Collaborative Research: Northwestern Canada Seismic Experiment

加赫蒂-EAR 0003404 Revenaugh-0003746 Garnero-0003745加拿大西北实验（以下简称CANOE）将采用一个Y形的48站宽带地震阵列，以解决固体地球演化过程中两个尚未解决的重大问题：大陆的集结和稳定，以及地核-地幔边界（CMB）作为地幔柱的发源地和俯冲板块的墓地的重要性。 大陆是通过与俯冲有关的一系列碰撞事件构造的，大陆从快速稳定的核向外生长，在随后的数十亿年中几乎没有变形。 这种稳定性可能是由于与克拉通建设相关的动态过程，但知之甚少。世界上绘制大陆构造图的最佳地点是加拿大地盾的西北角，其特征是从25 - 40亿年前的奴隶省（地球上已知最古老的岩石所在地）到最近隆起的北方科迪勒拉山脉。 调查人员将在这一过渡过程中部署宽带地震仪，西部的一条手臂沿着阿拉斯加高速公路从不列颠哥伦比亚省的怀特霍斯到AB省的埃德蒙顿，东部的一条手臂从不列颠哥伦比亚省的纳尔逊堡到西北地区的耶洛奈夫。 利用当地、区域和远距离地震的记录，调查人员将构建与这一科迪勒拉到克拉通过渡有关的地幔和地壳的详细图像。通过记录太平洋盆地远距离的地震，CANOE部署还将提供最低地幔地震结构的无与伦比的采样。90年代见证了一系列关于地球下地幔和CMB的新的和不寻常的发现，包括成分不均匀性，部分熔融和各向异性地幔结构的证据，这些证据对地幔动力学过程有很强的影响。加拿大位于世界上绝大多数深地震活动的120度范围内，提供了一个更详细地研究下地幔的绝佳机会。 这包括对夏威夷下面的CMB的无与伦比的覆盖，提供了一个极好的机会来测试这个热点原型的起源模型。在实验之后，所有数据将通过IRIS数据管理中心（www.iris.washington.edu）向社区提供。 IRIS PASSCAL计划将提供地震仪器。 该实验的一部分由加拿大Lithoprobe计划通过向不列颠哥伦比亚省大学提供赠款资助。

Gaherty-EAR0003404Revenaugh-0003746Garnero-0003745The Canadian Northwest Experiment (CANOE hereafter) will employ a Y-shaped, 48-station broadband seismic array to address two of the great unsolved problems in the evolution of the solid Earth: the assembly and stabilization of the continents, and the importance of the Earth's core-mantle boundary (CMB) as the birthplace of mantle plumes and the graveyard of subducted slabs. Constructed via a sequence of collisional events associated with subduction, continents grow outwards from nuclei that stabilize quickly, experiencing little deformation over the subsequent billions of years. This stability is presumably due to dynamic processes associated with craton construction, but is poorly understood. The best locale in the world for mapping continent construction is the northwestern corner of the Canadian shield, which is characterized by a progression from the 2.5-4 billion-year-old Slave province (home to the oldest known rocks on Earth) to the recently uplifted Northern Cordillera of the great Rocky Mountain system. The investigators will deploy broadband seismometers across this transition, with a western arm following the Alaskan highway from Whitehorse, BC to Edmonton, AB, and an eastern arm reaching from Fort Nelson, BC to Yellowknife, NWT. Using records of local, regional, and distant earthquakes, the investigators will construct detailed images of the mantle and crust associated with this cordillera-to-craton transition.By recording earthquakes from the far reaches of the Pacific basin, the CANOE deployment will also provide unsurpassed sampling of the seismic structure of the lowermost mantle. The 90's witnessed a parade of new and unusual discoveries about the Earth's lower mantle and CMB, including evidence for compositional heterogeneity, partial melting, and anisotropic mantle fabric that have strong implications for mantle dynamic processes. CANOE, situated within 120o of the vast majority of the world's deep seismicity, provides a remarkable opportunity to examine the lower mantle in greater detail. This includes unsurpassed coverage of the CMB beneath Hawaii, providing an excellent opportunity to test models of the genesis of this hotspot archetype.Following the experiment, all data will be made available to the community through the IRIS Data Management Center (www.iris.washington.edu). Seismic instrumentation will be provided by the IRIS PASSCAL program. A portion of the experiment is funded by the Canadian Lithoprobe program via a grant to the University of British Columbia.--