TY - JOUR

T1 - Evidence for a subduction component in the diamond-bearing mantle of the Siberian craton

AU - Shatsky, V. S.

AU - Zedgenizov, D. A.

AU - Ragozin, A. L.

PY - 2016/1/1

Y1 - 2016/1/1

N2 - Evidence for the involvement of a subduction component in diamond formation is analyzed based on literature data and our studies. Examination of xenoliths of diamondiferous eclogites, including X-ray tomography analysis, testifies to the superposed character of most diamonds. Diamond generation is accompanied by the serious modification of eclogite substratum. Isotope-geochemical data show that the eclogites originated from oceanic-crust rocks. The oxygen isotope compositions of garnets and clinopyroxenes from websterite xenoliths are similar to the mantle average (5.3-5.6‰). The eclogite minerals vary considerably in oxygen isotope composition (δ18O of 5.3 to 12.4‰). Diamonds of eclogitic paragenesis predominate dramatically in the placers of the northeastern Yakutian diamondiferous province. In placer eclogitic diamonds, δ13C varies from -27.2 to -3‰ (= 28). In diamonds of ultrabasic paragenesis, the range of δ13C values is much narrower (from -7.1 to -0.5‰). All diamonds of variety V have a lighter carbon isotope composition (from -24.1 to -17.4‰). In a wide range of crystals with a contrasting carbon isotope composition, the isotope composition of the rim tends toward the average mantle value. This suggests that the eclogitic diamonds grew first with the participation of carbon from subducted continental crust and finally with the involvement of mantle carbon.

AB - Evidence for the involvement of a subduction component in diamond formation is analyzed based on literature data and our studies. Examination of xenoliths of diamondiferous eclogites, including X-ray tomography analysis, testifies to the superposed character of most diamonds. Diamond generation is accompanied by the serious modification of eclogite substratum. Isotope-geochemical data show that the eclogites originated from oceanic-crust rocks. The oxygen isotope compositions of garnets and clinopyroxenes from websterite xenoliths are similar to the mantle average (5.3-5.6‰). The eclogite minerals vary considerably in oxygen isotope composition (δ18O of 5.3 to 12.4‰). Diamonds of eclogitic paragenesis predominate dramatically in the placers of the northeastern Yakutian diamondiferous province. In placer eclogitic diamonds, δ13C varies from -27.2 to -3‰ (= 28). In diamonds of ultrabasic paragenesis, the range of δ13C values is much narrower (from -7.1 to -0.5‰). All diamonds of variety V have a lighter carbon isotope composition (from -24.1 to -17.4‰). In a wide range of crystals with a contrasting carbon isotope composition, the isotope composition of the rim tends toward the average mantle value. This suggests that the eclogitic diamonds grew first with the participation of carbon from subducted continental crust and finally with the involvement of mantle carbon.

KW - Diamond

KW - Eclogites

KW - Upper mantle

KW - Websterites

UR - http://www.scopus.com/inward/record.url?scp=84958660748&partnerID=8YFLogxK

U2 - 10.1016/j.rgg.2016.01.008

DO - 10.1016/j.rgg.2016.01.008

M3 - Article

AN - SCOPUS:84958660748

VL - 57

SP - 111

EP - 126

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 1

ER -