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单个锆石晶体的U-Pb同位素测量和结合形态分析,可以鉴别西Gotthard(瑞士,中阿尔卑斯)的瓦里斯坎(Variscan)岩墙Saedelhorn闪长岩锆石总体内三个组分截然不同的锆石:(ⅰ) 锆石总体中94％的颗粒是由过冷消失标志急速生长具有显著的骨骸形态的长形晶体。(ⅱ) 总体的5％是由混浊的、大部分半自形的锆石组成,经常地出现D-型形态(按Pupin和Turco的分类法)和骨骸变种对比提高了铀含量。(ⅰ)组与(ⅱ)组锆石中单晶和多粒的U-Pb同位素数据确定了岩墙293+5/-4Ma的一个侵入年龄。(ⅲ)少数,透明锆石晶体(锆石总体的<1％)给出U-Pb表面年龄在370-490Ma范围,所呈形态及同位素特征十分类似被这岩墙侵入的加里东的直向演化。这点含有吸收了在肉眼可见的、同类的岩墙样品的全岩组分存在的意思。用多粒锆石组分和常规分析所得的资料,和用逐粒分析资料的对比证实,用单晶U-Pb测年使年龄精度大大提高。而且,沿着它的途径上升到目前所处部位的岩浆所同化的锆石组分进行定量鉴定,用后种技术是可行的。这样的锆石颗粒可能是各种类型岩浆都有的。关于地壳岩层的年龄和成分的有用资料直接观察是不易的,而应用精确的显微分析技术成为可能。 Saedelhorn岩墙侵入的时间在~(143)Nb/~(144)Nd((?)_(Nd)=-2.7)的下初始点,需要由地壳源派下出岩浆的部分或整体。对地壳母体来说,获得1050Ma模式年龄(T_(DM))表明,元古代地壳是包括Gotthard地区Variscan侵入体的岩石成因。
U-Pb isotopic measurements and morphological analyzes of individual zircon crystals allow the identification of three distinct zirconiums from the zircons of the Saedelhorn diorite in the Variscan dikes of the West Gotthard (Switzerland, the Central Alps) Stone: (i) 94% of the total grains of zircon are rapidly grown as elongated crystals with significant bone morphologies by signs of sub-cooling disappearance. (Ii) 5% of the total is composed of turbid, mostly semi-authigenic zircons, and uranium content is increased by the frequent occurrence of D-forms (by the Pupin and Turco classification) and skeletal variants. U-Pb isotopic data of single and multiple grains from (i) and (ii) groups of zircons established an intrusion age of 293 + 5 / -4Ma in the dike. (Iii) A few, transparent zircon crystals (<1% of the total zircon) give a U-Pb surface age range of 370-490 Ma, with morphological and isotopic characteristics quite similar to those of the Caledonian intrusive evolution. This contains the meaning of the presence of the whole rock component that absorbs the same type of rock wall sample visible to the naked eye. Using multi-grain zircon compositions and data obtained from routine analyzes, and comparisons of grain-by-grain analyzes, the age accuracy was significantly improved using single-crystal U-Pb dating. Furthermore, the quantitative identification of zircon components that have been assimilated by the magma up to its current location along its path is feasible with the latter technique. Such zircon particles may be of all types of magma. It is not easy to visualize useful information about the age and composition of crustal rocks, and the use of precise microscopic analysis techniques is possible. The intrusion time of the Saedelhorn dyke is under the initial point of ~ (143) Nb / ~ (144) Nd (Nd) -2.7), and some or all of the magma needs to be derived from the crust. For the crustal mantle, the 1050Ma model age (T_ (DM)) shows that Proterozoic crust is a rock formation that includes the Variscan intrusion in Gotthard.