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Diamond inclusions

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Garnet inclusion in the host diamond.

Diamond inclusions are the non-diamond materials that get encapsulated inside diamond during its formation process in the mantle. The trapped materials can be other minerals or fluids like water. Since diamonds have high strength and low reactivity with either the inclusion or the volcanic host rocks which carry the diamond to the Earth's surface, the diamond serves as a container that preserves the included material intact under the changing conditions from the mantle to the surface. Although diamonds can only place a lower bound on the pressure of their formation, many inclusions provide additional constraints on the pressure, temperature and even age of formation.

Inclusion types

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Types and materials of diamond inclusions (Summary)
Types Main materials
Mineral (solid) Silicates (e.g. garnet, silicate perovskites), oxides, sulfides
Fluid Fluids (containing carbonates, silicates, sulfides, halides, hydroxyl groups, etc.), water, brines
Multiphase Fluid inclusions coexisting with mineral inclusions in the same diamond

Mineral inclusions

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Main article: Inclusion (mineral)
Chromium vs. Calcium content of various inclusions. Eclogite (i.e. garnet-bearing) inclusions in diamond contain less Cr2O3 whereas peridotite (lherzolite and harzburgite) garnet inclusions have less CaO. Eclogite and peridotite are the two main parental mantle rocks and wehrlite and websterite are minor types.[1][2][3]

Mineral inclusions, especially the silicate inclusions in lithospheric diamonds, can be classified into two dominant types depending on the mantle parental rocks of the host diamond: eclogite (E-type) and peridotite (P-type). These are the two main parental rocks for the diamond formation which mostly lead to silicate inclusions.[1][4] P-type and E-type inclusions can be distinguished based on the content of specific materials in the trapped mineral. For instance, in garnet inclusions, the content ratio of chromium(III) oxide (Cr2O3) and calcium oxide (CaO) can be the basis for the classification.[5] E-type garnet inclusion contains less Cr2O3 while P-type contains less CaO. Trace elements such as rare earth elements (REE) can also characterize P-type and E-type garnet inclusions.[6] Similarly, nitrogen inclusions can be classified into P-type and E-type inclusions by analyzing their stable isotopes.[7] For sulfide inclusions, osmium contents from rhenium-osmium dating can differentiate P-type and E-type inclusions.[8]

In the cratonic crust of the Kaapvaal-Zimbabwe craton, Southern Africa, seismic velocity at 150-km depth correlates with the nature of diamond inclusions, whether peridotitic or eclogitic. This suggests that lithospheric P-wave speeds can be used, perhaps elsewhere as well as in Southern Africa, to map the distribution of different diamond source regions.[9]

Tomographic image of the lithospheric mantle obtained from the P-wave data. Red squares represent eclogitic and green squares represent peridotitic inclusions.[10][9]

Sub-lithospheric mineral inclusions such as majorite and silicate perovskites (e.g. bridgmanite, davemaoite) can be also classified into ultramafic type (peridotitic) and basaltic type (eclogitic) inclusions.[11] However, these additional classifications are harder than the lithospheric inclusions due to the rarity of samples, small grain size, and difficulties in recognizing the original mineral assemblages under deep-mantle conditions.[1]

Examples showing the imposition of the host diamond's morphology on the included mineral in syngenetic inclusions. (a) Inclusion of olivine in diamond with their faces imposed by octahedral (o) and cubic (c) shapes common in diamond. (b) Diamond with several olivine inclusions with faces parallel to the octahedral diamond face.[1][12][13]

The timing of mineral crystallization can be used to categorize diamond inclusions into three types: protogenetic, syngenetic, and epigenetic inclusions.[14] Minerals in the protogenetic inclusions were crystallized earlier than the diamond formation. The host diamond encapsulated pre-existing minerals during its crystallization. Therefore, protogenetic inclusions provide information on the conditions that existed before diamond formation. This can explain isotopically different mineral inclusions found from the same generation of diamonds.[15] For syngenetic mineral inclusions, the crystallization of the trapped mineral and the diamond occur simultaneously.[1] In this case, the environmental records from included minerals match that of the host diamond. Syngenetic inclusions can be evidenced by the imposition of host diamond morphology on the trapped mineral.[16] Epigenetic inclusions are formed from minerals that crystallized after the diamond formation. The after-formed minerals can crystallize along diamond fractures or the pre-existing protogenetic/syngenetic inclusions may have been altered into new material.[1]

