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Geochemistry of eclogite xenoliths from the Udachnaya Kimberlite Pipe: Section of ancient oceanic crust sampled. / Agashev, A. M.; Pokhilenko, L. N.; Pokhilenko, N. P. et al.

In: Lithos, Vol. 314-315, 01.08.2018, p. 187-200.

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Agashev AM, Pokhilenko LN, Pokhilenko NP, Shchukina EV. Geochemistry of eclogite xenoliths from the Udachnaya Kimberlite Pipe: Section of ancient oceanic crust sampled. Lithos. 2018 Aug 1;314-315:187-200. doi: 10.1016/j.lithos.2018.05.027

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Agashev, A. M. ; Pokhilenko, L. N. ; Pokhilenko, N. P. et al. / Geochemistry of eclogite xenoliths from the Udachnaya Kimberlite Pipe: Section of ancient oceanic crust sampled. In: Lithos. 2018 ; Vol. 314-315. pp. 187-200.

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@article{20705438a98f40d79025669de70fd589,
title = "Geochemistry of eclogite xenoliths from the Udachnaya Kimberlite Pipe: Section of ancient oceanic crust sampled",
abstract = "A suite of seventeen unique, large, and fresh eclogite xenoliths from the Udachnaya pipe have been studied for their whole-rock and mineral major- and trace-element compositions. Based on their major-element compositions, the Udachnaya eclogites can be subdivided in two groups: high magnesian (Mg# 68.8–81.9) and low magnesian (Mg# 56.8–59). The two eclogite groups are clearly different in the style of correlation between major elements. Positive correlations of FeO and CaO with MgO are observed in the low-magnesian group, whereas these correlations are negative in the high-magnesian group. In terms of trace element composition, the Udachnaya eclogites are enriched over Primitive Mantle, but comparable to mid-ocean-ridge basalt composition, except for significant enrichment in large-ion lithophile elements (LILE; Rb, Ba, K, Sr). Most of the samples show a positive Eu anomaly, irrespective of group. Reconstructed whole-rock composition from clinopyroxene and garnet modal abundances contains much less incompatible elements (LILE, light rare earth elements, high field strength elements) than measured composition. Approximately 60 to 100% of the middle rare earth elements, Zr, and Hf, and nearly 100% of the heavy rare earth elements, Co, V, and Sc of the whole-rock budget are concentrated in Gar and Cpx. Variations in major element compositions cover a full section of the modern and Archaean oceanic crust, from troctolite, through gabbroic rocks, to basalts. The low-Mg# eclogites could have formed from upper oceanic crust protoliths, being a mixture of basalts and gabbro, whereas the high-Mg# eclogites are originated from gabbro-troctolite section of the lower oceanic crust. Concordant variations of Eu anomaly with the Lu/Sr ratio and the V and Ni contents in the eclogite compositions are in agreement with the fractionation of plagioclase, clinopyroxene, and olivine in their low-pressure precursor rocks. Negative correlations of SiO2 and MgO, and a low Nd/YbNMORB ratio, in the low-Mg# eclogites are in agreement with partial melt loss, but the presence of accessory quartz limits the degree of melting to 13%. Major and trace element compositions suggest that the high-Mg# eclogites, and, consequently, the lower oceanic crust, could not have experienced significant melt loss, and subduction in the Archaean may have been essentially dry, compared to the present day.",
keywords = "Eclogite, Geochemistry, Lithospheric mantle, Oceanic crust, Subduction, Xenolith, SOUTH-AFRICA, WEST-AFRICA, LITHOSPHERIC MANTLE, SUBDUCTION ZONES, SIBERIA, WHOLE-ROCK, TRACE-ELEMENTS, MGO ECLOGITES, CONSTRAINTS, DIAMOND-BEARING ECLOGITE",
author = "Agashev, {A. M.} and Pokhilenko, {L. N.} and Pokhilenko, {N. P.} and Shchukina, {E. V.}",
note = "Publisher Copyright: {\textcopyright} 2018 Elsevier B.V.",
year = "2018",
month = aug,
day = "1",
doi = "10.1016/j.lithos.2018.05.027",
language = "English",
volume = "314-315",
pages = "187--200",
journal = "Lithos",
issn = "0024-4937",
publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - Geochemistry of eclogite xenoliths from the Udachnaya Kimberlite Pipe: Section of ancient oceanic crust sampled

AU - Agashev, A. M.

AU - Pokhilenko, L. N.

AU - Pokhilenko, N. P.

AU - Shchukina, E. V.

N1 - Publisher Copyright: © 2018 Elsevier B.V.

