A Detailed Mapping of Uppermost Mantle Pn Velocities in Western North America and Other Continental Regions Located Behind Convergent Plate Boundaries

北美西部和汇聚板块边界后面的其他大陆区域最上地幔 Pn 速度的详细绘图

• 批准号: 8707035
• 负责人: Muawia Barazangi
• 金额: --
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-08-01 至 1990-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8707035&HistoricalAwards=false
• 关键词: Detailed; Mapping; Uppermost; Mantle; Pn

We propose to map in detail uppermost mantle Pn velocities beneath western North America and other elevated continental regions located behind convergent plate boundaries, such as the Tibetan, Turkish-Uranian, and the Altiplano-Puna plateaus on a scale comparable to the major tectonic provinces. This mapping will provide critical constraints on the structure and origin of continental plateaus. Such results can be used to answer an ongoing debate over the "double" Moho beneath the Great Basin. We propose to use the massive digital ISC data in a simple but effective way to obtain thousands of Pn velocity determinations, which will be based on the reports of Pn arrival times from about ten thousand events recorded at hundreds of seismic stations in western North America. We plan to use the two- station method in which the source is located at epicentral distances where Pn is the first arrival and the source is in, or very near, the azimuth of the two-station pair. The station pairs are selected to be within definable tectonic provinces. A pilot study to map Pn velocity beneath the Colorado plateau produced very encouraging results with about a thousand Pn velocity determinations. We plan to extend our efforts to the rest of the provinces in western North America, and to other elevated continental regions located behind convergent plate boundaries. We also propose to use all available Pn velocities and source and station delays, using the procedure of Hearn and Clayton. Because of the large variations in the spatial distribution of stations and sources, the resolution of this method may vary from one province to another. The combined results of the two-station and tomography methods will provide a detailed map of uppermost mantle velocities.

我们建议详细地绘制上地幔Pn速度 在北美西部和其他大陆的 位于会聚板块边界之后的区域，例如 西藏，土耳其-乌拉尼亚和高原-普纳高原， 规模可与主要构造省相媲美。 该映射 将对结构和起源提供关键约束 大陆高原。 这样的结果可以用来回答一个 关于大盆地下“双重”莫霍面的争论仍在继续。 我们建议使用大量的数字ISC数据， 获得数千个Pn速度测定的有效方法， 其将基于来自以下的Pn到达时间的报告： 在数百个地震记录中， 北美西部的车站。 我们计划用这两个- 震源位于震中的测站法 Pn是首次到达且源在其中的距离， 或者非常接近两站对的方位角。 车站 对被选择为在可定义的构造省内。 绘制科罗拉多高原下Pn速度图的初步研究 产生了非常令人鼓舞的结果， 速度测定 我们计划将我们的努力扩大到 北美西部的其他省份，以及其他 位于会聚板块后面的隆起大陆区域 边界 我们还建议使用所有可用的Pn速度 以及源和站延迟，使用Hearn和 克莱顿。 由于空间上的巨大变化， 站点和源的分布， 方法可能因省而异。 将合并的 两站和层析成像方法的结果将提供 上地幔速度的详细地图