Mineral inclusions can preserve materials formed under the extreme environments in Earth's mantle back to surface conditions.[1] This enables the discovery of the natural form of minerals which have previously been only synthesized in the laboratory.[17] For instance, the natural calcium silicate perovskite (CaSiO3), was recently given the mineral name davemaoite, when it was discovered as a mineral inclusion in a diamond in 2021.[18] The discovery was surprising due to the extreme conditions necessary to synthesize davemaoite which made it seem unlikely that it could be preserved at the Earth's surface.[17]

Classification of mineral inclusions (Summary)
Classification Types Etc.
Location of the inclusion - Lithospheric

- Sub-lithospheric

Parental rocks of the host diamond - P-type (peridotitic)

- E-type (eclogitic)

  • Common bases that determine P/E-types

Cr2O3/CaO content (garnet inclusion)

Osmium content (sulfide inclusion)

Stable isotope (nitrogen inclusion)

Rare-earth element content

Seismic velocity differences in P-wave

Timing of crystallization of the included mineral - Protogenetic

- Syngenetic

- Epigenetic

Fluid inclusions

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Main article: Fluid inclusion

Fluid inclusions trap fluids containing materials like silicates, carbonates and hydroxyl groups, water and brine.[19] Such fluid inclusions can be found in coated diamonds (monocrystalline diamonds coated by polycrystalline diamonds with fluid inclusions) and fibrous diamonds (diamonds coated by rods or blades of diamonds with fibrous structures).[1] Fluid microinclusions mostly contain carbonates with the silicate or halides forming the silicate-carbonate or halide-carbonate assemblages.[20] Similarly, subduction-derived saline fluids with a high concentration of K and Cl can be found from microinclusions in the cloudy diamonds (fluid-rich central fibrous diamonds transforming into fluid-poor outward diamonds).[21] Saline and silicic fluid inclusions do not co-exist, implying the immiscibility of the two fluids during the diamond formation.[22][23] The presence of volatile materials originating from subduction zones such as sulfide inclusions can suggest the viability of subduction-related crustal recycling during the diamond formation in specific continents where the diamond was created.[24]

In 2018, the high-pressure form of water known as ice-VII was found in the diamond inclusion. This discovery suggests the presence of water-rich fluids in the transition zone.[25]

Multiphase inclusions

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In the diamond-forming conditions of high pressures and temperatures, hydrous silicate melt and the aqueous fluid make a single-phase supercritical mixture. This mixture forms fibrous, cloudy, or polycrystalline diamonds with multiphase inclusions.[26] Multiphase inclusions host fluids (mainly containing carbonates and silicates, high density aqueous fluids, and brines) and the mineral inclusions in the same diamond.[27]

Research techniques

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High-resolution techniques like Fourier Transform Infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) imaging, and Electron Microprobe (EPMA) are commonly used to analyze the composition and phase of the trapped material in the diamond.[1] Non-destructive elastic methods such as micro-Raman spectroscopy, strain birefringence analysis, and single-crystal X-ray diffraction are used to estimate the pressure-temperature conditions of the material inside the diamond while minimizing the sample damage.[1]

