scholarly journals Diamond formation in an electric field under deep Earth conditions

2021 ◽  
Vol 7 (4) ◽  
pp. eabb4644
Author(s):  
Yuri N. Palyanov ◽  
Yuri M. Borzdov ◽  
Alexander G. Sokol ◽  
Yuliya V. Bataleva ◽  
Igor N. Kupriyanov ◽  
...  
Keyword(s):  
Electric Fields ◽  
Lithospheric Mantle ◽  
Isotope Fractionation ◽  
Diamond Formation ◽  
Mantle Minerals ◽  
Electrochemical Processes ◽  
Mantle Mineral ◽  
Deep Earth ◽  
Diamond Crystallization ◽  
Global Carbon

Most natural diamonds are formed in Earth’s lithospheric mantle; however, the exact mechanisms behind their genesis remain debated. Given the occurrence of electrochemical processes in Earth’s mantle and the high electrical conductivity of mantle melts and fluids, we have developed a model whereby localized electric fields play a central role in diamond formation. Here, we experimentally demonstrate a diamond crystallization mechanism that operates under lithospheric mantle pressure-temperature conditions (6.3 and 7.5 gigapascals; 1300° to 1600°C) through the action of an electric potential applied across carbonate or carbonate-silicate melts. In this process, the carbonate-rich melt acts as both the carbon source and the crystallization medium for diamond, which forms in assemblage with mantle minerals near the cathode. Our results clearly demonstrate that electric fields should be considered a key additional factor influencing diamond crystallization, mantle mineral–forming processes, carbon isotope fractionation, and the global carbon cycle.

Deep electrical structure of northern Alberta (Canada): implications for diamond exploration

2009 ◽  
Vol 46 (2) ◽  
pp. 139-154 ◽  
Author(s):  
Erşan Türkoğlu ◽  
Martyn Unsworth ◽  
Dinu Pana
Keyword(s):  
Subduction Zone ◽  
Upper Mantle ◽  
Lithospheric Mantle ◽  
Three Dimensional ◽  
Diamond Formation ◽  
Magnetotelluric Data ◽  
Diamond Exploration ◽  
Upper Mantle Structure ◽  
Resistivity Model ◽  
Northern Alberta

Geophysical studies of upper mantle structure can provide constraints on diamond formation. Teleseismic and magnetotelluric data can be used in diamond exploration by mapping the depth of the lithosphere–asthenosphere boundary. Studies in the central Slave Craton and at Fort-à-la-Corne have detected conductors in the lithospheric mantle close to, or beneath, diamondiferous kimberlites. Graphite can potentially explain the enhanced conductivity and may imply the presence of diamonds at greater depth. Petrologic arguments suggest that the shallow lithospheric mantle may be too oxidized to contain graphite. Other diamond-bearing regions show no upper mantle conductor suggesting that the correlation with diamondiferous kimberlites is not universal. The Buffalo Head Hills in Alberta host diamondiferous kimberlites in a Proterozoic terrane and may have formed in a subduction zone setting. Long period magnetotelluric data were used to investigate the upper mantle resistivity structure of this region. Magnetotelluric (MT) data were recorded at 23 locations on a north–south profile extending from Fort Vermilion to Utikuma Lake and an east–west profile at 57.2°N. The data were combined with Lithoprobe MT data and inverted to produce a three-dimensional (3-D) resistivity model with the asthenosphere at 180–220 km depth. This model did not contain an upper mantle conductor beneath the Buffalo Head Hills kimberlites. The 3-D inversion exhibited an eastward dipping conductor in the crust beneath the Kiskatinaw terrane that could represent the fossil subduction zone that supplied the carbon for diamond formation. The low resistivity at crustal depths in this structure is likely due to graphite derived from subducted organic material.

scholarly journals Xenon iron oxides predicted as potential Xe hosts in Earth’s lower mantle

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Feng Peng ◽  
Xianqi Song ◽  
Chang Liu ◽  
Quan Li ◽  
Maosheng Miao ◽  
...  
Keyword(s):  
Iron Oxides ◽  
Lower Mantle ◽  
Search Algorithm ◽  
Mass Density ◽  
Mantle Minerals ◽  
Fe Oxides ◽  
Structure Search ◽  
Wide Range ◽  
Deep Earth ◽  
Calculated Mass

Abstract An enduring geological mystery concerns the missing xenon problem, referring to the abnormally low concentration of xenon compared to other noble gases in Earth’s atmosphere. Identifying mantle minerals that can capture and stabilize xenon has been a great challenge in materials physics and xenon chemistry. Here, using an advanced crystal structure search algorithm in conjunction with first-principles calculations we find reactions of xenon with recently discovered iron peroxide FeO2, forming robust xenon-iron oxides Xe2FeO2 and XeFe3O6 with significant Xe-O bonding in a wide range of pressure-temperature conditions corresponding to vast regions in Earth’s lower mantle. Calculated mass density and sound velocities validate Xe-Fe oxides as viable lower-mantle constituents. Meanwhile, Fe oxides do not react with Kr, Ar and Ne. It means that if Xe exists in the lower mantle at the same pressures as FeO2, xenon-iron oxides are predicted as potential Xe hosts in Earth’s lower mantle and could provide the repository for the atmosphere’s missing Xe. These findings establish robust materials basis, formation mechanism, and geological viability of these Xe-Fe oxides, which advance fundamental knowledge for understanding xenon chemistry and physics mechanisms for the possible deep-Earth Xe reservoir.

