Collaborative Research: Northwest Canada Seismic Experiment

Gaherty-EAR0003404Revenaugh-0003746Garnero-0003745The加拿大西北实验(以下简称CANOE)将使用一个Y形、48个台站的宽带地震阵列来解决固体地球演化中的两个重大悬而未决的问题：大陆的组装和稳定，以及地球核-地幔边界作为地幔羽流的发源地和俯冲板块的墓地的重要性。大陆由一系列与俯冲相关的碰撞事件构成，从快速稳定的原子核向外生长，在随后的数十亿年中经历了很小的变形。这种稳定性可能是由于与克拉通建造相关的动态过程，但人们对此知之甚少。世界上绘制大陆地图的最佳地点是加拿大地盾的西北角，它的特点是从25亿至40亿年前的奴隶省(地球上已知最古老的岩石的所在地)到最近隆起的伟大落基山脉系的北科迪勒拉。调查人员将在这一过渡期间部署宽带地震仪，西臂沿着阿拉斯加高速公路从公元前的怀特霍斯到阿肯色州的埃德蒙顿，东臂从公元前的纳尔逊堡延伸到西北部的耶洛奈夫。利用当地、区域和远距离地震的记录，研究人员将构建与科迪莱拉到克拉通过渡相关的地幔和地壳的详细图像。通过记录太平洋盆地远处的地震，独木舟的部署也将提供最低地幔地震结构的无与伦比的样本。90年代的S见证了一系列关于地球下地幔和CMB的新的和不同寻常的发现，包括对地幔动力学过程具有强烈意义的成分不均一性、部分熔融和各向异性地幔组构的证据。独木舟位于世界绝大多数深部地震活动的120度范围内，为更详细地研究下地幔提供了一个难得的机会。这包括对夏威夷海底CMB的无与伦比的报道，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)提供给社区。地震仪器将由IRIS PASSCAL程序提供。这项实验的一部分是由加拿大结石探测计划通过对不列颠哥伦比亚大学的资助来资助的。

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.--