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The Sheahan Diamond Literature Reference Compilation - Technical, Media and Corporate Articles based on Major Region - Algeria
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 Region 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 addition most references have been tagged with one or more region words. In an effort to make it easier for users to track down articles related to a specific region, KRO has extracted these region words and developed a list of major region words presented in the Major Region Index to which individual region words used in the article reference have been assigned. Each individual Region Report contains in chronological order all the references with a region word associated with the Major Region word. Depending on the total for each reference type - technical, media and corporate - the references will be either in their own technical, media or corporate Region Report, or combined in a single report. Where there is a significant number of technical references there will be a technical report dedicated to the technical articles while the media and corporate references are combined in a separate region report. References that were added in the most recent monthly update are highlighted in yellow within the Region Report. The Major Region words have been defined by a scale system of "general", "continent", "country", "state or province" and "regional". Major Region words at the smaller scales have been created only when there are enough references to make isolating them worthwhile. References not tagged with a Region are excluded, and articles with a region word not matched with a Major Region show up in the "Unknown" report.
Kimberlite - diamondiferous
Lamproite - diamondiferous
Lamprophyre - diamondiferous
Other - diamondiferous
Kimberlite - non diamondiferous
Lamproite - non diamondiferous
Lamprophyre - non diamondiferous
Other - non diamondiferous
Kimberlite - unknown
Lamproite - unknown
Lamprophyre - unknown
Other - unknown
Future Mine
Current Mine
Former Mine
Click on icon for details about each occurrence. Works best with Google Chrome.
CITATION: Faure, S, 2010, World Kimberlites CONSOREM Database (Version 3), Consortium de Recherche en Exploration Minérale CONSOREM, Université du Québec à Montréal, Numerical Database on consorem.ca. NOTE: This publicly available database results of a compilation of other public databases, scientific and governmental publications and maps, and various data from exploration companies reports or Web sites, If you notice errors, have additional kimberlite localizations that should be included in this database, or have any comments and suggestions, please contact the author specifying the ID of the kimberlite: [email protected]
Kahoui, M., Kemainsky, F.V., Griffin, W.L., Belousova, E., Mahdjoub, Y., Chabane, M.
Detrital pyrope garnets from the El Kseibat area, Algeria: a glimpse into the lithospheric mantle beneath the north-eastern edge of the West African Craton.
Journal of African Earth Sciences, In press available, 46p.
Kaminsky, F.V., Kahoui, M.,Mahdjoub, Y., Belousova, E., Griffin, W.L.,O'Reilly, S.Y.
Pyrope garnets from the Eglab Shield, Algeria: look inside the Earth's mantle in the West African Craton and suggestions about primary sources of diamond and indicator minerals.
Vladykin, N.V. ed. Deep seated magmatism, its sources and plumes, Russian Academy of Sciences, pp. 73-103.
Journal of Volcanology and Geothermal Research, in press available 15p.
Africa, Algeria
Lamproite
Abstract: The late Miocene (11-9 Ma) volcanic rocks of Kef Hahouner, ~ 40 km NE of Constantine (NE Algeria), are commonly classified as lamproites in literature. However, these rocks are characterized by an anhydrous paragenesis with plagioclase and Mg-rich olivine phenocrysts, set in a groundmass made up of feldspars, pyroxenes and opaque minerals. Thus, we classify the Kef Hahouner rocks as ultrapotassic shoshonites and latites, having K2O > 3 wt.%, K2O/Na2O > 2.5, MgO > 3-4 wt.%, SiO2 < 55-57 wt.% and SiO2/K2O < 15. All the investigated samples show primitive mantle-normalized multi-element patterns typical of orogenic (arc-type) magmas, i.e. enriched in LILE (e.g. Cs, Rb and Ba) and LREE (e.g. La/Yb = 37-59) with respect to the HFSE, peaks at Pb and troughs at Nb and Ta. Initial isotopic ratios are in the range of 87Sr/86Sr = 0.70874-0.70961, 143Nd/144Nd = 0.51222-0.51223, 206Pb/204Pb = 18.54-18.60, 207Pb/204Pb = 15.62-15.70 and 208Pb/204Pb = 38.88-39.16. The Kef Hahouner volcanic rocks show multi-element patterns similar to the other circum-Mediterranean lamproites and extreme Sr, Nd and Pb isotopic compositions. Nevertheless, the abundant plagioclase, the presence of Al-rich augite coupled with high Al2O3 whole rock compositions (9.6-21.4 wt.%), and the absence of phlogopite are all at inconsistent with the definition of lamproite. We reviewed the rocks classified as lamproites worldwide, and found that many of these rocks, as for the Kef Hahouner samples, should be actually defined as "normal" potassic to ultrapotassic volcanic rocks. Even the grouping of lamproites into "orogenic" and "anorogenic" types appears questionable.
