TY - JOUR
T1 - A microinclusion of lower-mantle rock and other minerals and nitrogen lower-mantle inclusions in a diamond
AU - Kaminsky, Felix V.
AU - Wirth, Richard
AU - Schreiber, Anja
PY - 2015/1/1
Y1 - 2015/1/1
N2 - A microcrystalline polymineral aggregate was identified as an inclusion in a diamond from the Rio Soriso area, Mato Grosso State, Brazil. It is composed of iron carbides, Fe-rich periclase (with exsolved magnesioferrite), and two orthorhom-bic, postspinel phases-Mg-Cr-Fe and Ca-Cr oxides, which are new mineral phases. This association was formed during several stages and may be considered as a rock microfragment from the lower mantle. In addition to the carbide-oxide fragment, other phases were identified as inclusions in the diamond, such as parascandolaite KMgF3 (that is stable at pressures of up to 50 GPa) in association with orthorhombic MgO, and porous dolomite occurring together with nanoinclusions of calcite, apatite, spinel, Fe-sulfide, and an assemblage of periclase plus wüstite. These minerals belong to the carbonatitic association and, along with syngenetic nanoinclusions of fluid nitrogen, represent the media of diamond formation. The assemblage of peri-clase and wüstite within the carbonatitic matrix points to the origin of diamond from a carbonatitic environment within the lower mantle under pressure conditions of ≥85-86 GPa (∼1,900 km depth).
AB - A microcrystalline polymineral aggregate was identified as an inclusion in a diamond from the Rio Soriso area, Mato Grosso State, Brazil. It is composed of iron carbides, Fe-rich periclase (with exsolved magnesioferrite), and two orthorhom-bic, postspinel phases-Mg-Cr-Fe and Ca-Cr oxides, which are new mineral phases. This association was formed during several stages and may be considered as a rock microfragment from the lower mantle. In addition to the carbide-oxide fragment, other phases were identified as inclusions in the diamond, such as parascandolaite KMgF3 (that is stable at pressures of up to 50 GPa) in association with orthorhombic MgO, and porous dolomite occurring together with nanoinclusions of calcite, apatite, spinel, Fe-sulfide, and an assemblage of periclase plus wüstite. These minerals belong to the carbonatitic association and, along with syngenetic nanoinclusions of fluid nitrogen, represent the media of diamond formation. The assemblage of peri-clase and wüstite within the carbonatitic matrix points to the origin of diamond from a carbonatitic environment within the lower mantle under pressure conditions of ≥85-86 GPa (∼1,900 km depth).
KW - CaCr O
KW - MgCr O
KW - Iron carbide
KW - Lower mantle
KW - Fe SiC
KW - Nitrogen
KW - Parascandolaite
KW - Wüstite
UR - http://www.scopus.com/inward/record.url?scp=84941198084&partnerID=8YFLogxK
U2 - 10.3749/canmin.1400070
DO - 10.3749/canmin.1400070
M3 - Article
AN - SCOPUS:84941198084
SN - 0008-4476
VL - 53
SP - 83
EP - 104
JO - Canadian Mineralogist
JF - Canadian Mineralogist
IS - 1
ER -