Barium isotope evidence for crystal-melt separation in granitic magma reservoirs
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Muscovite
Fractional crystallization (geology)
Alkali feldspar
Trace element
Based on the data on plagioclase number of granitoids and whole-rock chemical analysis, the author has proposed that the percentage of molecules of albite in the coexisting plagioclase and alkali-feldspar can be obtained by direct conversion through a petro-chemical approach. Then, the result is substituted into the formula of J. A. Whitney and J. C. Stormer, Jr. (1975, 1977) to work out, the temperatures at which the coexisting feldspars crystallized, i.e., the possible rock-forming temperature of granitoids. Rock-forming temperature values computed by this method as described in the present paper are in good agreement with those by other geothermometries.
Alkali feldspar
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Regular and irregular variations were found in the concentration of elements in muscovite and albite in relation to the distance from margin to center of a pegmatite dike near Yellow knife. For example, the magnesium content of muscovite increases towards the center, iron decreases, and lithium varies irregularly.The distribution of sodium and potassium among muscovite, albite, and potassium feldspar is considered in relation to mineral reactions and phase equilibrium. Comparison with experimental data indicates that the pegmatite specimens attained near-equilibrium at approximately 450 °C.
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Pegmatite
Dike
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Alkaline earth metal
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Sn， Nb-Ta 和 W 的稀罕金属矿化作用在 Gebel Dihmit 区域(GDA ) 被遇到，东南的阿斯旺， Egypt.The 矿化作用与白云母花岗石和他们的伟晶岩衍生物有关。伟晶岩根据他们的主要矿物共生被划分成三种类型: K-feldspar-muscovite-tourmaline ， K-feldspar-albite-muscovite 和 albite-K-feldspar-lepidolite veins.Petrogenetic 研究显示那个 Sn 和 Nb-Ta 矿化作用从 late-magmatic 阶段延长到伟晶岩和热水的阶段( GDA ) suite.The albite-K-feldspar-lepidolite 花岗石由钠长石主导地组成， lepidolote ，并且石英与黄玉，K长石和磷矾石。副次要是锆石，独居石， pollucite， columbite 钽铁矿，微晶和 Ta 富有的锡石。石英，黄玉和 K 长石的斑晶沿着生长地区(雪球质地) 包含钠长石板条和偶尔的锂云母晶体的丰富的包括，显示从 subsolvus 的同时的结晶化，残余岩浆。伟晶岩的起源被花岗石的岩浆的分离结晶归因于极端区别。为稀罕金属的经济潜力在 geochemical 辨别图被评估。因此，一些伟晶岩高度是不仅为小规模的 Ta 以碱，而且有希望的目标区分了并且，到更少程度， Sn.The 伟晶岩也在花岗石的连续的代提供 Fe-Mn 和 Nb-Ta 分别的第一个例子给忍受锡石的伟晶岩，它完美地展出在伟晶岩的相应范畴为主要columbite钽铁矿建立的类似的分别趋势。magmatic 起源的铀和 Th 被土矿和 allanite 的存在显示，而热水的矿化作用的证据是象长石和象硅钙铀矿那样的次生矿物的形成那样的岩石为矿物质的改变……
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Pegmatite
Tourmaline
Columbite
Alkali feldspar
Allanite
Prospecting
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Radioluminescence
Alkali feldspar
Anorthite
Thermoluminescence dating
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