Earth and Planetary Science Letters, Vol. 474, pp. 215-225.
Africa, Algeria
diamond inclusions
Abstract: Diamond-bearing UHP metamorphic rocks witness for subduction of lithospheric slabs into the mantle and their return to shallow levels. In this study we present U-Pb and trace elements analyses of zircon and rutile inclusions from a diamond-bearing garnet megacryst collected in a mélange unit exposed on the northern margin of Africa (Edough Massif, NE Algeria). Large rutile crystals (up to 300 ?m in size) analyzed in situ provide a U-Pb age of 32.4 ± 3.3 Ma interpreted as dating the prograde to peak subduction stage of the mafic protolith. Trace element analyses of minute zircons (?30 ?m) indicate that they formed in equilibrium with the garnet megacryst at a temperature of 740-810 °C, most likely during HP retrograde metamorphism. U-Pb analyses provide a significantly younger age of 20.7 ± 2.3 Ma attributed to exhumation of the UHP units. This study allows bracketing the age of UHP metamorphism in the Western Mediterranean Orogen to the Oligocene/early Miocene, thus unambiguously relating UHP metamorphism to the Alpine history. Exhumation of these UHP units is coeval with the counterclockwise rotation of the Corsica-Sardinia block and most likely resulted from subduction rollback that was driven by slab pull.
Abstract: Ihouhaouene area in In Ouzzal terrane (Hoggar, South Algeria) is exceptional by numerous carbonatite complexes systematically associated to syenites. They constitute one of the oldest carbonatite emplaced at 2 Ga. Various types of carbonatites are distinguished by their successive placement and pegmatitic to brecciated appearance. The first-generation of carbonatites are always brecciated with elements of syenite and carbonate cement with calcite, apatite, alkali feldspar, wollastonite, clinopyroxene +/- sphene, allanite, quartz and garnet. Late carbonatite intrusions appear in small pegmatitic veins rich in apatite (3-50 mm). All carbonatites are calciocarbonatites (38-50 wt% CaO) with silica content ranging from 5 to 21 wt% SiO2. The high silica content is interpreted as assimilation of syenite material during emplacement. Carbonatites have high Rare Earth Element (REE) concentrations with high Ligh REE/Heavy REE fractionation (e.g. 1088 ppm La, La/Yb= 144-198) and variable concentrations in Th (26.5-197 ppm). The REE concentrations are mainly controlled by apatite phenocrysts (30-40 vol.%) with 4-9 wt% REE. In late pegmatitic carbonatite, REE-rich apatites are green-yellow phenocrysts with britholite exsolution (up to 40 vol.%, Ca4(REE)6 (SiO4,PO4)6 (OH,F,Cl)2). Britholites are hexagonal and occur as fine lamellar exsolutions (<10 um) in the same crystallographic axis (001) than apatites or as irregularshaped grains (10-200 um). All britholites contain 8-16 wt% La, 21-43 wt% Ce and 7-12 wt% Nd. The apatite-britholite exsolutions correspond to a substitution of the trivalent rareearth elements (REE3+) and Si4+ for Ca2+ and P5+. The REE substitution is accompanied by a change in volatile composition with F-rich apatite and Cl-rich britholite indicating that Si and Cl-rich hydrothermal fluids are present at the late stage of carbonatite evolution leading to REEenrichment and the crystallization of REE minerals.
