Isotopic results of the Proterozoic crustal evolution of south-central Sweden; review and conclusions
Isotopic results of the Proterozoic crustal evolution of south-central Sweden; review and conclusions
复制标题
瑞典中南部元古代地壳演化的同位素结果；
作者：
E. Welin
摘要 回顾了瑞典中南部元古代斯维科芬阶基岩的同位素数据。通过各种辐射测量方法对结果的解释确定了同造山和晚造山火成岩事件的年龄分别为1.89-1.85 Ga和1.80-1.78 Ga。早期火山活动可能比 1.87-1.85 Ga 的同造山侵入岩早 15-20 Ma。在 1.85 至 1.80 Ga 的时间跨度内，变形和变质过程引发了深熔熔融，产生了脉状片麻岩和混合岩。在此期间形成的岩石尚未确定年代。晚造山期花岗岩和相关伟晶岩的年龄在 1.80–1.78 Ga 的狭窄区间内。根据 Sm-Nd 数据讨论了 Svecofennian 岩石的起源。沉积岩含有相当大一部分较古老的地壳物质，但在所有火成岩中，源自地幔的成分占主导地位。成因模型表明，晚造山火成岩是由动员的花岗岩物质结晶而成的……
Abstract Isotopic data on the Proterozoic Svecofennian bedrock of south-central Sweden are reviewed. Interpretation of the results by various radiometric methods establishes the ages of the syn-orogenic and late-orogenic igneous events to be 1.89–1.85 Ga and 1.80–1.78 Ga, respectively. Early volcanism is possibly 15–20 Ma older than the syn-orogenic intrusions at 1.87–1.85 Ga. During the time-span from 1.85 to 1.80 Ga deformational and metamorphic processes initiated anatectic melting producing veined gneisses and migmatites. Rocks formed during this time interval have not been dated. The late-orogenic granites and associated pegmatites have ages in a narrow interval of 1.80–1.78 Ga. The origin of the Svecofennian rocks is discussed on the basis of Sm-Nd data. The sedimentary rocks have a considerable portion of older crustal material but in all the igneous rocks a mantle-derived component dominates. Genetic models imply that the late-orogenic igneous rocks crystallized from mobilized granitic material fo...