Collaborative Research: Lithospheric Structure and Evolution of the Rocky Mountain Transect of the Western U.S.: An Integrated Geological and Geophysical Investigation

这项合作研究的目的是了解北美西南部落基山脉样带岩石圈的演化。该样带位于两个全球独特的构造体系的结合处，每一个都对理解大陆构造具有重要意义，并且共同代表了大陆岩石圈研究的杰出野外实验室。首先，一条1000 km宽的幼元古代造山带记录了1.8 - 1.6 Ga之间地幔源的大陆物质沿ne向边界快速增生并组装到南劳伦西亚。其次，目前西南地区的高海拔，特别是落基山脉，是Laramide、第三纪和元古代岩石圈仍在进行的改造的表现，这种改造导致了大陆内部古老、寒冷、高速的地幔和美国西部较热、低速的地幔之间有一个广泛的北西向的地幔边界带。私家侦探们希望更好地了解岩石圈演化过程中“主动”和“被动”过程之间的相互作用。他们的主要假设是，在美国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中，深刻地影响了大陆岩石圈的物理和化学变化，包括那些与正在进行的小规模软流圈对流重组和软流圈取代岩石圈有关的事件。为了验证这一假设，他们提出了一套综合的多尺度实验，使用最先进的地球物理、地质和地球化学技术，这些技术一起被设计用来破译岩石圈结构和演化，以及岩石圈形成和变形的过程

9614638WillettThis collaborative study is aimed at understanding the evolution of the lithosphere of the Rocky Mountain transect in the North American southwest. This transect is located at the juncture of two globally-unique tectonic regimes, each of fundamental importance for understanding continental tectonics and together representing an outstanding field laboratory for studies of continental lithosphere. First, a 1000 km wide juvenile Proterozoic orogenic belt records rapid accretion of continental materials from mantle sources and their assembly to southern Laurentia along NE-trending boundaries between 1.8 and 1.6 Ga. Second, the present high elevation of the SW in general and the Rocky Mountains in particular, is the manifestation of Laramide, Tertiary, and still ongoing modification of Proterozoic Lithosphere that has resulted in a wide NW-trending mantle boundaray zone between old, cold, high velocity mantle in the continental interior and hotter, lower velocity mantle in the western U.S. By examining the present-day lithospheric structure across ancient boundaries, the P.I.s hope to better understand the interplay between "active" and "passive" processes during lithospheric evolution.Their principal hypothesis is that lithospheric structures produced during assembly of the southwestern U.S. have profoundly influenced physical and chemical modification of the continental lithosphere during all subsequent magmatic and tectonic events, including those related to the ongoing reorganization of small-scale asthenospheric convection and replacement of lithosphere by asthenosphere. To test this hypothesis, they propose an integrated set of multi-scale experiments using state-of-the-art geophysical, geological and geochemical techniques that, together, are designed to decipher lithosphere structure and evolution, and processes of lithosphere formation and deformation.***