Abstract: Kimberlite is the host rock of diamonds and varies widely in geological and mineralogical features as well as color, processing capability, and dewatering characteristics. This study investigated the dewatering behavior of problematic Angolan kimberlites. The presence of clay minerals in kimberlite causes difficulties in dewatering due to high flocculant demand, poor supernatant clarity, and low settling rates. Identifying critical parameters governing the settling behavior will assist in managing the settling behavior of different kimberlite slurries. The influence of particle size, pH of the kimberlite slurry, cation exchange capacity, exchangeable sodium percentage, and smectite content of the kimberlite on the settling rate were investigated for 18 different African kimberlite samples. The settling rate and slurry bed compaction during natural settling were also measured for the kimberlite slurries. Seventeen different Angolan clay-rich kimberlites and one South African clay-rich kimberlite were tested, and, except for two kimberlites, colloidal stability was experienced during natural settling. The pH values of the kimberlite slurries ranged between 9 and 11, which is similar to the pH band where colloidal stability was found during earlier research. The results indicate that colloidal stable slurries were experienced with kimberlites that had exchangeable sodium percentages as low as 0.7%. The cation exchange capacity of the various kimberlites differentiated more distinctly between colloidal stability and instability. A new model is proposed whereby clay-rich kimberlites with a cation exchange capacity of more than 10cmol/kg will experience colloidal stability if the pH of the solvent solution is within the prescribed pH range of 9-11.The Trans-Saharan Belt is one of the most important orogenic systems constitutive of the Pan-African cycle, which, at the end of the Neoproterozoic, led to the formation of the Gondwana Supercontinent. It is marked by the opening and closing of oceanic domains, collision of continental blocks and the deformation of thick synorogenic sedimentary basins. It extends from north to south over a distance of 3000?km in Africa, including the Nigerian Shield and the Tuareg Shield as well as their counterparts beneath the Phanerozoic oil-rich North- and South-Saharan sedimentary basins. In this study, we take advantage of potential field methods (magnetism and gravity) to analyze the crustal-scale structures of the Tuareg Shield terranes and to track these Pan-African structures below the sedimentary basins, offering a new, >1000?km extent. The map interpretations are based on the classical potential field transforms and two-dimensional forward modeling. We have identified geophysical units and first-order bounding lineaments essentially defined owing to magnetic and gravimetric anomaly signatures. In particular, we are able to highlight curved terminations, which in the Trans-Saharan context have been still poorly documented. We provide for the first time a rheological map showing a categorization of contrasted basement units from the south of the Tuareg Shield up to the Atlas Belt. These units highlight the contrasted rheological behavior of the Tuareg tectonostratigraphic terranes during (i) the northerly Pan-African tectonic escape characteristic of the Trans-Saharan Belt and (ii) the North Sahara basin development, especially during intraplate reworking tied to the Variscan event. The discovery of a relatively rigid E-W oriented unit to the south of the Atlas system, and on which the escaping Pan-African terranes were blocked, offers a new perspective on the structural framework of the north-Gondwana margin. It will help to understand how occurred the rendezvous of the N-S oriented Pan-African terranes and the E-W oriented Cadomian peri-Gondwanan terranes.
Abstract: Subduction-Transform Edge Propagator (STEP) faults are the locus of continual lithospheric tearing at slab edges, resulting in sharp changes in the lithospheric and crustal thickness and triggering lateral and/or near-vertical mantle flow. However, the mechanisms at the lithospheric mantle scale are still poorly understood. Here, we present the microstructural study of olivine-rich lherzolite, harzburgite and wehrlite mantle xenoliths from the Oran volcanic field (Tell Atlas, NW Algeria). This alkali volcanic field occurs along a major STEP fault responsible for the Miocene westward slab retreat in the westernmost Mediterranean. Mantle xenoliths provide a unique opportunity to investigate the microstructures in the mantle section of a STEP fault system. The microstructures of mantle xenoliths show a variable grain size ranging from coarse granular to fine-grained equigranular textures uncorrelated with modal variations. The major element composition of the mantle peridotites provides temperature estimates in a wide range (790-1165?°C) but in general, the coarse-grained and fine-grained peridotites suggest deeper and shallower provenance depth, respectively. Olivine grain size in the fine-grained peridotites depends on the size and volume fraction of the pyroxene grains, which is consistent with pinning of olivine grain growth by pyroxenes as second phase particles. In the coarse-grained peridotites, well-developed olivine crystal preferred orientation (CPO) is characterized by orthorhombic and [100]-fiber symmetries, and orthopyroxene has a coherent CPO with that of olivine, suggesting their coeval deformation by dislocation creep at high-temperature. In the fine-grained microstructures, along with the weakening of the fabric strength, olivine CPO symmetry exhibits a shift towards [010]-fiber and the [010]- and [001]-axes of orthopyroxene are generally distributed subparallel to those of olivine. These data are consistent with deformation of olivine in the presence of low amounts of melts and the precipitation of orthopyroxenes from a melt phase. The bulk CPO of clinopyroxene mimics that of orthopyroxene via a topotaxial relationship of the two pyroxenes. This observation points to a melt-related origin of most clinopyroxenes in the Oran mantle xenoliths. The textural and geochemical record of the peridotites are consistent with interaction of a refractory harzburgite protolith with a high-Mg# melt at depth (resulting in the formation of coarse-grained clinopyroxene-rich lherzolite and wehrlite), and with a low-Mg# evolved melt in the shallow subcontinental lithospheric mantle (forming fine-grained harzburgite). We propose that pervasive melt-peridotite reaction - promoted by lateral and/or near-vertical mantle flow associated with lithospheric tearing - resulted in the synkinematic crystallization of secondary lherzolite and wehrlite and played a key effect on grain size reduction during the operation of the Rif-Tell STEP fault. Melt-rock reaction and secondary formation of lherzolite and wehrlite may be widespread in other STEP fault systems worldwide.
