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Author: Grafiati

Published: 10 December 2022

Last updated: 28 January 2023

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1

WHITE, J. L., R. S. J. SPARKS, K. BAILEY, W. P. BARNETT, M. FIELD, and L. WINDSOR. "KIMBERLITE SILLS AND DYKES ASSOCIATED WITH THE WESSELTON KIMBERLITE PIPE, KIMBERLEY, SOUTH AFRICA." South African Journal of Geology 115, no. 1 (February 23, 2012): 1–32. http://dx.doi.org/10.2113/gssajg.115.1.1.

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2

Mitchell, Roger H., E. Michael W. Skinner, and Barbara H. Scott Smith. "Tuffisitic kimberlites from the Wesselton Mine, South Africa: Mineralogical characteristics relevant to their formation." Lithos 112 (November 2009): 452–64. http://dx.doi.org/10.1016/j.lithos.2009.06.018.

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3

Griffin, W. L., S. R. Shee, C. G. Ryan, T. T. Win, and B. A. Wyatt. "Harzburgite to lherzolite and back again: metasomatic processes in ultramafic xenoliths from the Wesselton kimberlite, Kimberley, South Africa." Contributions to Mineralogy and Petrology 134, no. 2-3 (February 1999): 232–50. http://dx.doi.org/10.1007/s004100050481.

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4

McCammon, C. A. "Oxidation during metasomatism in ultramafic xenoliths from the Wesselton kimberlite, South Africa: implications for the survival of diamond." Contributions to Mineralogy and Petrology 141, no. 3 (June 2001): 287–96. http://dx.doi.org/10.1007/s004100100244.

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5

Hanger, Brendan J., Gregory M. Yaxley, Andrew J. Berry, and Vadim S. Kamenetsky. "Relationships between oxygen fugacity and metasomatism in the Kaapvaal subcratonic mantle, represented by garnet peridotite xenoliths in the Wesselton kimberlite, South Africa." Lithos 212-215 (January 2015): 443–52. http://dx.doi.org/10.1016/j.lithos.2014.09.030.

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6

Antao, Sytle M. "Crystal Structure of an Anisotropic Pyrope Garnet That Contains Two Cubic Phases." Minerals 11, no. 12 (November 26, 2021): 1320. http://dx.doi.org/10.3390/min11121320.

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The crystal structure of two different samples of pyrope garnet, ideally Mg3Al2Si3O12, from South Africa was refined using the Rietveld method, space group Ia3¯d, and monochromatic synchrotron high-resolution powder X-ray diffraction (HRPXRD) data. Sample 1 from Wesselton Mine is a single cubic phase and is optically isotropic. Electron-probe microanalysis (EPMA) provided an average composition {Mg2.30Fe2+0.26Ca0.42Mn2+0.02}∑3[Al1.53Fe3+0.06Cr3+0.40Ti4+0.01Fe2+0.01]∑2Si3O12, which contains a significant amount of Cr cations. The unit-cell parameter (Å) and bond distances (Å) are a = 11.56197(1) Å, average <Mg-O> = 2.2985, Al-O = 1.9101(4), and Si-O = 1.6343(3) Å. Sample 2 from De Beers Diamond Mine has an average composition {Mg2.33Fe2+0.33Ca0.33Mn2+0.01}∑3[Al1.73Fe3+0.12Cr3+0.06Ti4+0.05Fe2+0.05]∑2Si3O12 and is a fine-scale intergrowth of two cubic phases. The weight percentage, unit-cell parameter (Å), and bond distances (Å) for phase 2a are 62.2(1)%, a = 11.56185(1) Å, average <Mg-O> = 2.3006, Al-O = 1.9080(4), Si-O = 1.6334(4) Å. The corresponding values for phase 2b are 37.8(1)%, a = 11.53896(1) Å, average <Mg-O> = 2.2954, Al-O = 1.9020(6), Si-O = 1.6334(6) Å. The two cubic phases in sample 2 cause the crystal to be optically anisotropic because of strain induce birefringence. The unit-cell parameter and bond distances for sample 1 are similar to those in phase 2a.

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7

Smith, C. B., H. L. Allsopp, O. G. Garvie, J. D. Kramers, P. F. S. Jackson, and C. R. Clement. "Note on the UPb perovskite method for dating kimberlites: Examples from the Wesselton and De Beers mines, South Africa, and Somerset Island, Canada." Chemical Geology: Isotope Geoscience section 79, no. 2 (August 1989): 137–45. http://dx.doi.org/10.1016/0168-9622(89)90016-x.

