Numerical modeling of mantle flow, melt migration, and MORB compositions

地幔流、熔体迁移和 MORB 成分的数值模拟

• 批准号: 16337938
• 负责人: Professor Dr. Matthias Hort
• 金额: --
• 依托单位: Institut für Geophysik (IfG)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/16337938?language=en
• 关键词: Numerical; modeling; mantle; flow; melt

Volcanic activity at mid ocean ridges produces on average about 21 km3 of mid ocean ridge basalt (MORB) each year. These basalts have a fairly constant composition commonly known as MORB-composition. The heat flux at mid ocean ridge settings is found to be on the order of 500-1000 mW/m2. Small parts of the mid ocean ridges, however, show significant deviations from these average values. A particularly complex situation of an anomalously shallow and geochemically distinct section of the Mid-Atlantic ridge exhibiting an unusually high production of MORB is observed between the Ascension and Bode Verde fracture zones in the Southern Atlantic. This abnormal MORB is believed to be either caused by a weak mantle plume, proposed to be located underneath the ridge or at various distances from the ridge, or small-scale mantle heterogeneities. In the framework of this proposal we explore the possible fluid dynamic consequences of these scenarios for such an anomalous mid ocean ridge setting using a finite element code that is currently under development as well as dedicated analogue laboratory experiments. Our model calculations that will take into account various observations from other researchers of the SPP will help to hopefully tightly constrain which model (weak plume or small-scale mantle heterogeneities) is the most realistic for this mid ocean ride setting.

大洋中脊的火山活动平均每年产生约21千米的大洋中脊玄武岩(MORB)。这些玄武岩有一种相当稳定的成分，俗称MORB-成分。大洋中脊的热流密度在500-1000 mW/m~2量级。然而，大洋中脊的一小部分显示出与这些平均值的显著偏离。在南大西洋的阿森松和博德维德断裂带之间，观察到了一个特别复杂的情况，即大西洋中部海脊异常浅和地球化学不同的部分，显示出异常高的MORB产量。这种异常的MORB被认为要么是由位于海脊下方或距离海脊不同距离的弱地幔热柱引起的，要么是由于小尺度的地幔不均匀造成的。在这项提议的框架内，我们利用目前正在开发的有限元程序以及专门的模拟实验室实验，探讨了这些情景对这种异常的大洋中脊环境可能产生的流体动力学后果。我们的模型计算将考虑到来自SPP的其他研究人员的各种观测，有望有助于严格限制哪一种模型(弱羽流或小尺度地幔不均匀)对于这种中洋旅行环境最现实。