Abstract: Carbonatites and syenites from Ihouhaouene (2 Ga; In Ouzzal terrane, Hoggar, South of Algeria) have close spatial relationships. Their analogous mineral assemblages with diopside/hedenbergite (cpx), apatite, wollastonite +/- calcite and alkali-feldspar suggest that they were emplaced from a common igneous parental event. Carbonatites from In Ouzzal terrane are calciocarbonatites and form a continuous range of whole-rock major and trace element composition from Sipoor carbonatite (<20 wt.% SiO2; 24-36 wt.% CO2) to Si-rich carbonatite (20-35 wt.% SiO2; 11-24 wt.% CO2) then white syenite (52-58 wt.% SiO2; 0.1-6.5 wt.% CO2) and red syenite (57-65 wt.% SiO2; 0.1-0.4 wt.% CO2). Equilibrium calculations reveal that apatite (Ce/Lu= 1690-6182; Nb/Ta >50) and cpx (Ce/Lu= 49-234; Nb/Ta<10) from Si-rich carbonatites and white syenites crystallized from a REEenriched carbonate melt and an evolved silicate melt, respectively. Likewise, Si-poor carbonatites have a higher REE contents in calculated apatite equilibrium melts than in their cpx and a wide range of Nb/Ta ratios with a majority of subchondritic value (<10) that reflects the segregation of the carbonate fraction from an evolved parental melt. Otherwise, red syenites have similar REE contents in apatite and clinopyroxene equilibrium melts (Nb/Ta>10) suggesting an origin from homogeneous evolved melt batches. Both mineralogical and geochemical features reveal the intimate link between carbonatites and syenites and their cogenetic signature. Immiscibility and fractional crystallization processes modelling explain the trace element contents and low Nb/Ta ratio in minerals. These processes were partly counterbalanced by intermingling of partially crystallized melt fractions and hybridization of segregated minerals during the progressive cooling of a silico-carbonated mantle melt.
Abstract: A review of the compositional features of Tunisia, Algeria, and Morocco phosphorites is proposed in order to assess and compare the paleoenvironmental conditions that promoted the deposit formation as well as provide information about their economic perspective in light of growing worldwide demand. Since these deposits share a very similar chemical and mineralogical composition, the attention was focused on the geochemistry of rare earth elements (REEs) and mostly on ?REEs, Ce and Eu anomalies, and (La/Yb) and (La/Gd) normalized ratios. The REEs distributions reveal several differences between deposits from different locations, suggesting mostly that the Tunisian and Algerian phosphorites probably were part of the same depositional system. There, sub-reducing to sub-oxic conditions and a major REEs adsorption by early diagenesis were recorded. Conversely, in the Moroccan basins, sub-oxic to oxic environments and a minor diagenetic alteration occurred, which was likely due to a different seawater supply. Moreover, the drastic environmental changes associated to the Paleocene-Eocene Thermal Maximum event probably influenced the composition of Northern African phosphorites that accumulated the highest REEs amounts during that span of time. Based on the REEs concentrations, and considering the outlook coefficient of REE composition (Koutl) and the percentage of critical elements in ?REEs (REEdef), the studied deposits can be considered as promising to highly promising REE ores and could represent a profitable alternative source for critical REEs.