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8

Mokgakane, Thabile Joyce, Victor Mlambo, Khuliso Emmanuel Ravhuhali, and Norman Magoro. "Contribution of Soil Type to Quantity and Nutritional Value of Grass Species on the South African Highveld." Resources 10, no. 10 (October 18, 2021): 106. http://dx.doi.org/10.3390/resources10100106.

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The biggest threat to cattle production in most South African communal areas is poor management of grazing, which negatively affects vegetation and soil structures. This study was conducted to assess the spatial variation of grass species density, production potential and quality in Breyten (Hutton soil type), Davel (Avalon soil type), and Wesselton (Clovelly soil type) communal rangelands in the highveld region of Mpumalanga province. Three 100 m transects per grazing area, placed at 50 m intervals (0, 50, and 100 m) were used to collect soil samples at 200 mm depth. A 100 m permanent line point method, replicated three times (50 m apart) per site, was used to identify and collect grass species samples. Grass species were classified according to life form, palatability, ecological status, and abundance. Grasses species were also harvested for chemical composition and in vitro ruminal dry matter degradability determination. Soils from the study areas had an acidic pH range (3.5–4.5). Hutton soil had the highest (p < 0.05) nitrate (N-NO3) concentration (0.770 mg/kg) compared to Clovelly (0.030 mg/kg) and Avalon (0.533 mg/kg) soil types. Thirty-one grass species composed of 28 turf perennials, two weak perennials and one perennial creeping grass were identified across the study areas. About 16% of identified grass species were classified as highly palatable, 39% as moderately palatable, and 32% as unpalatable. Across all the soil types, Digitaria eriantha had the highest (p < 0.05) crude protein (CP) (106.5 g/kg DM) content when compared to other grass species. In the Avalon soil type, D. eriantha had the lowest (p < 0.05) neutral detergent fiber (NDF) (696.4 g/kg DM). Across all soils, D. eriantha, Aristida congesta, Eragrostis curvula, Eragrostis gummiflua, and Eragrostis plana grasses had the same (p > 0.05) 48-h in vitro ruminal dry matter degradability Hutton soil had a higher proportion of common and dominant grass species as well as more palatable species with higher crude protein content than Avalon and Clovelly soils. However, for all three rangelands, there is a need for supplementary feeding to enhance the production efficiency of livestock given that the nutritive value of grasses was low.

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9

Wieck, Angelika. "Prevention of bipolar episodes with lithium in the perinatal period." British Journal of Psychiatry 211, no. 1 (July 2017): 3–4. http://dx.doi.org/10.1192/bjp.bp.116.193508.

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SummaryBecause lithium is now recommended as the initial long-term treatment for bipolar disorder in general and has a lower teratogenic potential than originally reported, it may become more frequently prescribed in childbearing women. The article by Wesseloo et al in this issue provides helpful data and guidance for managing lithium dosing in the perinatal period.

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10

Klein, Richard G. ": The Omo Micromammals: Systematics and Paleoecology of Early Man Sites from Ethiopia . Henry B. Wesselman." American Anthropologist 88, no. 1 (March 1986): 231–32. http://dx.doi.org/10.1525/aa.1986.88.1.02a00710.

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11

Lucas, Spencer G. "The Omo Micromammals: Systematics and Paleoecology of Early Man Sites from Ethiopia. Henry B. Wesselman." Journal of Anthropological Research 41, no. 1 (April 1985): 115–16. http://dx.doi.org/10.1086/jar.41.1.3630276.

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12

Sundsbø, Astrid Ouahyb. "Universal Parenting Support in Norway – An Unfulfilled Promise." Social Policy and Society 17, no. 3 (February 7, 2018): 503–17. http://dx.doi.org/10.1017/s1474746417000586.

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This article examines the expansion and underlying aims of structured parenting support in Norway. Norway's approach to parenting support differs from that of most other countries (Glavin and Schaffer, 2014), in supposedly being universal and offered to all parents (Eng et al., 2017). However, it is difficult to determine whether parenting support in Norway is actually unique, since little is known about how it is implemented in practice (Bråten and Sønsterudbråten, 2016; Wesseltoft-Rao et al., 2017). This article contributes further knowledge of how parenting support travels from national-level policy-making down to the level of municipal institutions where it is implemented. The analysis draws upon insights from a comprehensive case study in Bergen, Norway's second largest city, that included fieldwork observations and service mapping over a period of two years (2015–2017), a large number of in-depth interviews with various stakeholders, and analysis of relevant documents (advertisements, project applications and project reports, budgets, etc.).