References

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  1. ^ a b c d e f g h i j Shirey, Steven B.; Cartigny, Pierre; Frost, Daniel J.; Keshav, Shantanu; Nestola, Fabrizio; Nimis, Paolo; Pearson, D. Graham; Sobolev, Nikolai V.; Walter, Michael J. (2013-01-01). "Diamonds and the Geology of Mantle Carbon". Reviews in Mineralogy and Geochemistry. 75 (1): 355–421. Bibcode:2013RvMG...75..355S. doi:10.2138/rmg.2013.75.12. ISSN 1529-6466.
  2. ^ Stachel, T.; Harris, J. W. (2008-09-01). "The origin of cratonic diamonds — Constraints from mineral inclusions". Ore Geology Reviews. The Genesis of Gem Deposits. 34 (1): 5–32. Bibcode:2008OGRv...34....5S. doi:10.1016/j.oregeorev.2007.05.002. ISSN 0169-1368.
  3. ^ Grütter, Herman S.; Gurney, John J.; Menzies, Andrew H.; Winter, Ferdi (2004-09-01). "An updated classification scheme for mantle-derived garnet, for use by diamond explorers". Lithos. Selected Papers from the Eighth International Kimberlite Conference. Volume 2: The J. Barry Hawthorne Volume. 77 (1): 841–857. Bibcode:2004Litho..77..841G. doi:10.1016/j.lithos.2004.04.012. ISSN 0024-4937.
  4. ^ "Age, Origin, and Emplacement of Diamonds: Scientific Advances in the Last Decade | Gems & Gemology". www.gia.edu. Retrieved 2022-02-14.
  5. ^ Gurney, J. J.; Switzer, G. S. (1973-06-01). "The discovery of garnets closely related to diamonds in the Finsch pipe, South Africa". Contributions to Mineralogy and Petrology. 39 (2): 103–116. Bibcode:1973CoMP...39..103G. doi:10.1007/BF00375734. ISSN 1432-0967. S2CID 129566418.
  6. ^ Stachel, Thomas; Aulbach, Sonja; Brey, Gerhard P.; Harris, Jeff W.; Leost, Ingrid; Tappert, Ralf; Viljoen, K. S. (Fanus) (2004-09-01). "The trace element composition of silicate inclusions in diamonds: a review". Lithos. Selected Papers from the Eighth International Kimberlite Conference. Volume 2: The J. Barry Hawthorne Volume. 77 (1): 1–19. Bibcode:2004Litho..77....1S. doi:10.1016/j.lithos.2004.03.027. ISSN 0024-4937.
  7. ^ Cartigny, Pierre (2005-03-01). "Stable Isotopes and the Origin of Diamond". Elements. 1 (2): 79–84. Bibcode:2005Eleme...1...79C. doi:10.2113/gselements.1.2.79. ISSN 1811-5209.
  8. ^ Pearson, D. G.; Shirey, S. B.; Harris, J. W.; Carlson, R. W. (1998-08-01). "Sulphide inclusions in diamonds from the Koffiefontein kimberlite, S Africa: constraints on diamond ages and mantle Re–Os systematics". Earth and Planetary Science Letters. 160 (3): 311–326. Bibcode:1998E&PSL.160..311P. doi:10.1016/S0012-821X(98)00092-2. ISSN 0012-821X.
  9. ^ a b Shirey, Steven B.; Harris, Jeffrey W.; Richardson, Stephen H.; Fouch, Matthew J.; James, David E.; Cartigny, Pierre; Deines, Peter; Viljoen, Fanus (2002-09-06). "Diamond Genesis, Seismic Structure, and Evolution of the Kaapvaal-Zimbabwe Craton". Science. 297 (5587): 1683–1686. Bibcode:2002Sci...297.1683S. doi:10.1126/science.1072384. PMID 12215642. S2CID 21246590.
  10. ^ "Mineralogical Society of America - Carbon in Earth (Open Access)". www.minsocam.org. Retrieved 2022-02-18.
  11. ^ Stachel, Thomas; Brey, Gerhard P.; Harris, Jeffrey W. (2005-03-01). "Inclusions in Sublithospheric Diamonds: Glimpses of Deep Earth". Elements. 1 (2): 73–78. Bibcode:2005Eleme...1...73S. doi:10.2113/gselements.1.2.73. ISSN 1811-5209. S2CID 129249737.
  12. ^ Nestola, Fabrizio; Nimis, Paolo; Ziberna, Luca; Longo, Micaela; Marzoli, Andrea; Harris, Jeff W.; Manghnani, Murli H.; Fedortchouk, Yana (2011-05-01). "First crystal-structure determination of olivine in diamond: Composition and implications for provenance in the Earth's mantle". Earth and Planetary Science Letters. 305 (1): 249–255. Bibcode:2011E&PSL.305..249N. doi:10.1016/j.epsl.2011.03.007. ISSN 0012-821X.
  13. ^ Sobolev, NV. "Crystalline inclusions with octahedral faces in diamonds". Doklady Akademii Nauk. 204: 117.
  14. ^ Meyer, Henry O. A.; McCallum, Malcolm E. (1986). "Mineral Inclusions in Diamonds from the Sloan Kimberlites, Colorado". The Journal of Geology. 94 (4): 600–612. Bibcode:1986JG.....94..600M. doi:10.1086/629062. ISSN 0022-1376. JSTOR 30071572. S2CID 128532495.
