Petrogenesis of the Early Proterozoic Matachewan dyke swarm, Canada, and implications for magma emplacement and subsequent deformation
Petrogenesis of the Early Proterozoic Matachewan dyke swarm, Canada, and implications for magma emplacement and subsequent deformation
复制标题
加拿大早元古代马塔切万岩脉群的岩石成因及其对岩浆侵位和随后变形的影响
DOI：
10.1139/e01-044
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发表时间：
2001
影响因子：
1.4
通讯作者：
H. Halls
中科院分区：
文献类型：
--
作者：
W. C. Phinney;H. Halls
对来自马塔切万巨型辐射群的249个岩脉的细粒边缘物质进行的主、次、稀土元素分析表明，任何简单的分馏模型都不能产生成分范围。相反，一个两阶段的过程是必需的，即熔体被修改的分馏和同化的下地壳物质，在上升和积水在较浅的地壳水平（1520公里的最大值），在那里的组合的分离结晶，斜长石斑晶形成，并定期熔体补充发生。这些浅的地壳腔室充当了众多堤坝的供给者。与这些观测结果相一致的一个假设涉及一个广泛的上升羽流，它将在一个大面积上提供异质熔体，并伴随着应力，可能产生一个放射状的堤坝。在寻找侧向岩浆流的迹象时，沿沿着四个横穿西部子群的样品进行的成分纵向变化的比较表明，没有横向岩浆流的迹象。
Major, minor, and rare-earth element analyses of fine-grained marginal material from 249 dykes of the Matachewan giant radiating swarm show that the range in compositions cannot be produced by any simple fractionation model. Instead a two-stage process is required, whereby melts were modified by both fractionation and assimilation of lower crustal material, before rising and ponding at shallower crustal levels (1520 km maximum), where a combination of fractional crystallization, plagioclase phenocryst formation, and periodic melt replenishment took place. These shallow crustal chambers acted as feeders for the numerous dykes. One hypothesis compatible with these observations involves an extensive rising plume that would provide heterogeneous melts over a large area accompanied by stresses that could produce a radial pattern of dykes. In a search for indications of lateral magma flow, a comparison of longitudinal variations in composition along four sample traverses across the western subswarm showed no t...