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13

Jacobs, Louis L. "Review of Henry B. Wesselman, The Omo Micromammals: Systematics and Paleoecology of Early Man Sites from Ethiopia." Journal of Vertebrate Paleontology 5, no. 3 (September 1985): 281–83. http://dx.doi.org/10.1080/02724634.1985.10011864.

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14

Flynn, Lawrence J. "The Omo micromammals. By H. B. Wesselman. Basel: Karger. 1985. × + 222 pp., figures, tables, references. $58.75 (cloth)." American Journal of Physical Anthropology 69, no. 4 (April 1986): 554–55. http://dx.doi.org/10.1002/ajpa.1330690419.

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15

Parmenter, Jon. "In Search of Peace and Prosperity: New German Settlements in Eighteenth-Century Europe and America, edited by Hartmut Lehmann, Herrmann Wellenreuther, and Renate Wilson in cooperation with John B. Frantz and Carola WesselIn Search of Peace and Prosperity: New German Settlements in Eighteenth-Century Europe and America, edited by Hartmut Lehmann, Herrmann Wellenreuther, and Renate Wilson in cooperation with John B. Frantz and Carola Wessel. University Park, Pennsylvania, Pennsylvania State University Press, 1999. xii, 332 pp. $60.00 U.S. (cloth), $21.50 U.S. (paper)." Canadian Journal of History 37, no. 3 (December 2002): 614–16. http://dx.doi.org/10.3138/cjh.37.3.614.

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16

Howarth, Geoffrey H., Andrea Giuliani, Ashton Soltys, and Yannick Bussweiler. "Compositional variations in primitive kimberlite melts and entrained mantle cargo from a global survey of trace element compositions in kimberlite olivine." Journal of Petrology, July 5, 2022. http://dx.doi.org/10.1093/petrology/egac062.

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Abstract Olivines are the dominant phase of kimberlites and the majority of grains display distinct compositional zoning with xenocrystic cores surrounded by magmatic rims. Previous work has documented large variations in both core and rim major and minor element compositions in kimberlites globally, which has been related to variable entrainment and assimilation of sub-continental lithospheric mantle (SCLM) material. However, there is limited knowledge of trace element variations in olivine from kimberlites and it is unclear whether mantle assimilation has any effect on the trace element composition of kimberlite melts. To fill this gap, we present a global survey of olivine trace element compositions, along with previously reported major and minor element compositions, for samples representing the full spectrum of olivine compositional variations in kimberlites, including samples from Lac de Gras, Canada (Grizzly, Koala), Kimberley, South Africa (Bultfontein, De Beers, Kimberley Big Hole, Wesselton), Kaalvallei, South Africa (New Robinson, Samada), and Alto Paranaiba, Brazil (Limpeza-18, Tres Ranchos-04). Trace element concentrations of olivine cores can discriminate between those derived from the disaggregation of peridotitic material and those related to the megacryst suite. The megacrystic olivine cores exhibit a negative correlation between Al and Mn, which is absent in peridotite-derived cores, and are characterised by high concentrations of temperature dependent elements (e.g., Al, Na, V) as well as Zn, Ti, and Mn. Following pre-screening of cores for megacrystic and spinel peridotite derived grains, we applied the Al-in-olivine thermometer to assess the P-T equilibration conditions of cores in equilibrium with garnet and estimate the sampling depth of kimberlite magmas in the lithospheric mantle. Our results are consistent with predominant entrainment of deep lithosphere xenocrysts in highly diamondiferous compared to diamond-poor kimberlites. Temperature dependent elements display a gradational increase with depth due to higher T with Ca, Cu and to a lesser extent Zn and Ti being higher and Mg# lower toward the base of the SCLM, which is consistent with melt modification of the lower lithosphere. The Zn, Ti, Co, Mn, Li, Al, Cr, Na, and V concentrations of magmatic olivine rims display systematic variations that have a negative correlation with Mg# (whereas Cr is positively correlated). Lac de Gras olivine feature Mg-rich rims (Mg# >90) and low concentrations of these trace elements whereas the Fe-rich olivine rims (Mg# ~85) of the Kaalvallei kimberlites have higher concentrations of these elements, with the Kimberley and Alto Paranaiba kimberlites being intermediate. Direct correlations between average Ti, Zn, Co and Li compositions of olivine cores and rims suggests that the olivine rim (i.e., proxy for primitive melt) variations are related to variable assimilation of metasomatised SCLM and can be effectively used to track the composition of the lithospheric column that is traversed by kimberlite magmas. These observations further imply an intimate link between early proto-kimberlite melt, leading to formation of megacrystic olivine at the base of the SCLM, and the composition of kimberlite melts which entrain and assimilate these products. We conclude that lithospheric mantle assimilation has a major and previously overlooked influence on the trace element composition of kimberlite magmas.

