How is topography maintained in the western Himalayan and where is plate convergence accommodated?

尽管在了解板块运动如何在收敛的板块边界处被调节方面取得了重大进展，但造山锋面的地形是如何维持的，以及板块收敛的确切位置是在哪里划分的，仍然存在争议。这反映在经常相互矛盾的短期和长期推导出的地壳缩短率及其在山脉锋面地震构造分割的背景下的解释上，这一问题可能与造山楔变形的时空变化密切相关。这种完全不同的活动水平是系统的还是随机过程引发的？回答这个问题对于理解楔块变形的机制和位置及其时间至关重要，这对于在构造活跃的山脉中减轻灾害和减少风险是最终必要的。解决这一问题，在中间时间尺度上获取变形速率和测量断层位置是评估变形机制和地震模式以及破译地震重现模式的关键任务。喜马拉雅山脉是由一堆逆冲板构成的，即造山楔，当印度俯冲到西藏下面时，从印度刮出。所有主要断裂系统内的楔底都进入喜马拉雅主逆冲（MHT），是主要的基底褶皱。相互竞争的假说认为，喜马拉雅地形是持续的，板块汇聚是由单独沿着基底的变形或通过跨越多个逆冲断层的更广泛分布的变形来调节的。然而，这两种假设都可能是正确的，因为随着时间的推移，这些端元情景可能是造山楔活动的特征，这取决于造山楔的临界程度，而造山楔的临界程度从根本上受推进冲断层的吸积和侵蚀的影响。根据我以前在该地区的工作，我假设喜马拉雅楔的构造可能确实遵循两种端部变形风格之间的模式。气候和侵蚀的时空变化在整个喜马拉雅锋面上形成了普遍存在的晚更新世和全新世河流阶地。这些地貌特征在西喜马拉雅（东经73°至80°）保存完好，因此使该地区成为量化阶地形成时间和瞬时泥沙负荷、阶地废弃和变形的主要区域。在这里，我建议量化地壳缩短、晚更新世沉积负荷、晚更新世和全新世断层位移率和侵蚀之间的潜在联系和相互作用。我们的最终目标是量化造山楔动力学背景下山前变形的时空特征。

Despite major advances in understanding how plate motion is accommodated at convergent plate boundaries, it is still controversially debated how topography of orogenic fronts is sustained and where exactly plate convergence is partitioned. This is reflected by frequently contradictory short- and long-term derived crustal shortening rates and their interpretation in the context of the seismotectonic segmentation of range fronts - a problem that may be intimately associated with temporal and spatial variations of deformation in orogenic wedges. Are such disparate levels of activity systematic or are they triggered by random processes? Answering this question is fundamental for understanding the mechanisms and loci of wedge deformation and its timing, which is ultimately necessary for hazard mitigation and risk reduction in tectonically active mountain ranges. To address this problem obtaining deformation rates and measuring the locus of faulting on intermediate timescales is a key task to assess the deformation mechanisms and earthquake patterns and to decipher earthquake recurrence patterns.The Himalaya constitutes a stack of thrust sheets, i.e. the orogenic wedge, scraped off India as it is subducted beneath Tibet. All primary fault systems within the wedge sole into the Main Himalayan Thrust (MHT), the main basal décollement. Competing hypotheses suggest that Himalayan topography is sustained and plate convergence is accommodated by deformation either solely along the basal décollement or through more broadly distributed deformation across multiple thrust faults. However, both hypotheses could be true as orogenic wedge activity may be characterized by these end-member scenarios over time, depending on the criticality of the orogenic wedge, which is fundamentally influenced by accretion and erosion in the advancing thrusts.Based on my previous work in the region I hypothesize that the tectonics of the Himalayan wedge may indeed follow a pattern between two end-member deformation styles. The temporal and spatial variations in climate and erosion have generated ubiquitous Late Pleistocene and Holocene fluvial terraces across the entire length of the Himalayan front. The excellent preservation of these geomorphic features in the western Himalaya (73°E to 80°E), thus makes this region a prime area to quantify the timing of terrace formation and transient sediment loading, terrace abandonment and deformation. Here I propose to quantify potential links and interactions between crustal shorting, late Pleistocene sedimentary loading, Late Pleistocene and Holocene fault displacement rates, and erosion. Our ultimate goal is to quantify the spatial and temporal characteristics of mountain-front deformation in the context of orogenic wedge dynamics.