SGER: Interactions Of Hotspots and the Lithosphere: An Integrated Study of the Newberry Hotspot

SGER：热点与岩石圈的相互作用：纽伯里热点的综合研究

• 批准号: 0539987
• 负责人: Richard Allen
• 金额: $ 2万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-15 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0539987&HistoricalAwards=false
• 关键词: SGER; Interactions; Hotspots; Lithosphere; Integrated

A crucial and unsolved question in global earth science is the relationship of hotspots toprocesses that occur in the mantle beneath them. The most prevalent model for the formation of hotspots is the mantle plume model (stationary deep-mantle source) and, consequently, many previous studies have focused on classic plume locations. The PI will address the cause of the Newberry hotspot track in Oregon which cannot be the product of a stationary mantle source. The three end-member tectonic models for the formation of the Newberry hotspot are: (1) gravitational flow along the base of the continental lithosphere due to the edge of the craton or plume related material, (2) counterflow associated with subduction of the Juan de Fuca plate, and (3) progressive lithospheric faulting at the northern boundary of the Basin and Range. The preliminary seismic data suggest that there is no flow of mantle material along the length of the Newberry hotspot. Rather, E-W oriented shear wave splitting observations, oblique to the volcanic progression, are observed regionally. These observations suggest that either hypotheses (1) and (2) need modification or that lithospheric processes (hypothesis 3) exert thedominant control. The PI will utilize datasets from seven existing seismic networks to investigate lithospheric and asthenospheric structure in the region. Tomographic imaging of the mantle will integrate teleseismic body-wave traveltimes with local surface-wave constraints. The preliminary seismic anisotropy study will be extended to include more stations and the larger datasets that are becoming available. The ultimate goal of the proposal is to characterize the lithospheric and asthenospheric processes beneath the Newberry hotspot. These processes can then be used as a complementary hypothesis to the mantle plume model, in order to objectively evaluate other hotspots. The proposed analysis of the existing data sets in Oregon will provide a mechanism to optimize Earthscope resources through planning of future experiments to coincide with thepresence of the USArray transportable array and the arrival of PBO equipment in the region.

在全球地球科学中，一个关键而未解决的问题是热点与其下地幔中发生的过程之间的关系。热点形成的最流行的模型是地幔柱模型（固定深地幔源），因此，许多以前的研究都集中在经典的地幔柱位置。PI将解决俄勒冈州的纽贝里热点轨道的原因，该热点轨道不可能是固定地幔源的产物。形成纽贝里热点的三种端元构造模式是：（1）由于克拉通或地幔柱相关物质的边缘，重力流沿着大陆岩石圈底部，（2）与胡安德富卡板块俯冲有关的逆流，（3）在盆地和山脉的北方边界的岩石圈进行性断裂。初步的地震数据表明，沿着纽贝里热点的长度没有地幔物质的流动。相反，E-W方向的剪切波分裂观测，斜向火山的进展，观察区域。这些观测结果表明，要么假设（1）和（2）需要修改，要么岩石圈过程（假设3）发挥主导作用。PI将利用七个现有地震网络的数据集来调查该地区的岩石圈和软流圈结构。地幔的层析成像将把地幔体波走时与局部面波约束结合起来。初步的地震各向异性研究将扩大到包括更多的台站和越来越多的数据集。该建议的最终目标是描述纽贝里热点下岩石圈和软流圈过程的特征。这些过程可以作为地幔柱模型的补充假设，以便客观地评估其他热点。拟议的对俄勒冈州现有数据集的分析将提供一种机制，通过规划未来的实验来优化Earthscope资源，以配合USAray可移动阵列的存在和PBO设备在该地区的到来。