Studies of mantle flow and evolution

地幔流动与演化研究

• 批准号: 1015353
• 负责人: Richard O'Connell
• 金额: $ 22.5万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1015353&HistoricalAwards=false
• 关键词: Studies; mantle; flow; evolution

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.

拟议中的研究解决了理解固体地球演化和当前状态的核心问题之一：地球是否？的地幔作为一个整体对流，或是否它是由单独的对流层。这就决定了地球物质的交流程度？它的内部最深处。迄今为止，来自地球化学、地震学和地球动力学的证据产生了相互矛盾的结论，一个重要的考虑因素涉及更深地幔的高粘度。这项建议是要发展和研究地球的对流和热演化模型及其对地幔粘性分层的依赖性，以及对板块构造的某些方面的依赖性。结果将包括估计的热量和质量输运从下地幔在地球历史上，以及它的依赖模型的各种参数。这将与基于稀有气体同位素测量的地球化学模型的估计值进行比较，这些模型限制了下地幔质量#64258;ux。该模型将基于质量和能量守恒的参数化处理，并将根据数值计算进行艾德。他们将允许更详细的数值计算的结果被理解的背景下的不确定性的管理参数和功能，如可变板的几何形状。该模型还将解决对流和地球上的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了解地球的演变及其内部状态，以及是否需要在地幔深处发现未被发现或隐藏的层等问题。它还将有助于理解对流和地球板块构造的时间变化，并估计目前的状态对地球长期演化的代表性。