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Showing 1 to 8 of 8 for “"Nephelinite"”.
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Geochemistry and petrogenesis of the Tsirub nephelinite-basanite intrusions, Aus, southern Namibia
Nephelinite-basanite intrusions found on the Tsurib farm near Aus in southern Namibia are described for the first time. The petrography is very similar to each other wih texture ranging from porphyritic to microporphyritic where olivine is dominant, and sometimes the only, …
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Petrogenesis of natrocarbonatite at Ol Doinyo Lengai, East Africa—evidence from Fe and U isotope variations
… erupted coexisting natrocarbonatites and nephelinites. Numerous studies have been aimed at understanding how ODL natrocarbonatite forms. Liquid immiscibility is a favored hypothesis although condensate fluid separation is an alternative model. However, the exact mechanism that forms the …
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Alkaline igneous rocks of the coastal belt, south of Luderitz, South West Africa : a petrological study
… (Eocene) as well as the smaller melilitite and nephelinite intrusions. Granitberg is a circular foyaite complex, in the centre of which is preserved a large fragment of sedimentary rocks that originally formed the roof of the intrusion. The foyaites have been emplaced into the feldspathic …
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The Sukulu complex, Eastern Uganda and The origin of the African carbonatites
… extent plagioclase from a parent basaltic magma. Nephelinite is the type most commonly produced and constitutes the main lava flows of these volcanoes. The development of rocks containing melilite, melanite and primary calcite from nephelinitic magma is shown to be the result of the relative …
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The petrogenesis and geochemistry of the Namaqualand olivine melilitite pipe cluster, western South Africa
… and diatremes containing olivine melilitite and nephelinite, spanning an age range of 35-56 Ma. A related carbonatite complex containing olivine melilitite is also found within this cluster, with an emplacement age of ≈ 55 Ma. The Namaqualand cluster represents the southernmost component of the …
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The geochemistry and petrogenesis of lavas from the Comores Archipelago, Western Indian Ocean (Volume 2)
… are classified as alkali basalts, basanites and nephelinites. The lavas of Mayotte, the oldest Comorean island, were erupted during three phases of volcanic activity and display greater chemical variation than both Grande Comore and Moheli lavas. Mayotte lavas range in composition from alkali …
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The geochemistry and petrogenesis of lavas from the Comores Archipelago, Western Indian Ocean (Volume 1)
… are classified as alkali basalts, basanites and nephelinites. The lavas of Mayotte, the oldest Comorean island, were erupted during three phases of volcanic activity and display greater chemical variation than both Grande Comore and Moheli lavas. Mayotte lavas range in composition from alkali …
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Magmatic volatiles at rifts and arcs: Sources and fractionation effects
… Sciences in January, 2013) we show that nephelinite melts at Oldoinyo Lengai are the most carbon-rich natural silicate melts known to science. However, we argue that the mantle source for these melts is not unusually rich in carbon. Rather, extreme degrees of fractional crystallization …