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Constraining Plateau Uplift in Southern Africa by Combining Thermochronology, Sediment Flux, Topography, and Landscape Evolution Modeling
Journal of Geophysical Research: Solid Earth ( IF 3.9 ) Pub Date : 2021-07-02 , DOI: 10.1029/2020jb021243
Jessica R. Stanley 1 , Jean Braun 2, 3 , Guillaume Baby 4 , François Guillocheau 5 , Cécile Robin 5 , Rebecca M. Flowers 6 , Roderick Brown 7 , Mark Wildman 7 , Romain Beucher 8
Affiliation  

The uplift of the southern African Plateau with its average elevations of ∼1,000 m is often attributed to mantle processes, but there are conflicting theories for the timing and drivers of topographic development. Evidence for most proposed plateau development histories is derived from continental erosion histories, marine stratigraphic architecture, or landscape morphology. Here we use a landscape evolution model to integrate a large data set of low-temperature thermochronometry, sediment flux rates to surrounding marine basins, and current topography for southern Africa. We explore three main hypotheses for surface uplift: (a) southern Africa was already elevated by the Early Cretaceous before Gondwana breakup, (b) uplift and continental tilting occurred during the mid-Cretaceous, or (c) uplift occurred during the mid to late Cenozoic. We test which of these three intervals of plateau development are plausible by using an inversion method to constrain the range in erosional and uplift model parameters that can best reproduce the observed data. Results indicate four regions of parameter space that fall into two families of uplift histories are most compatible with the data. Both uplift families have limited initial topography with some topographic uplift and continental tilting starting at ∼90–100 Ma. In one acceptable scenario, nearly all of the topography, >1,300 m, is created at this time with little Cenozoic uplift. In the other acceptable scenario, ∼400–800 m of uplift occurs in the mid-Cretaceous with another ∼500–1,000 m of uplift in the mid-Cenozoic. The two model scenarios have different geodynamic implications, which we compare to geodynamic models.

中文翻译:

通过结合热年代学、沉积物通量、地形和景观演化建模来限制南部非洲的高原隆升

南部非洲高原平均海拔约 1,000 米的隆起通常归因于地幔过程,但关于地形发展的时间和驱动因素存在相互矛盾的理论。大多数提出的高原发展历史的证据来自大陆侵蚀历史、海洋地层结构或景观形态。在这里,我们使用景观演化模型来整合大量的低温热测时数据集、周围海洋盆地的沉积物通量率以及南部非洲的当前地形。我们探讨了地表隆升的三个主要假设:(a) 南部非洲在冈瓦纳大陆分裂之前已经被早白垩世抬升,(b) 在白垩纪中期发生隆起和大陆倾斜,或 (c) 隆起发生在中晚期新生代。我们通过使用反演方法来限制能够最好地再现观测数据的侵蚀和隆起模型参数的范围,来测试这三个高原发展间隔中的哪一个是合理的。结果表明,属于两个隆起历史家族的四个参数空间区域与数据最兼容。两个隆起族都具有有限的初始地形,在~90-100 Ma 开始有一些地形隆起和大陆倾斜。在一种可接受的情况下,几乎所有的地形(>1,300 m)都是在此时创建的,新生代几乎没有隆起。在另一种可接受的情况下,约 400-800 米的隆起发生在白垩纪中期,另外约 500-1,000 米的隆起发生在中新生代。这两种模型情景具有不同的地球动力学含义,我们将其与地球动力学模型进行比较。
更新日期:2021-07-16
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