Modelling and prediction of dynamical impact of mantle convection on global surface processes

地幔对流对全球表面过程的动力学影响的建模和预测

• 批准号: 217272-2008
• 负责人: Forte, Alessandro
• 金额: $ 3.46万
• 依托单位: Université du Québec à Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=477965
• 关键词: Modelling; prediction; dynamical; impact; mantle

The heat engine inside the rocky mantle below Earth's crust is characterised by the very large scale transport of mass and heat across vertical and horizontal distances of thousands of kilometres inside our planet. This continuous flow of hot rock, termed thermal convection, exerts forces which drive the horizontal 'drift' of the surface tectonic plates, generating deformations in the crust which are relaxed by large, often destructive earthquakes. These deep Earth forces also produce vertical displacements of the continents and ocean floor across distances of hundreds of metres, thereby producing relative sea level variations which have indundated large portions of continental interiors in the geologic past. These vertical movements can also change the external shape of the Earth to such an extent that they perturb its orbital inclination relative to the Sun and can thus affect the evolution of climate cycles on our planet. In this proposal we provide an ambitious and exciting series of new initiatives to directly model and predict the dynamical impact of mantle convection on these wide ranging surface processes which have shaped the evolution of Earth's surface environment over geological time spans. Through refinements of numerical convection codes which we are developing to reconstruct the evolution of Earth's interior in the geologic past, we will model fundamental dynamical processes affecting two continents in particular, North America and Africa, and these include: (1) dynamic surface topography and erosion; (2) (in)stability of coastal margins and sea level variations; (3) surface stress patterns and earthquake activity. Using these convection models we will also make detailed predictions of the global-scale changes of Earth's external shape and rotation variations over the past 60 million years, thus providing new insights on how mantle convection may affect Earth's palaeoclimate cycles. We will also seek to substantially improve our knowledge of the 3-D mantle structure by carrying out a new series of joint inversions of global seismic and convection data. These innovative investigations into the workings of the Earth System will be advanced by the participation and training of HQP and through multiple international collaborations which we will foster.

地壳下方岩石地幔内的热机的特点是在地球内部数千公里的垂直和水平距离上进行大规模的质量和热量传输。这种热岩的连续流动（称为热对流）所施加的力驱动地表构造板块的水平“漂移”，从而在地壳中产生变形，而这种变形在大的、通常是破坏性的地震中得到缓解。这些深层地球力还会使大陆和海底产生数百米的垂直位移，从而产生相对海平面变化，在地质过去淹没了大陆内部的大部分地区。这些垂直运动还可以改变地球的外部形状，从而扰乱地球相对于太阳的轨道倾角，从而影响地球气候周期的演变。在这项提案中，我们提供了一系列雄心勃勃且令人兴奋的新举措，以直接模拟和预测地幔对流对这些广泛的表面过程的动态影响，这些过程塑造了地球表面环境在地质时间跨度上的演变。通过改进我们正在开发的数值对流代码，以重建地质过去地球内部的演化，我们将模拟影响两个大陆（特别是北美和非洲）的基本动力过程，其中包括：（1）动态表面地形和侵蚀; (2) 沿海边缘和海平面变化的稳定性； (3)地表应力模式与地震活动。利用这些对流模型，我们还将对过去6000万年来全球范围内地球外部形状的变化和自转变化进行详细预测，从而为地幔对流如何影响地球古气候循环提供新的见解。我们还将通过对全球地震和对流数据进行一系列新的联合反演，寻求大幅提高我们对 3D 地幔结构的了解。这些对地球系统运作方式的创新研究将通过总部的参与和培训以及我们将促进的多项国际合作来推进。