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The Sheahan Diamond Literature Reference Compilation - Scientific and Media Articles based on Major Keyword - Chemistry
The Sheahan Diamond Literature Reference Compilation is compiled by Patricia Sheahan who publishes on a monthly basis a list of new scientific articles related to diamonds as well as media coverage and corporate announcements called the Sheahan Diamond Literature Service that is distributed as a free pdf to a list of followers. Pat has kindly agreed to allow her work to be made available as an online digital resource at Kaiser Research Online so that a broader community interested in diamonds and related geology can benefit. The references are for personal use information purposes only; when available a link is provided to an online location where the full article can be accessed or purchased directly. Reproduction of this compilation in part or in whole without permission from the Sheahan Diamond Literature Service is strictly prohibited. Return to Diamond Keyword Index
Sheahan Diamond Literature Reference Compilation - Scientific Articles by Author for all years
Each article reference in the SDLRC is tagged with one or more key words assigned by Pat Sheahan to highlight the main topics of the article. In an effort to make it easier for users to track down articles related to a specific topic, KRO has extracted these key words and developed a list of major key words presented in this Key Word Index to which individual key words used in the article reference have been assigned. In most of the individual Key Word Reports the references are in crhonological order, though in some such as Deposits the order is first by key word and then chronological. Only articles classified as "technical" (mainly scientific journal articles) and "media" (independent media articles) are included in the Key Word Index. References that were added in the most recent monthly update are highlighted in yellow.
Chemistry is a very generic term that encompasses all sorts of topics but the main one relevant to diamonds is what is called "inclusion chemistry", namely the chemical composition of minerals that form within a diamond at the same time as the diamond is forming in the mantle. Diamonds form within a precise range of pressure-temperature combinations. Other minerals such as garnets form not just within this range but beyond this range. A kimberlite magma entrains rocks encountered during its ascent and gradually disaggregates them so that individual crystals consisting of garnets, diamonds, and chromites end up distributed randomly within the kimberlitic magma. Inclusion chemistry is directed at determining whether or not rocks harvested during the magma's ascent are potential diamond bearing rocks. The trick is to identify those minerals which form exclusively within the PT range that supports diamond formation. If these are detected in a kimberlite sample or in till containing material a glacier scraped from an exposed kimberlite pipe or dyke, then the probability is high that the kimberlite source also contains diamonds. Articles about chemistry tend to focus on defining those relative compositions of the elements that make up the minerals that have been found inside diamonds. The term "diamond indicator minerals" refers to those minerals which have a formation range within the diamond stability field. Since all the minerals within a kimberlite are sourced from the mantle, but not all material is from the diamond stability field, it is possible to identify that subset, particularly in the case of garnets, which only shows up in diamondiferous kimberlites, as well as that set which only shows up in a kimberlite as compared to minerals formed under lower pressure conditions near the earth's surface such as almandine garnets. The broader term "kimberlite indicator minerals" is used to establish the "chemical" signature of a kimberlite and as an exploration tool.
Ultramafic Xenoliths from Lake Bulletinen Merri and Mt. Leura, South East Australia, and Their Bearing on the Evolution of The Continental Upper Mantle.
Proceedings of Third International Kimberlite Conference, TERRA COGNITA, ABSTRACT VOLUME., Vol. 2, No. 3, P. 230, (abstract.).
Relative depletion of niobium in some arc magmas and the continental crust:partitioning of K, Nb, La, and Ce during melt/rock reaction in the uppermantle
Earth and Planetary Science Letters, Vol. 120, No. 3/4 December pp. 111-134
Mantle
Melt rock interaction, potassium, lanthanum, cerium
Natarajam, R., Savitha, G., Dominiak, P., Wozniak, K., Moorthy, J.N.
Corundum, diamond and PtS metal organic frameworks with a difference: self assembly of a unique pair of 3-connecting D2d symmetric 3,3',5,5' tetrakis(4-pyridyl)bimesity1.
Angewandie Chemie, Vol. 44, 14, March 29, pp. 2115-2119.
Dongre, A., Kamde, G., Chalapathi Rao, N.V., Kale, H.S.
Is megacrystic/xenocrystic ilmenite entrainment in the source magma responsible for the non-Diamondiferous nature of the Maddur-Kotakonda-Narayanpet kimberlites
Geological Society of India, Bangalore November Meeting Group Discussion on Kimberlites and Related Rocks India, Abstract p. 72.
An AEM study of garnet clinopyroxenite from the Sulu ultrahigh pressure terrane: formation mechanisms of oriented ilmenite, spinel, magnetite, amphibole garnet
Contributions to Mineralogy and Petrology, Vol. 161, 6, pp. 901-920.
