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Study of physical-mechanical properties of hard rocks under water-saturated conditions
Published in Vladimir Litvinenko, EUROCK2018: Geomechanics and Geodynamics of Rock Masses, 2018
Nikolai Kuznetcov, Iuliia Fedotova, Alexander Pak
At the first research stage the rock samples were exposed to the uniaxial compression tests and their average compressive strength values were determined (Table 1). The maximum values of compressive strength found corresponding to two types of gneiss, while the minimum ones—to carbonatite and fenite amphibole-feldspar. The character of the rock samples failure was also different. The gneiss samples were failed dynamically, with a wide dispersion of rock particles. The carbonatite and fenite amphibole-feldspar samples were subsided under the load with a slight dispersion of rock particles.
The Fe-REE Ore Deposit hosted by carbonate-alkali ultrabasic complex in Hongcheon, S. Korea.
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
Biotite-hornblende gneiss, wall rock of carbonate injections is altered to syenitic fenite and feldspathic fenite by Na-metasomatism along the injections. The former consists of mainly sugary albite and Na-tirodite and the latter consists of albite and hematite.
A review of the geological settings, ages and economic potentials of carbonatites in the Democratic Republic of Congo
Published in Applied Earth Science, 2021
Georges M. Kasay, Anthony T. Bolarinwa, Olawale K. Aromolaran, Charles Nzolang, Vikandy S. Mambo
The petrography of the Lueshe massifs was described for the first time by De Bethune and Meyer (1956). Meyer and De Bethune (1958) later gave details of the compositions of the carbonatites, syenites and fenites. Other workers focused on the petrography, petrology and geology of the Lueshe Complex (Maravic and Morteani 1980; Maravic et al. 1989; Nasraoui 1996; Kramm et al. 1997). The rock types of Lueshe Complex are presented in Figure 2. They include syenite, carbonatite, fenite, mica schist, quartzite and pyroxenitic rocks. These rocks are covered by thick lateritic soils of between 30 and 150 m. The Busoro and Mutoro Hills are deeply weathered and covered with thick laterites rich in clay and sand minerals. Clay minerals are dominated by kaolinite and montmorillonite. Laterites are also enriched in crandallite, goethite, goyacite, wavellite, florencite, psilomelane and cryptomelane. - Syenites
Petrology and petrogenesis of an intraplate alkaline lamprophyre-phonolite-carbonatite association in the Alpine Dyke Swarm, New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2020
The close spatial association of phonolites and carbonatites, their similar radiogenic and stable isotopic compositions (Barreiro and Cooper 1987; Cooper and Paterson 2008), coupled with the similarity in composition of minerals common to the two rock types (e.g aegirine-rich clinopyroxenes, Cooper 1986, his Figure 4) led to the interpretion that the two magmas most probably originated by immiscibility. In Figure 11, the most alkali-rich phonolites have compositions that plot along the silicate limb of a silicate melt-carbonatite miscibility gap defined by both experimental work (e.g. Brooker and Hamilton 1990; Lee and Wyllie 1997, 1998) and the compositions of natural melt inclusions in minerals from carbonatite complex rocks (e.g. Guzmics et al. 2011). The miscibility gap is dependent on P-T conditions, CO2 and H2O saturation, and parent-rock geochemistry, but with the solvus shown in Figure 11, the conjugate liquid that would coexist with alkali-rich ADS phonolite is an alkali-rich carbonatite. Compositions of ADS carbonatites, like the vast majority of carbonatites elsewhere in the world, cluster along the (SiO2 +Al2O3 +TiO2)–(CaO + MgO + FeO) join and are depleted in alkalis. The development of albite-aegirine ± riebeckite/arfvedsonite fenite from the country rock quartzofeldspathic schist along carbonatite contacts clearly demonstrates how alkalis can be removed from the host carbonatite as a metasomatic fenitising fluid.
Carbonatites: related ore deposits, resources, footprint, and exploration methods
Published in Applied Earth Science, 2018
George J. Simandl, Suzanne Paradis
In some cases, glacial dispersal of ore minerals down-ice from the deposit enhances the size of both the geophysical and geochemical exploration target. For example, the Allan Lake carbonatite in Ontario, Canada, which was discovered by airborne gamma-ray spectrometry (5 km line spacing), is a small unexposed carbonatite body approximately 0.4 km2 in area, not including the fenite zone. The discovery of such a small intrusion was possible because carbonatite-derived material was incorporated into till, increasing concentrations of Ba, Nb, Th, Ce, La, Zn, Mn, and Fe 10 to 20 times, and Y, P, Cu, Pb, Mo, Co, and U 5 to 10 times those of background levels. The initial Th anomaly detected by an airborne gamma-ray survey coincided with the Th-rich till and large Th-bearing boulders that were dispersed down-ice for nearly 5 km from the deposit (Ford et al. 1988).