A genetic metasomatic link between eclogitic and peridotitic diamond inclusions

Mikhail, Sami; Rinaldi, Michele; Mare, Eleanor Rose; Sverjensky, Dimitri A.

doi:10.7185/geochemlet.2111

Cited by 9 publications

(1 citation statement)

References 26 publications

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“…This does not necessarily mean that these diamonds formed at great depths, ascending through the mantle in a plume and then grew again at shallower depths through different processes and under different conditions. The observed chemical disequilibrium may rather reflect progressive chemical mass transfer during a reaction between a fluid released by a deeply subducted mafic slab with ambient peridotite [35,38].…”

Section: Discussionmentioning

confidence: 99%

Distinct Groups of Low- and High-Fe Ferropericlase Inclusions in Super-Deep Diamonds: An Example from the Juina Area, Brazil

Kaminsky,

Zedgenizov,

Sevastyanov

et al. 2023

Minerals

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Diamonds from the Rio Sorriso placer in the Juina area, Mato Grosso State, Brazil, contain mineral inclusions of ferropericlase associated with MgSiO3, CaSiO3, magnesite, merrillite, and other minerals. The ferropericlase inclusions in Rio Sorriso diamonds are resolved into two distinct genetic and compositional groups: (1) protogenetic, high-Ni and low-Fe (Ni = 8270–10,660 ppm; mg# = 0.756–0.842) ferropericlases, and (2) syngenetic, low-Ni and high-Fe (Ni = 600–3050 ppm; mg# = 0.477–0.718) ferropericlases. Based on the crystallographic orientation relationships between natural ferropericlase inclusions and host diamonds, high-Ni and low-Fe ferropericlases originate in the upper part of the lower mantle, while low-Ni and high-Fe ferropericlases, most likely, originate in the lithosphere. Mineral inclusions form the ultramafic lower-mantle (MgSiO3, which we suggest as bridgmanite, CaSiO3, which we suggest as CaSi-perovskite, and high-Ni and low-Fe ferropericlase) and lithospheric (CaSiO3, which we suggest as breyite, Ca(Si,Ti)O3, and low-Ni and high-Fe ferropericlase) associations. The presence of magnesite and merrillite inclusions in association with ferropericlase confirmed the existence of a deep-seated carbonatitic association. Diamonds hosting high-Ni and low-Ni ferropericlase have different carbon-isotopic compositions (δ13C = −5.52 ± 0.75‰ versus −7.07 ± 1.23‰ VPDB, respectively). It implies the carbon-isotopic stratification of the mantle: in the lower mantle, the carbon-isotopic composition tends to become isotopically heavier (less depleted in 13C) than in lithospheric diamonds. These regularities may characterize deep-seated diamonds and ferropericlases not only in the Juina area of Brazil but also in other parts of the world.

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Section: Discussionmentioning

confidence: 99%

Distinct Groups of Low- and High-Fe Ferropericlase Inclusions in Super-Deep Diamonds: An Example from the Juina Area, Brazil

Kaminsky,

Zedgenizov,

Sevastyanov

et al. 2023

Minerals

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Imperfections in natural diamond: the key to understanding diamond genesis and the mantle

Day,

Pamato,

Novella

et al. 2023

Riv. Nuovo Cim.

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Diamond has unique physical, thermal, electrical, and optical properties with respect to other minerals and related synthetic compounds that make it extremely valuable from an economic and industrial perspective. Natural diamond that forms in the upper mantle, transition zone, and lower mantle may encapsulate mantle minerals during growth and protect them from physical breakdown and chemical alteration upon ascent of the diamond to the surface via kimberlite eruption. Such mineral inclusions serve as the only direct means to study the deep Earth and provide critical information about the pressure, temperature, and redox conditions and the chemical and isotopic composition of the mantle. Natural diamonds show a wide range of ages and thus allow one to reconstruct the history of large-scale Earth processes, such as the formation and amalgamation of Earth’s lithosphere, the onset and evolution of tectonic processes (e.g., Wilson cycles), and the recycling of C, H, and N between different primordial and crustal reservoirs. In this review, a detailed description of all types of imperfections (e.g., mineral and fluid inclusions and structural defects) and the methods by which such imperfections can be analyzed to elucidate aspects of Earth’s complex geologic history is given.

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