Abstract: Diamonds from the Machado River alluvial deposit have been characterised on the basis of external morphology, internal textures, carbon isotopic composition, nitrogen concentration and aggregation state and mineral inclusion chemistry. Variations in morphology and features of abrasion suggest some diamonds have been derived directly from local kimberlites, whereas others have been through extensive sedimentary recycling. On the basis of mineral inclusion compositions, both lithospheric and sublithospheric diamonds are present at the deposit. The lithospheric diamonds have clear layer-by-layer octahedral and/or cuboid internal growth zonation, contain measurable nitrogen and indicate a heterogeneous lithospheric mantle beneath the region. The sublithospheric diamonds show a lack of regular sharp zonation, do not contain detectable nitrogen, are isotopically heavy (?13CPDB predominantly ? 0.7 to ? 5.5) and contain inclusions of ferropericlase, former bridgmanite, majoritic garnet and former CaSiO3-perovskite. This suggests source lithologies that are Mg- and Ca-rich, probably including carbonates and serpentinites, subducted to lower mantle depths. The studied suite of sublithospheric diamonds has many similarities to the alluvial diamonds from Kankan, Guinea, but has more extreme variations in mineral inclusion chemistry. Of all superdeep diamond suites yet discovered, Machado River represents an end-member in terms of either the compositional range of materials being subducted to Transition Zone and lower mantle or the process by which materials are transferred from the subducted slab to the diamond-forming region.
Earth and Planetary Science Letters, Vol. 467, pp. 99-107.
Mantle
chlorine
Abstract: We report concentrations of Chlorine (Cl) in synthetic wadsleyite (Wd) and ringwoodite (Rw) in the system NaCl-(Mg,?Fe)2SiO4 under hydrous and anhydrous conditions. Multi-anvil press experiments were performed under pressures (14-22 GPa) and temperatures (1100-1400?°C) relevant to the transition zone (TZ: 410-670 km depth). Cl and H contents were measured using Particle Induced X-ray Emission (PIXE) and Elastic Recoil Detection Analysis (ERDA) respectively. Results show that Cl content in Rw and Wd is significantly higher than in other nominally anhydrous minerals from the upper mantle (olivine, pyroxene, garnet), with up to 490 ppm Cl in anhydrous Rw, and from 174 to 200 ppm Cl in hydrous Wd and up to 113 ppm Cl in hydrous Rw. These results put constrains on the Cl budget of the deep Earth. Based on these results, we propose that the TZ may be a major repository for major halogen elements in the mantle, where Cl may be concentrated together with H2OH2O and F (see Roberge et al., 2015). Assuming a continuous supply by subduction and a water-rich TZ, we use the concentrations measured in Wd (174 ppm Cl) and in Rw (106 ppm Cl) and we obtain a maximum value for the Cl budget for the bulk silicate Earth (BSE) of 15.1 × 1022 g Cl, equivalent to 37 ppm Cl. This value is larger than the 17 ppm Cl proposed previously by McDonough and Sun (1995) and evidences that the Cl content of the mantle may be higher than previously thought. Comparison of the present results with the budget calculated for F (Roberge et al., 2015) shows that while both elements abundances are probably underestimated for the bulk silicate Earth, their relative abundances are preserved. The BSE is too rich in F with respect to heavy halogen elements to be compatible with a primordial origin from chondrites CI-like (carbonaceous chondrites CC) material only. We thus propose a combination of two processes to explain these relative abundances: a primordial contribution of different chondritic-like materials, including EC-like (enstatite chondrites), possibly followed by a distinct fractionation of F during the Earth differentiation due to its lithophile behavior compared to Cl, Br and I.
Abstract: Scientists at ANU have produced the best estimate of Earth's elemental composition which will help them understand how the Earth formed 4.6 billion years ago. The Solar System began as a dense blob in a molecular cloud of hydrogen gas and dust that collapsed under its own gravity, forming the early Sun, Earth and other planets. Co-researcher Associate Professor Charley Lineweaver said the Earth's chemical composition was set at that early stage of formation. "The four most abundant elements - iron, oxygen, silicon and magnesium - make up more than 90 per cent of the Earth's mass, but working out exactly what the Earth is made of is tricky," said Dr Lineweaver from the Research School of Earth Sciences and the Research School of Astronomy and Astrophysics at ANU. "Seismological studies of earthquakes inform us about the Earth's core, mantle and crust, but it's hard to convert this information into an elemental composition. "Our deepest drilling has only scratched the surface down to 10 kilometres of our 6,400 kilometre radius planet. Rocks at the surface only come from as deep as the upper mantle." The research is published in the international journal Icarus and is available here. Lead author ANU PhD scholar Haiyang Wang said the team made the most comprehensive estimates of the Earth's composition based on a meta-analysis of previous estimates of the mantle and core, and a new estimate of the core's mass. "Our work focused on getting realistic uncertainties so that our reference model can be used in future comparisons of the Earth with the Sun, or with Mars or with any other body in the Solar System," said Mr Wang from the ANU Research School of Astronomy and Astrophysics. Co-researcher Professor Trevor Ireland from the ANU Research School of Earth Sciences said planetary scientists would find many uses for this new composition record. "This will have far-reaching importance, not only for planetary bodies in our Solar System but also other star systems in the universe," he said.