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17

Soltys, Ashton, Andrea Giuliani, David Phillips, and Vadim S. Kamenetsky. "Kimberlite Metasomatism of the Lithosphere and the Evolution of Olivine in Carbonate-rich Melts — Evidence from the Kimberley Kimberlites (South Africa)." Journal of Petrology 61, no. 6 (June 2020). http://dx.doi.org/10.1093/petrology/egaa062.

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Abstract Olivine is the most abundant phase in kimberlites and is stable throughout most of the crystallization sequence, thus providing an extensive record of kimberlite petrogenesis. To better constrain the composition, evolution, and source of kimberlites we present a detailed petrographic and geochemical study of olivine from multiple dyke, sill, and root zone kimberlites in the Kimberley cluster (South Africa). Olivine grains in these kimberlites are zoned, with a central core, a rim overgrowth, and occasionally an external rind. Additional ‘internal’ and ‘transitional’ zones may occur between the core and rim, and some samples of root zone kimberlites contain a late generation of high-Mg olivine in cross-cutting veins. Olivine records widespread pre-ascent (proto-)kimberlite metasomatism in the mantle including the following features: (1) relatively Fe-rich (Mg# <89) olivine cores interpreted to derive from the disaggregation of kimberlite-related megacrysts (20 % of cores); (2) Mg–Ca-rich olivine cores (Mg# >89; >0·05 wt% CaO) suggested to be sourced from neoblasts in sheared peridotites (25 % of cores); (3) transitional zones between cores and rims probably formed by partial re-equilibration of xenocrysts (now cores) with a previous pulse of kimberlite melt (i.e. compositionally heterogeneous xenocrysts); (4) olivine from the Wesselton water tunnel sills, internal zones (I), and low-Mg# rims, which crystallized from a kimberlite melt that underwent olivine fractionation and stalled within the shallow lithospheric mantle. Magmatic crystallization begins with internal olivine zones (II), which are common but not ubiquitous in the Kimberley olivine. These zones are euhedral, contain rare inclusions of chromite, and have a higher Mg# (90·0 ± 0·5), NiO, and Cr2O3 contents, but are depleted in CaO compared with the rims. Internal olivine zones (II) are interpreted to crystallize from a primitive kimberlite melt during its ascent and transport of olivine toward the surface. Their compositions suggest assimilation of peridotitic material (particularly orthopyroxene) and potentially sulfides prior to or during crystallization. Comparison of internal zones (II) with liquidus olivine from other mantle-derived carbonate-bearing magmas (i.e. orangeites, ultramafic lamprophyres, melilitites) shows that low (100×) Mn/Fe (∼1·2), very low Ca/Fe (∼0·6), and moderate Ni/Mg ratios (∼1·1) appear to be the hallmarks of olivine in melts derived from carbonate-bearing garnet-peridotite sources. Olivine rims display features indicative of magmatic crystallization, which are typical of olivine rims in kimberlites worldwide; that is, primary inclusions of chromite, Mg-ilmenite and rutile, homogeneous Mg# (88·8 ± 0·3), decreasing Ni and Cr, and increasing Ca and Mn. Rinds and high-Mg olivine are characterized by extreme Mg–Ca–Mn enrichment and Ni depletion, and textural relationships indicate that these zones represent replacement of pre-existing olivine, with some new crystallization of rinds. These zones probably precipitated from evolved, oxidized, and relatively low-temperature kimberlite fluids after crustal emplacement. In summary, this study demonstrates the utility of combined petrography and olivine geochemistry to trace the evolution of kimberlite magmatic systems from early metasomatism of the lithospheric mantle by (proto-)kimberlite melts, to crystallization at different depths en route to surface, and finally late-stage deuteric or hydrothermal fluid alteration after crustal emplacement.

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