  15. ^ Thomassot, E.; Cartigny, P.; Harris, J. W.; Lorand, J. P.; Rollion-Bard, C.; Chaussidon, M. (2009-05-30). "Metasomatic diamond growth: A multi-isotope study (13C, 15N, 33S, 34S) of sulphide inclusions and their host diamonds from Jwaneng (Botswana)". Earth and Planetary Science Letters. 282 (1): 79–90. Bibcode:2009E&PSL.282...79T. doi:10.1016/j.epsl.2009.03.001. ISSN 0012-821X.
  16. ^ J. W., Harris (1968). "Recognition of diamond inclusions. 1. Syngenetic mineral inclusions". Industrial Diamond Review. 28: 402.
  17. ^ a b Witze, Alexandra (2021-11-11). "Diamond delivers long-sought mineral from the deep Earth". Nature. doi:10.1038/d41586-021-03409-2. PMID 34764468. S2CID 244039394.
  18. ^ Tschauner, Oliver; Huang, Shichun; Yang, Shuying; Humayun, Munir; Liu, Wenjun; Corder, Stephanie N. Gilbert; Bechtel, Hans A.; Tischler, Jon; Rossman, George R. (2021-11-12). "Discovery of davemaoite, CaSiO3-perovskite, as a mineral from the lower mantle". Science. 374 (6569): 891–894. Bibcode:2021Sci...374..891T. doi:10.1126/science.abl8568. PMID 34762475. S2CID 244039905.
  19. ^ De Corte, K; Cartigny, P; Shatsky, V. S; Sobolev, N. V; Javoy, M (1998-12-01). "Evidence of fluid inclusions in metamorphic microdiamonds from the Kokchetav massif, northern Kazakhstan". Geochimica et Cosmochimica Acta. 62 (23): 3765–3773. Bibcode:1998GeCoA..62.3765D. doi:10.1016/S0016-7037(98)00266-X. ISSN 0016-7037.
  20. ^ Klein-BenDavid, Ofra; Wirth, Richard; Navon, Oded (2006-02-01). "TEM imaging and analysis of microinclusions in diamonds: A close look at diamond-growing fluids". American Mineralogist. 91 (2–3): 353–365. Bibcode:2006AmMin..91..353K. doi:10.2138/am.2006.1864. ISSN 1945-3027. S2CID 98714884.
  21. ^ Izraeli, Elad S.; Harris, Jeffrey W.; Navon, Oded (2001-05-15). "Brine inclusions in diamonds: a new upper mantle fluid". Earth and Planetary Science Letters. 187 (3): 323–332. Bibcode:2001E&PSL.187..323I. doi:10.1016/S0012-821X(01)00291-6. ISSN 0012-821X.
  22. ^ Safonov, Oleg G.; Perchuk, Leonid L.; Litvin, Yuriy A. (2007-01-15). "Melting relations in the chloride–carbonate–silicate systems at high-pressure and the model for formation of alkalic diamond–forming liquids in the upper mantle". Earth and Planetary Science Letters. 253 (1): 112–128. Bibcode:2007E&PSL.253..112S. doi:10.1016/j.epsl.2006.10.020. ISSN 0012-821X.
  23. ^ Burgess, Ray; Cartigny, Pierre; Harrison, Darrell; Hobson, Emily; Harris, Jeff (2009-03-15). "Volatile composition of microinclusions in diamonds from the Panda kimberlite, Canada: Implications for chemical and isotopic heterogeneity in the mantle". Geochimica et Cosmochimica Acta. 73 (6): 1779–1794. Bibcode:2009GeCoA..73.1779B. doi:10.1016/j.gca.2008.12.025. ISSN 0016-7037.
  24. ^ Richardson, S. H.; Shirey, S. B.; Harris, J. W.; Carlson, R. W. (2001-09-15). "Archean subduction recorded by Re–Os isotopes in eclogitic sulfide inclusions in Kimberley diamonds". Earth and Planetary Science Letters. 191 (3): 257–266. Bibcode:2001E&PSL.191..257R. doi:10.1016/S0012-821X(01)00419-8. ISSN 0012-821X.
  25. ^ Tschauner, O.; Huang, S.; Greenberg, E.; Prakapenka, V. B.; Ma, C.; Rossman, G. R.; Shen, A. H.; Zhang, D.; Newville, M.; Lanzirotti, A.; Tait, K. (2018-03-09). "Ice-VII inclusions in diamonds: Evidence for aqueous fluid in Earth's deep mantle". Science. 359 (6380): 1136–1139. Bibcode:2018Sci...359.1136T. doi:10.1126/science.aao3030. ISSN 0036-8075. PMID 29590042. S2CID 206662912.
  26. ^ Bureau, Hélène; Langenhorst, Falko; Auzende, Anne-Line; Frost, Daniel J.; Estève, Imène; Siebert, Julien (2012-01-15). "The growth of fibrous, cloudy and polycrystalline diamonds". Geochimica et Cosmochimica Acta. 77: 202–214. Bibcode:2012GeCoA..77..202B. doi:10.1016/j.gca.2011.11.016. ISSN 0016-7037. {{cite journal}}: |last1= has generic name (help)
  27. ^ Izraeli, Elad S.; Harris, Jeffrey W.; Navon, Oded (2001-05-15). "Brine inclusions in diamonds: a new upper mantle fluid". Earth and Planetary Science Letters. 187 (3): 323–332. Bibcode:2001E&PSL.187..323I. doi:10.1016/S0012-821X(01)00291-6. ISSN 0012-821X.
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