Studies of mantle flow and evolution

拟议的研究解决了理解固体地球的演化和现状的中心问题之一：地球是否？S地幔是整体对流，还是由单独的对流层组成。这决定了来自地球的物质的交流程度。从最深处到地表。迄今为止，来自地球化学、地震学和地球动力学的证据得出了相互矛盾的结论，一个重要的考虑因素涉及深部地幔的高粘度。本提案旨在发展和研究地球的对流和热演化模型及其对地幔黏度分层的依赖，以及板块构造的某些方面。结果将包括对地球历史上来自下地幔的热量和质量传输的估计，以及它对模型各种参数的依赖。这将与基于稀有气体同位素测量的地球化学模型的估计进行比较，稀有气体同位素测量限制了下地幔质量。这些模型将基于质量和能量守恒的参数化处理，并将得到验证。反对数值计算。它们将使更详细的数值计算结果能够在控制参数和特征（如可变板几何）的不确定性背景下被理解。该模型还将处理地球上对流和板块构造的三维性质所产生的一些影响。这些模型的预期结果将有助于理解地球的演化及其内部状态，以及诸如是否需要在地幔深处存在未被发现或隐藏的层等问题。它还将有助于理解地球上对流和板块构造的时间变异性，并估计地球长期演化的当前状态的代表性。

The proposed research addresses one of the central problems in understanding the evolution and current state of the solid Earth: Whether the Earth?s mantle convects as a whole, or whether it is composed of separately convecting layers. This determines the extent of communication of material from the Earth?s deepest interior to the surface. Evidence from geochemistry, seismology and geodynamics has so far produced contradictory conclusions, and an important consideration involves the high viscosity of the deeper mantle. This proposal is to develop and investigate models of convection and the thermal evolution of the Earth and its dependence on viscosity layering in the mantle, as well as on some aspects of plate tectonics. The results will include estimates of the heat and mass transport from the lower mantle over Earth history, as well as its dependence of various parameters of the model. This will be compared with estimates from geochemical models based on noble gas isotopic measurements that constrain the lower mantle mass flux. The models will be based on parameterized treatments of mass and energy conservation, and will be verified against numerical calculations. They will allow the results of more detailed numerical calculations to be understood in the context of uncertainties in the governing parameters and features such as variable plate geometry. The model will also address some effects that arise from the three dimensional nature of convection and plate tectonics on the Earth. The expected results of the models will contribute to the understanding of the evolution of the Earth and its internal state, and questions such as whether or not there is a need for undiscovered or hidden layers deep in the mantle. It will also help to understand the temporal variability of convection and plate tectonics on the Earth, and estimate how representative the present state is of the longer term evolution of the Earth.