Abstract: To first order, the Earth as well as other rocky planets in the Solar System and rocky exoplanets orbiting other stars, are refractory pieces of the stellar nebula out of which they formed. To estimate the chemical composition of rocky exoplanets based on their stellar hosts' elemental abundances, we need a better understanding of the devolatilization that produced the Earth. To quantify the chemical relationships between the Earth, the Sun and other bodies in the Solar System, the elemental abundances of the bulk Earth are required. The key to comparing Earth's composition with those of other objects is to have a determination of the bulk composition with an appropriate estimate of uncertainties. Here we present concordance estimates (with uncertainties) of the elemental abundances of the bulk Earth, which can be used in such studies. First we compile, combine and renormalize a large set of heterogeneous literature values of the primitive mantle (PM) and of the core. We then integrate standard radial density profiles of the Earth and renormalize them to the current best estimate for the mass of the Earth. Using estimates of the uncertainties in i) the density profiles, ii) the core-mantle boundary and iii) the inner core boundary, we employ standard error propagation to obtain a core mass fraction of 32.5±0.3 wt%. Our bulk Earth abundances are the weighted sum of our concordance core abundances and concordance PM abundances. Our concordance estimates for the abundances of Mg, Sn, Br, B, Cd and Be are significantly lower than previous estimates of the bulk Earth. Our concordance estimates for the abundances of Na, K, Cl, Zn, Sr, F, Ga, Rb, Nb, Gd, Ta, He, Ar, and Kr are significantly higher. The uncertainties on our elemental abundances usefully calibrate the unresolved discrepancies between standard Earth models under various geochemical and geophysical assumptions.
Abstract: The subcontinental lithospheric mantle (SCLM) constitutes a significant portion of the upper mantle sourcing magmatic volatiles to the continents above, yet its geochemical signature and evolution remain poorly constrained. Here we present new interpretation of noble gas datasets from two magmatic CO2 fields in the SW US, namely Bravo Dome and Sheep Mountain, which provide a unique insight into the volatile character of the SCLM sourcing the Cenozoic volcanism in the region. We identify that reduction of 3He/4Hemantle ratio within the Sheep Mountain CO2 field can be attributed to radiogenic production within the SCLM. Using a Reduced Chi-Squared minimisation on the variation of derived 4He/21Necrust ratios within samples from the Sheep Mountain field, combined with a radiogenically raised 21Ne/22Nemantle end member, we resolve 3He/4Hemantle ratios of 2.59 ± 0.15 to 3.00 ± 0.18 Ra. These values correspond with a 21Ne/22Nemantle value of 0.136. Using these 3He/4Hemantle end member values with 21Nemantle resolved from Ne three component analysis, we derive the elemental 3He/22Nemantle of 2.80 ± 0.16 and radiogenic 4He/21Ne*mantle range of 1.11 ± 0.11 to 1.30 ± 0.14. A second Reduced Chi-Squared minimisation performed on the variation of 21Ne/40Arcrust ratios has allowed us to also determine both the 4He/40Armantle range of 0.78 to 1.21 and 21Ne/40Armantle of 7.66 ± 1.62 to 7.70 ± 1.54 within the field. Combining these ratios with the known mantle production ranges for 4He/21Ne and 4He/40Ar allows resolution of the radiogenic He/Ne and He/Ar ratios corresponding to the radiogenically lowered 3He/4Hemantle ratios. Comparing these values with those resolved from the Bravo Dome field allows identification of a clear and coherent depletion of He to Ne and He to Ar in both datasets. This depletion can only be explained by partial degassing of small melt fractions of asthenospheric melts that have been emplaced into the SCLM. This is the first time that it has been possible to resolve and account for both the mantle He/Ne and He/Ar ratios within a SCLM source. The data additionally rule out the involvement of a plume component in the mantle source of the two gas fields and hence any plume influence on the Colorado Plateau Uplift event.
