TY - JOUR

T1 - A mantle origin for sulfates in the unusual "salty" Udachnaya-East kimberlite from sulfur abundances, speciation and their relationship with groundmass carbonates

AU - D'Eyrames, Elisabeth

AU - Thomassot, Emilie

AU - Kitayama, Yumi

AU - Golovin, Alexander

AU - Korsakov, Andrey

AU - Ionov, Dmitri

PY - 2017/1/1

Y1 - 2017/1/1

N2 - The Udachnaya-East pipe in Yakutia in Siberia hosts a unique dry (serpentine-free) body of hypabyssal kimberlite (<0.64wt% H2O), associated with a less dry type of kimberlite and a serpentinized kimberlitic breccia. The dry kimberlite is anomalously rich in salts (Na2O and Cl both up to 6wt%) whereas the slightly less dry and the breccia kimberlite are salt free. Yet the Udachnaya kimberlite is a group-1 kimberlite, as is the archetypical kimberlite from Kimberley, South Africa. Samples were studied from the three different types of kimberlite (dry-salty, n=8, non-salty, n=5 and breccia, n=3) regarding their mineralogy, geochemistry, and more specifically their sulfur content. Our results show the salty kimberlite is unprecedentedly rich in sulfur (0.13-0.57wt%) compared to the non-salty kimberlite (0.04-0.12wt%) and the breccia (0.29-0.33wt%). In the salty kimberlite, most of the sulfur is present as sulfates (up to 97% of Stotal) and is disseminated throughout the groundmass in close association with Na-K-bearing carbonates. Sulfates occur within the crystal structure of these Na-K-bearing carbonates as the replacement of (CO3) by (SO3) groups, or as Na- and K-rich sulfates (e.g. aphtitalite, (K,Na)3Na(SO4)2). The associated sulfides are djerfisherite; also Na- and K-rich species. The close association of sulfates and carbonates in these S-rich alkaline rocks suggests that the sulfates crystallized from a mantle-derived magma, a case that has strong implication for the oxygen fugacity of kimberlite magmatism and more generally for the global S budget of the mantle.

AB - The Udachnaya-East pipe in Yakutia in Siberia hosts a unique dry (serpentine-free) body of hypabyssal kimberlite (<0.64wt% H2O), associated with a less dry type of kimberlite and a serpentinized kimberlitic breccia. The dry kimberlite is anomalously rich in salts (Na2O and Cl both up to 6wt%) whereas the slightly less dry and the breccia kimberlite are salt free. Yet the Udachnaya kimberlite is a group-1 kimberlite, as is the archetypical kimberlite from Kimberley, South Africa. Samples were studied from the three different types of kimberlite (dry-salty, n=8, non-salty, n=5 and breccia, n=3) regarding their mineralogy, geochemistry, and more specifically their sulfur content. Our results show the salty kimberlite is unprecedentedly rich in sulfur (0.13-0.57wt%) compared to the non-salty kimberlite (0.04-0.12wt%) and the breccia (0.29-0.33wt%). In the salty kimberlite, most of the sulfur is present as sulfates (up to 97% of Stotal) and is disseminated throughout the groundmass in close association with Na-K-bearing carbonates. Sulfates occur within the crystal structure of these Na-K-bearing carbonates as the replacement of (CO3) by (SO3) groups, or as Na- and K-rich sulfates (e.g. aphtitalite, (K,Na)3Na(SO4)2). The associated sulfides are djerfisherite; also Na- and K-rich species. The close association of sulfates and carbonates in these S-rich alkaline rocks suggests that the sulfates crystallized from a mantle-derived magma, a case that has strong implication for the oxygen fugacity of kimberlite magmatism and more generally for the global S budget of the mantle.

KW - Kimberlite

KW - Mantle

KW - Siberia

KW - Sulfates

KW - Sulfides

KW - Udachnaya

KW - SOUTH-AFRICA

KW - PETROGENESIS

KW - YAKUTIA

KW - ALKALI CHLORIDES

KW - UNALTERED KIMBERLITES

KW - PIPE

KW - GROUP-I

KW - MELT INCLUSIONS

KW - RUSSIA

KW - MAGMA EVOLUTION

UR - http://www.scopus.com/inward/record.url?scp=85026663687&partnerID=8YFLogxK

U2 - 10.1051/bsgf/2017007

DO - 10.1051/bsgf/2017007

M3 - Article

AN - SCOPUS:85026663687

VL - 188

JO - Bulletin - Societie Geologique de France

JF - Bulletin - Societie Geologique de France

SN - 0037-9409

IS - 1-2

M1 - 6

ER -