Apatite u thhe dating

Posted by / 02-Oct-2019 22:34

Certain rare chemical elements, such as lithium, beryllium, and niobium, that do not readily enter into atomic substitution in the main granite minerals (feldspar, quartz, and mica) become concentrated in the water-rich residual magma.If the crystallization process occurs at a depth of about five kilometres or greater, the water-rich residual magma may migrate and form small bodies of igneous rock, satellitic to the main granitic mass, that are enriched in rare elements.Pegmatites also are the major source of sheet mica and important sources of gemstones, particularly tourmalines and the gem forms of beryl (aquamarine and emerald).dolomite; they sometimes also contain the rare-earth ore minerals bastnaesite, parisite, and monazite, the niobium ore mineral pyrochlore, and (in the case of the carbonatite deposit at Palabora in South Africa) copper sulfide ore minerals. Most carbonatites occur close to intrusions of ultramafic igneous rocks (rocks with silica contents below approximately 50 percent by weight) known as kimberlites and lamproites.These associations suggest a common derivation, but details of the way that carbonatite magmas might concentrate geochemically scarce metals remain conjectural.

These morphometric values are subsequently imported into a Lab View routine to calculate the alpha-ejection correction.Such small igneous bodies, called rare-metal pegmatites, are sometimes exceedingly coarse-grained, with individual grains of mica, feldspar, and beryl up to one metre across.Pegmatites have been discovered on all continents, providing an important fraction of the world’s lithium, beryllium, cesium, niobium, and tantalum.Therefore, the geometry (A) of the mineral grain is very important (Meesters and Dunai, 2002a, b).A correction has to be applied for the loss of radiogenic He generated within an outer rim of the mineral grain by the α-stopping distances (apatite: 25m).

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