Retrodiction Range of geodynamic earth models from twin experiments that account for model inconsistencies and limited resolution of present-day heterogeneity

来自孪生实验的地球动力学地球模型的回顾范围，解释了模型不一致和当今异质性的有限分辨率

• 批准号: 412338397
• 负责人: Professor Dr. Hans-Peter Bunge, Ph.D.
• 金额: --
• 依托单位: Department für Geo- und Umweltwissenschaften
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/412338397?language=en
• 关键词: Retrodiction; Range; geodynamic; earth; models

Retrodictions with the adjoint method are a powerful tool to reconstruct past mantle states. They open new avenues to test dynamic earth models against a range of geologic and geophysical observables. So far, at a theoretical level their convergence and uniqueness properties have been elucidated only with highly simplified twin experiments, where the most severe limitation stems from the (unrealistic) assumption of perfect knowledge of the mantle convection parameters and the present-day model state. Here we propose to improve our fundamental understanding of mantle flow retrodictions studying (1) how inconsistent model parameters, compositional variations, and the limited resolving power of seismic inferences of the mantle state enter the retrodiction problem, (2) how the inconsistencies map into retrodicted mantle flow trajectories, and (3) how the trajectories contribute to growth of spurious heterogeneity as one goes back in time, effectively limiting the temporal range for which viable retrodictions can be achieved. To address these fundamental questions, we propose a systematic study of specifically designed twin experiments, where admissible parameter variations and seismic filtering effects are introduced systematically into the inverse problem, to estimate the impact on geodynamic retrodictions of: 1) deviations in rheological parameters between the reference and inverse model, 2) absence of small-scale structures in the mantle heterogeneity field due to tomographic filtering, 3) inconsistent interpretations of mantle buoyancies as a result of wrongful assumptions for the bulk composition, 4) errors in past plate motion models in particular related to the choice of reference frame point 3 will involve the derivation of a new set of adjoint equations capable of representing thermo-chemical convection.

利用伴随方法进行反演是恢复过去地幔状态的有力工具。他们开辟了新的途径，可以用一系列地质和地球物理观测数据来测试动态地球模型。到目前为止，在理论水平上，它们的收敛和唯一性仅通过高度简化的孪生实验来阐明，其中最严重的限制来自对地幔对流参数和当今模型状态的完美了解的(不现实的)假设。在这里，我们建议改进我们对地幔流动追溯的基本理解，研究(1)不一致的模型参数、成分变化和地幔状态地震推断的有限分辨率如何进入追溯问题，(2)不一致如何映射到追溯的地幔流动轨迹，以及(3)当一个人回到过去时，这些轨迹如何促进虚假不均质性的增长，从而有效地限制了可行追溯的时间范围。为了解决这些基本问题，我们建议对专门设计的孪生实验进行系统的研究，其中系统地将允许的参数变化和地震滤波效应引入到反问题中，以估计以下因素对地球动力学恢复的影响：1)参考模型和反模型之间的流变参数偏差，2)由于层析滤波而在地幔非均质场中没有小尺度结构，3)由于对主体成分的错误假设而导致对地幔浮力的不一致解释，4)过去板块运动模型中的误差，特别是与参考标架3的选择有关的误差，将涉及到推导一组新的能够表示热化学对流的伴随方程。