Structural Controls on Magma Transport and Vertical Coupling in the Continental Lithosphere

2003年4月26日至5月6日，在新西兰峡湾举行了一个国际实地论坛，为固体地球科学界的成员提供了一个机会，来研究岩浆产生、分离和通过大陆地壳运输的机制，以及这些过程如何影响岩石圈的机械演化。峡湾地区的位置意义重大，因为很少有野外地点能让地球科学家直接研究下地壳大片区域内同时演化的构造和岩浆特征。峡湾地区含有罕见的高压混辉岩和下地壳结构特征，这些特征形成于白垩纪山脉系统的异常深层（25-50 km古深度）。这一遗址的壮观保存激发了新的想法，并为评估熔体产生和从下地壳逸出的过程以及迁移的岩浆如何与岩石圈尺度上的变形相互作用提供了基础。讨论的具体问题包括：1)下地壳快速演化的热与结构机制及其对岩石圈演化的影响的证据；2)流体和熔体来源的证据以及岩浆在下地壳中分离和运输的变化机制；3)地壳熔融、麻粒岩相变质与变形的反馈机制；4)地壳熔融和岩浆活动对岩石圈内垂直耦合/解耦过程的影响；5)天然下地壳剪切带的流动模式及其与变形和岩浆搬运过程的关系；6)下地壳变形分配和应变局部化过程的时空控制。峡湾独特的地质环境使30位地球科学家能够交流当前的知识和新思想，这些知识和新思想都是通过特定现场的地质学来很好地表达的。本项目还部分支持5-8名学生和1名博士后参加会议。青年科学家的参与为学生提供了与其他从事相同或相似兴趣领域研究但专业知识不同的地球科学家见面的机会。这也使他们有机会与成熟的科学家互动，并有机会研究一些引人注目的地壳深层过程。

An international field forum in Fiordland, New Zealand (April 26 to May 6, 2003) is providing members of the Solid Earth Science community with an opportunity to examine the mechanisms by which magma is generated, segregated and transported through continental crust and how these processes affect the mechanical evolution of the lithosphere. The Fiordland location is significant because few field sites allow geoscientists to examine directly structural and magmatic features that evolved simultaneously within large sections of the lower crust. Fiordland contains rare exposures of high-pressure migmatite and lower crustal structural features that formed at unusually deep levels of a Cretaceous mountain system (25-50 km paleodepths). The spectacular preservation of features at this site are stimulating new ideas and are providing a basis for evaluating the processes of melt generation and escape from the lower crust and how migrating magma interacts with deformation at the lithospheric scale. Specific issues addressed include: 1) evidence of rapidly evolving thermal and structural regimes in the lower crust and effects on lithosphere evolution; 2) evidence of fluid and melt sources and changing mechanisms of magma segregation and transport through the lower crust; 3) feedback mechanisms among crustal melting, granulite facies metamorphism and deformation; 4) effects of crustal melting and magmatism on vertical coupling/decoupling processes within the lithosphere; 5) flow patterns in natural lower crustal shear zones and their relationship to deformation and magma transport processes; 6) space-time controls on deformation partitioning and strain localization processes in the lower crust. The unique geologic setting of Fiordland allows 30 geoscientists to exchange current knowledge and new ideas that are well expressed by the geology of specific field sites. This project also partially supports 5-8 students and a post-doctoral associate to attend the meeting. The participation of young scientists provides opportunities for students to meet other geoscientists conducting research in the same or similar fields of interest, but with different expertise. It also allows them to interact with mature scientists and an opportunity to study some spectacularly exposed deep crustal processes.