (mostly Na and Ca). The highest water content in the omphacite was detected in a nonmetasomatised sample and was assumed to represent residual water that survived during subduction. Other eclogite samples showed signs of modal and/or cryptic metasomatism and contained less water in the omphacites compared to the nonmetasomatised sample. The water content was heterogeneous within the eclogite section of the sampled lithospheric mantle. The lack of distinct and uniform correlations between the indices of eclogite modification and their water content indicated that the saturation with water was disturbed during their residence within the lithospheric mantle.

UR - http://www.scopus.com/inward/record.url?scp=85108638910&partnerID=8YFLogxK

U2 - 10.2113/2021/7866657

DO - 10.2113/2021/7866657

M3 - Article

AN - SCOPUS:85108638910

VL - 2021

SP - 1

EP - 18

JO - Lithosphere

JF - Lithosphere

SN - 1941-8264

IS - 1

ER -