Iron carbide as a source of carbon for graphite and diamond formation under lithospheric mantle P-T parameters

Lithos ◽  
2017 ◽  
Vol 286-287 ◽  
pp. 151-161 ◽  
Author(s):  
Yuliya V. Bataleva ◽  
Yuri N. Palyanov ◽  
Yuri M. Borzdov ◽  
Oleg A. Bayukov ◽  
Evgeniy V. Zdrokov
Keyword(s):  
Lithospheric Mantle ◽  
Iron Carbide ◽  
Diamond Formation

scholarly journals Insensitivity of alkenone carbon isotopes to atmospheric CO<sub>2</sub> at low to moderate CO<sub>2</sub> levels

2018 ◽  
Author(s):  
Marcus P. S. Badger ◽  
Thomas B. Chalk ◽  
Gavin L. Foster ◽  
Paul R. Bown ◽  
Samantha J. Gibbs ◽  
...  
Keyword(s):  
Isotope Fractionation ◽  
Isotope Composition ◽  
Ice Core ◽  
Co2 Uptake ◽  
Geological Time ◽  
Time Intervals ◽  
The Past ◽  
The Earth ◽  
Global Carbon ◽  
Carbon System

Abstract. Atmospheric pCO2 is a critical component of the global carbon system and is considered to be the major control of Earth's past, present and future climate. Accurate and precise reconstructions of its concentration through geological time are, therefore, crucial to our understanding of the Earth system. Ice core records document pCO2 for the past 800 kyrs, but at no point during this interval were CO2 levels higher than today. Interpretation of older pCO2 has been hampered by discrepancies during some time intervals between two of the main ocean-based proxy methods used to reconstruct pCO2: the carbon isotope fractionation that occurs during photosynthesis as recorded by haptophyte biomarkers (alkenones) and the boron isotope composition (δ11B) of foraminifer shells. Here we present alkenone and δ11B-based pCO2 reconstructions generated from the same samples from the Plio-Pleistocene at ODP Site 999 across a glacial-interglacial cycle. We find a muted response to pCO2 in the alkenone record compared to contemporaneous ice core and δ11B records, suggesting caution in the interpretation of alkenone-based records at low pCO2 levels. This is possibly caused by the physiology of CO2 uptake in the haptophytes. Our new understanding resolves some of the inconsistencies between the proxies and highlights that caution may be required when interpreting alkenone-based reconstructions of pCO2.

scholarly journals The South India Precambrian crust and shallow lithospheric mantle: Initial results from the India Deep Earth Imaging Experiment (INDEX)

2013 ◽  
Vol 122 (6) ◽  
pp. 1435-1453 ◽  
Author(s):  
S S RAI ◽  
KAJALJYOTI BORAH ◽  
RITIMA DAS ◽  
SANDEEP GUPTA ◽  
SHALIVAHAN SRIVASTAVA ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
South India ◽  
The South ◽  
Imaging Experiment ◽  
Deep Earth ◽  
Initial Results

Oxygen isotope fractionation in mantle minerals

1998 ◽  
Vol 41 (1) ◽  
pp. 95-103 ◽  
Author(s):  
Yongfei Zheng ◽  
Chunsheng Wei ◽  
Gentao Zhou ◽  
Baolong Xu
Keyword(s):  
Oxygen Isotope ◽  
Isotope Fractionation ◽  
Oxygen Isotope Fractionation ◽  
Mantle Minerals

Isotope fractionation of carbon during diamond crystallization in model systems

2015 ◽  
Vol 56 (1-2) ◽  
pp. 239-244 ◽  
Author(s):  
V.N. Reutsky ◽  
Yu.N. Palyanov ◽  
Yu.M. Borzdov ◽  
A.G. Sokol
Keyword(s):  
Isotope Fractionation ◽  
Model Systems ◽  
Diamond Crystallization

scholarly journals Composition of spherules and lower mantle minerals, isotopic and geochemical characteristics of zircon from volcaniclastic facies of the Mriya lamproite pipe

2020 ◽  
Vol 242 ◽  
pp. 150
Author(s):  
Ivan YATSENKO ◽  
Sergey SKUBLOV ◽  
Ekaterina LEVASHOVA ◽  
Olga GALANKINA ◽  
Sergey BEKESHA
Keyword(s):  
Intermetallic Alloys ◽  
Primary Metal ◽  
Mantle Minerals ◽  
Basement Rocks ◽  
Reducing Conditions ◽  
Mantle Mineral ◽  
Geochemical Study ◽  
Metal Silicate ◽  
Volcaniclastic Rocks ◽  
Different Sources

The article presents the results of studying the rocks of the pyroclastic facies of the Mriya lamproite pipe, located on the Priazovsky block of the Ukrainian shield. In them the rock's mineral composition includes a complex of exotic mineral particles formed under extreme reduction mantle conditions: silicate spherules, particles of native metals and intermetallic alloys, oxygen-free minerals such as diamond, qusongite (WC), and osbornite (TiN). The aim of the research is to establish the genesis of volcaniclastic rocks and to develop ideas of the highly deoxidized mantle mineral association (HRMMA), as well as to conduct an isotopic and geochemical study of zircon. As a result, groups of minerals from different sources are identified in the heavy fraction: HRMMA can be attributed to the juvenile magmatic component of volcaniclastic rocks; a group of minerals and xenoliths that can be interpreted as xenogenic random material associated with mantle nodules destruction (hornblendite, olivinite and dunite xenoliths), intrusive lamproites (tremolite-hornblende) and crystalline basement rocks (zircon, hornblende, epidote, and granitic xenoliths). The studied volcaniclastic rocks can be defined as intrusive pyroclastic facies (tuffisites) formed after the lamproites intrusion. Obviously, the HRMMA components formed under extreme reducing conditions at high temperatures, which are characteristic of the transition core-mantle zone. Thus, we believe that the formation of primary metal-silicate HRMMA melts is associated with the transition zone D".

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