Determination of Intensity of Earth's Magnetic Field During the Cretaceous and Tertiary Using Dated Chinese Basalts

利用定年中国玄武岩测定白垩纪和第三纪地球磁场强度

• 批准号: 9706439
• 负责人: Xixi Zhao
• 金额: $ 14.07万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-06-01 至 1999-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9706439&HistoricalAwards=false
• 关键词: Determination; Intensity; Earth; Magnetic; Field

9706439 Zhao Measurements of the intensity of the Earth's magnetic field in the past are critical for understanding the processes in the core that give rise to the Earth's magnetic field, and how and why the Earth's magnetic field reverses polarity. In addition, variation of the intensity of the Earth's magnetic field over geologic time may signal modulation of dynamo action in the core by the convective state of the lower mantle, and thus could also carry information about the rates of sea-floor spreading, hot-spot volcanism and Earth's tectonic cycle. The PIs propose studies of two important geophysical problems which are currently debated: (1) to obtain mid-Cretaceous paleointensities (91 Ma) to examine the question of intensity of the geomagnetic field during the Cretaceous Superchron, in particular whether the field was persistently low or unusually high during times of low reversal rate; (2) to determine the paleointensity from 7 Ma and 32 Ma old basalts to test whether the field strength is responsible for the relatively higher amplitude of marine magnetic anomalies that is observed in most of the world's oceans between 30 and 80 Ma. ***

9706439 赵 过去地球磁场强度的测量对于理解地核中产生地球磁场的过程以及地球磁场如何以及为何反转极性至关重要。此外，地球磁场强度随地质时间的变化可能会发出下地幔对流状态对地核发电机作用的调制信号，因此也可能携带有关海底扩张速率、热膨胀速率的信息。发现火山活动和地球的构造循环。 PI建议研究目前有争议的两个重要的地球物理问题：（1）获取白垩纪中期古强度（91 Ma），以研究白垩纪超年代期间地磁场的强度问题，特别是磁场是否持续较低或在低逆转率期间异常高； (2)确定7 Ma和32 Ma古老玄武岩的古强度，以测试场强是否是导致世界大部分海洋在30至80 Ma之间观测到的海洋磁异常相对较高幅度的原因。 ***