Linking the deep structures of the cratons of Africa and South America by integrated geophysical modelling

通过综合地球物理模型连接非洲和南美洲克拉通的深层结构

• 批准号: 336717379
• 负责人: Professor Dr. Jörg Ebbing
• 金额: --
• 依托单位: Sektion 1.3: Erdsystem-Modellierung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/336717379?language=en
• 关键词: Linking; deep; structures; cratons; Africa; Linking; deep; structures; cratons; Africa

In the proposed study, we are going to integrate gravity, seismic, geothermal and mineral physical data for investigations of the lithosphere of the regions of Africa and South America. For both continents, compositional changes reflecting the tectonothermal age have been proposed previously, which largely affect geophysical observables as seismic velocities and densities. The comparison between the continents allows to decipher the similarities and differences in the evolution of the cratonic interior.Analysis of a single geophysical technique does not allow to distinguish clearly between compositional and additional thermal effects in the upper mantle. Furthermore, sources in the crust limit the detection of upper mantle sources, especially in gravity studies. For the two regions, crustal models exist from seismic and seismological studies and we will make use of the newly available gravity gradients from the GOCE satellite mission. Satellite gravity gradients have the advantage that their main sensitivity is limited to a depth of less than 100 km, so they can be used to validate the density structure in the (lower) crust and upper mantle. The novel data set allows further to discriminate with a higher confidence than in previous studies between lithospheric and sub-lithospheric components in the gravity field. The gravity residuals are then exploited to estimate dynamic topography and the role of mantle dynamics on the present state of the cratonic interior, e.g the evolution of sedimentary basins, of the continents. In addition, the results will be used to model mantle flow by converting the temperature variations to viscosity variations, while the density heterogeneity drives convection. Models of mantle flow velocities will be established that are analysed jointly with the obtained structural models to characterize the processes that affect the compositional structure of the lithosphere.

在拟议的研究中，我们将整合重力，地震，地热和矿物质物理数据，以研究非洲和南美地区的岩石圈。对于两个大洲，以前已经提出了反映构造体热时代的组成变化，这在很大程度上影响了地球物理可观察到的地震速度和密度。大陆之间的比较允许破译克拉通内部演化的相似性和差异。单个地球物理技术的分析不允许在上层地幔中清楚区分成分和其他热效应。此外，地壳中的来源限制了上地幔源的检测，尤其是在重力研究中。对于这两个区域，地壳模型来自地震和地震学研究，我们将利用Goce卫星任务中新近可用的重力梯度。卫星重力梯度的优势是它们的主要灵敏度仅限于100 km的深度，因此可以用于验证（下）地壳和上层地幔中的密度结构。与先前在重力场中岩石圈和亚地圈成分之间的研究相比，新型数据集可以进一步以更高的置信度区分。然后将重力残差利用以估计动态形态以及地幔动力学对当前cratonic内部状态的作用，例如，大陆沉积盆地的演变。此外，结果将用于通过将温度变化转换为粘度变化来模拟地幔流，而密度异质性驱动对流。将建立地幔流速度的模型，并与获得的结构模型共同分析，以表征影响岩石圈组成结构的过程。