PY - 2018/8/1

Y1 - 2018/8/1

N2 - A suite of seventeen unique, large, and fresh eclogite xenoliths from the Udachnaya pipe have been studied for their whole-rock and mineral major- and trace-element compositions. Based on their major-element compositions, the Udachnaya eclogites can be subdivided in two groups: high magnesian (Mg# 68.8–81.9) and low magnesian (Mg# 56.8–59). The two eclogite groups are clearly different in the style of correlation between major elements. Positive correlations of FeO and CaO with MgO are observed in the low-magnesian group, whereas these correlations are negative in the high-magnesian group. In terms of trace element composition, the Udachnaya eclogites are enriched over Primitive Mantle, but comparable to mid-ocean-ridge basalt composition, except for significant enrichment in large-ion lithophile elements (LILE; Rb, Ba, K, Sr). Most of the samples show a positive Eu anomaly, irrespective of group. Reconstructed whole-rock composition from clinopyroxene and garnet modal abundances contains much less incompatible elements (LILE, light rare earth elements, high field strength elements) than measured composition. Approximately 60 to 100% of the middle rare earth elements, Zr, and Hf, and nearly 100% of the heavy rare earth elements, Co, V, and Sc of the whole-rock budget are concentrated in Gar and Cpx. Variations in major element compositions cover a full section of the modern and Archaean oceanic crust, from troctolite, through gabbroic rocks, to basalts. The low-Mg# eclogites could have formed from upper oceanic crust protoliths, being a mixture of basalts and gabbro, whereas the high-Mg# eclogites are originated from gabbro-troctolite section of the lower oceanic crust. Concordant variations of Eu anomaly with the Lu/Sr ratio and the V and Ni contents in the eclogite compositions are in agreement with the fractionation of plagioclase, clinopyroxene, and olivine in their low-pressure precursor rocks. Negative correlations of SiO2 and MgO, and a low Nd/YbNMORB ratio, in the low-Mg# eclogites are in agreement with partial melt loss, but the presence of accessory quartz limits the degree of melting to 13%. Major and trace element compositions suggest that the high-Mg# eclogites, and, consequently, the lower oceanic crust, could not have experienced significant melt loss, and subduction in the Archaean may have been essentially dry, compared to the present day.

AB - A suite of seventeen unique, large, and fresh eclogite xenoliths from the Udachnaya pipe have been studied for their whole-rock and mineral major- and trace-element compositions. Based on their major-element compositions, the Udachnaya eclogites can be subdivided in two groups: high magnesian (Mg# 68.8–81.9) and low magnesian (Mg# 56.8–59). The two eclogite groups are clearly different in the style of correlation between major elements. Positive correlations of FeO and CaO with MgO are observed in the low-magnesian group, whereas these correlations are negative in the high-magnesian group. In terms of trace element composition, the Udachnaya eclogites are enriched over Primitive Mantle, but comparable to mid-ocean-ridge basalt composition, except for significant enrichment in large-ion lithophile elements (LILE; Rb, Ba, K, Sr). Most of the samples show a positive Eu anomaly, irrespective of group. Reconstructed whole-rock composition from clinopyroxene and garnet modal abundances contains much less incompatible elements (LILE, light rare earth elements, high field strength elements) than measured composition. Approximately 60 to 100% of the middle rare earth elements, Zr, and Hf, and nearly 100% of the heavy rare earth elements, Co, V, and Sc of the whole-rock budget are concentrated in Gar and Cpx. Variations in major element compositions cover a full section of the modern and Archaean oceanic crust, from troctolite, through gabbroic rocks, to basalts. The low-Mg# eclogites could have formed from upper oceanic crust protoliths, being a mixture of basalts and gabbro, whereas the high-Mg# eclogites are originated from gabbro-troctolite section of the lower oceanic crust. Concordant variations of Eu anomaly with the Lu/Sr ratio and the V and Ni contents in the eclogite compositions are in agreement with the fractionation of plagioclase, clinopyroxene, and olivine in their low-pressure precursor rocks. Negative correlations of SiO2 and MgO, and a low Nd/YbNMORB ratio, in the low-Mg# eclogites are in agreement with partial melt loss, but the presence of accessory quartz limits the degree of melting to 13%. Major and trace element compositions suggest that the high-Mg# eclogites, and, consequently, the lower oceanic crust, could not have experienced significant melt loss, and subduction in the Archaean may have been essentially dry, compared to the present day.

KW - Eclogite

KW - Geochemistry

KW - Lithospheric mantle

KW - Oceanic crust

KW - Subduction

KW - Xenolith

KW - SOUTH-AFRICA

KW - WEST-AFRICA

KW - LITHOSPHERIC MANTLE

KW - SUBDUCTION ZONES

KW - SIBERIA

KW - WHOLE-ROCK

KW - TRACE-ELEMENTS

KW - MGO ECLOGITES

KW - CONSTRAINTS

KW - DIAMOND-BEARING ECLOGITE

UR - http://www.scopus.com/inward/record.url?scp=85048717553&partnerID=8YFLogxK

U2 - 10.1016/j.lithos.2018.05.027

DO - 10.1016/j.lithos.2018.05.027

M3 - Article

AN - SCOPUS:85048717553

VL - 314-315

SP - 187

EP - 200

JO - Lithos

JF - Lithos

SN - 0024-4937

ER -

ID: 14047589