True Polar Wander, Geotesselation and Earth Structure

真正的极地漫游、地理细分和地球结构

• 批准号: 8720730
• 负责人: David Stevenson
• 金额: $ 3.5万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-03-15 至 1990-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8720730&HistoricalAwards=false
• 关键词: True; Polar; Wander; Geotesselation; Earth

The Earth seeks to minimize its rotational energy while conserving angular momentum: the most striking predicted consequence of this is true polar wander (TPW). This proposal is to develop a systematic understanding of TPW and related rotational energy reduction affects, by a theoretical consideration of the following: (i) Geotesselation: What particular plate tectonic patterns (if any) are characteristic of the consequences of TPW? Can one, for example, understand the N-S trend of major subduction zones? (ii) Coupling: Does TPW require mutual ("locked") rotation of lithosphere and mantle or can these move separately? Preliminary work suggests that locked TPW is mandatory; a more complete analysis is needed. (iii) Is mantle circulation affected by earth rotation? Order-of-magnitude calculations suggest that the answer may be yes, at least to a modest degree. Linear stability analysis and approximate finite amplitude analyses are proposed to bolster or disprove this conjecture. (iv) What relationship, it any, is there between TPW and geomagnetic or paleomagnetic data? (v) Can we understand what particular circumstances favor or inhibit TPW of the real Earth?

地球寻求在保持角动量的同时最小化其自转能量：最引人注目的预测结果是真极移(TPW)。这一建议是为了通过以下理论考虑，对TPW和相关的旋转能量减少影响建立一个系统的理解：(I)地球迁移：TPW的后果有哪些特殊的板块构造模式(如果有的话)？例如，人们能理解主要俯冲带的N-S趋势吗？(2)耦合：TPW是否需要岩石圈和地幔的相互(“锁定”)旋转，或者它们是否可以分开运动？初步工作表明，上锁的TPW是强制性的；需要进行更完整的分析。(3)地幔环流是否受到地球自转的影响？数量级的计算表明，答案可能是肯定的，至少在一定程度上是这样。线性稳定性分析和近似有限幅分析被用来支持或反驳这一猜想。(4)TPW与地磁或古地磁数据之间有什么关系？(V)我们能否了解哪些特殊情况有利于或抑制真实地球的TPW？