Very-Long-Period Investigation of the Mantle Beneath the Canadian Shield: A Lakebottom Magnetotelluric Observatory

对加拿大地盾下地幔的长期调查：湖底大地电磁观测站

• 批准号: 8721223
• 负责人: Adam Schultz
• 金额: $ 9.99万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-03-15 至 1992-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8721223&HistoricalAwards=false
• 关键词: Very; Long; Period; Investigation; Mantle

A major feature of the plate tectonic model is the concept of a thermal boundary layer (TBL) at the earth's surface. This TBL serves as the upper boundary of the convective systems which drive the plate motions, and is dominated by a conductive thermal regime. Heat flow, subsidence, and other data have been used to argue for no significant differences between the deep structures under old ocean basins and old continents, both of which are at or very near a thermal equilibrium state. This suggests that the continental and oceanic lithospheres have the same thickness of about 150 km at equilibrium. Differences must exist in the upper lithosphere and crust to explain the buoyancy and mechanical behavior of continental material which helps govern its role in plate tectonics. A number of competing models for the deep structure of the continents have been proposed which will be tested by estimating the deep electrical conductivity structure beneath the Canadian Shield. The conductivity is a thermally activated process, and should be extremely sensitive to the radically different deep sub-shield mantle conditions associated with differing models of the continental lithosphere. The PIs will operate a very long period (VLP) magnetotelluric observatory in the bottom of a deep freshwater lake. This innovative deployment scheme overcomes many of the difficulties previously encountered in obtaining VLP MT data.

板块构造模型的一个主要特征是 地球表面的热边界层（TBL）。 此TBL 作为对流系统的上边界， 板块运动，并由一个传导热控制， 政权 热流、沉降和其他数据已被用于 认为深层结构之间没有显著差异 在古老的海洋盆地和古老的大陆之下， 或非常接近热平衡状态。 这表明 大陆和大洋岩石圈的厚度相同， 在平衡状态下大约150公里。 差异必须存在于上层 岩石圈和地壳解释浮力和机械 大陆材料的行为有助于控制其在 板块构造学 许多竞争车型的深 大陆的结构已经提出，这将是 通过估算深部电导率结构进行测试， 在加拿大地盾之下 电导率是一个热 激活的过程，并应非常敏感， 完全不同的深亚盾地幔条件 大陆岩石圈的不同模型。 法律与正义党 将运行一个甚长周期（VLP）大地电磁观测站 在一个很深的淡水湖底 这一创新 部署方案克服了许多困难，以前 在获取VLP MT数据时遇到的问题。