Collaborative Research: Lithospheric Structure and Evolution of the Rocky Mountains - beginning Phase 2 Geodynamic Processes

美国西部是世界上研究大陆演化的最佳地点之一，因为那里保存着关于大陆的生长、稳定、成熟、裂谷和早期分裂的独特记录。特别是，我们可以看到更古老的岩石圈结构（在这里是太古宙和元古代）是如何影响更年轻的构造事件的，包括主导美国西部的巨大的、目前活跃的造山带高原的发展，以及沿其活跃的西部边缘大陆碎片的逐渐肢解和分散。大陆是200 Ma之前板块相互作用的长期记录者。然而，累积的修改往往掩盖了以前的记录。美国西部的独特之处在于，这部分大陆在元古代围绕一个太古宙“克拉通核”组装，然后在显生宙以高角度截断，从而形成一个与前寒武纪构造斜向的新大陆边缘。其结果是创造了一个广阔的地区——美国西部——在那里大自然“捕捉”到了结构重新激活和大陆改造的所有阶段。CD-ROM（落基山脉大陆动力学）项目的主要目标是了解大陆岩石圈的形成和变化过程。CD-ROM实验的第一阶段是一个为期三年的项目，旨在提高我们对岩石圈的结构和岩石学知识，并验证北美西南部组装期间产生的岩石圈结构在随后的所有岩浆和构造事件（包括与正在进行的软流圈流动有关的事件）中深刻影响大陆岩石圈物理和化学变化的假设。主要研究人员用一系列地震和地质方法研究了两个元古代构造：夏延带和耶梅斯地层。反射、折射和远震调查提供了主要构造的地壳和岩石圈尺度图像。通过对前寒武纪剪切带和显生宙构造的地质研究、包体研究以及对现今地貌的地貌学和挖掘研究，对岩石圈的演化有了更全面的了解。第一阶段汇集了来自14个机构的18名研究人员，其中包括与德国资助的折射团队的合作。有了这些资金，该公司将提供一年的资金，继续处理、解释和整合第一阶段生成的各种数据集，并开始开发地球动力学模型。首席研究人员还将探索数据整合的新方法，以建立岩石圈结构的“主模型”

0003534SmithsonThe western U.S. is one of the best places in the world to study continental evolution because there is a preserved unique record of the growth, stabilization, maturation, rifting, and incipient dismemberment of a continent. In particular, we can see how older lithospheric structures (in this case Archean and Proterozoic) influenced younger tectonic events, including development of the huge, presently active, orogenic plateau that dominates the western U.S. and the progressive dismemberment and dispersal of continental fragments along its active western margin. Continents are the long-term record keepers of plate interactions before 200 Ma. However, accumulated modification often obscures the previous record. The western U.S. is unique in that this part of the continent was assembled in the Proterozoic around an Archean "cratonic core", then was truncated in the Phanerozoic at a high angle so as to create a new continental margin oblique to the Precambrian structures. The result was the creation of a wide region - the western U.S. - where nature "caught" all stages of structural reactivation and continental modification.The main goal of the CD-ROM (Continental Dynamics of the Rocky Mountains) Project is to understand the processes of formation and modification of continental lithosphere. Phase 1 of the CD-ROM experiment was a three year project to improve our structural and petrologic knowledge of the lithosphere and to test the hypothesis that the lithospheric structure produced during assembly of southwestern North America has profoundly influenced physical and chemical modification of the continental lithosphere during all subsequent magmatic and tectonic events, including those related to the ongoing asthenospheric flow. The principal investigators studied two Proterozoic structures with a range of seismic and geologic methods: the Cheyenne Belt and the Jemez lineament. Reflection, refraction, and teleseismic investigations are providing crustal - and lithospheric - scale images of major structures. A more complete picture of the evolution of the lithosphere has been added by geologic studies of Precambrian shear zones and Phanerozoic structures, xenolith studies, and geomorphologic and exhumation studies of present landforms. Phase 1 brought together 18 investigators from 14 institutions, including collaboration with a German-funded refraction team. With these awards, one year of funding is provided to continue to process, interpret, and integrate the diverse data sets generated in Phase 1 and to begin developing geodynamic models. The Principal Investigators will also explore new methods of data integration towards the goal of developing a "master model" for lithospheric structure.***