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1. Fault geometry, strain partitioning and deformation history inferred by fluvial topography and marine terraces analyses

   https://doi.org/10.1016/j.geomorph.2024.109583  

   Pavano, F (March 2025, Geomorphology)

   Advancements in the quantitative investigation of fluvial topography in tectonically active regions account for the emerging numerical modelling of river profiles and their linear inversions. Applications of a geomorphic approach strive for the reconstruction of long-term tectonic deformation histories by decoding base-level fall signals transiently embedded in the geomorphic record. I present integrated results from river profile inversions and marine terraces analyses, here used to outline the deformation model associated to a debated crustal fault system at the southern termination of the Calabrian Forearc High (Central Mediterranean). The study aims at constraining spatial and temporal variations in geometry, strain partitioning, slip rate, and time-transgressive propagation of the tectonic deformation associated with a fault system. In particular, I systematically analyze river profiles draining the eastern flank of the Peloritani Mts. in northeastern Sicily (southern Italy), a NNE-SSW- trending mountain ridge thought as located at the footwall of an active, ESE-dipping normal fault. I perform the linear inversions of fluvial topography by applying recently available MATLAB scripts, and I carry out the analysis of terraced surfaces by both GIS tools and MATLAB-based software packages. The results I obtain suggest that the eastern flank of the Peloritani Mts. have been deformed according to at least three main stages of uplift accommodated along distinct, ~10–15 km-long en-échelon arranged fault segments. The reconstructed evolution of tectonic deformation unveils time-transgressive, southward propagation since the last ~600 kyr, inset in a general increase, through time, of the regional component of uplift. The results of this study contribute to address the issues of the deformation style and strain partitioning along complex and/or debated fault systems. These results also demonstrate the potential of the geomorphic approach in defining the spatial and temporal tectonic evolutionary model of a region. 

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2. Structural analysis and tectonic evolution of the western domain of the Eastern Kunlun Range, northwest Tibet

   https://doi.org/10.1130/B35388.1  

   Wu, Chen; Liu, Changfeng; Fan, Suoya; Zuza, Andrew V.; Ding, Lin; Liu, Wencan; Ye, Baoying; Yang, Shijie; Zhou, Zhiguang (October 2019, GSA Bulletin)

   The Tibetan Plateau, the largest highland on Earth, formed due to the collision of India-Asia over the past 50−60 m.y., and the evolution of the Tibetan Plateau impacts our knowledge of continental tectonics. Examination of the northernmost margin of the Tibetan Plateau is key to unravelling the deformation mechanisms acting in northern Tibet. The left-slip Altyn Tagh fault system defines the northwest margin of the Tibetan Plateau, separating the Western and Eastern Kunlun Ranges in the southwest. Both Cenozoic and pre-Cenozoic crustal deformation events at this junction between the Altyn Tagh and Kunlun Ranges were responsible for the construction of northwestern Tibet, yet the relative contribution of each phase remains unconstrained. The western domain of the Eastern Kunlun Range is marked by active NE-trending, left-slip deformation of the Altyn Tagh fault and an E-striking Cenozoic thrust system developed in response India-Asia collision. To better constrain the Paleozoic Altyn Tagh and Kunlun orogens and establish the Cenozoic structural framework, we conducted an integrated investigation involving detailed geologic mapping (∼1:50,000 scale), U-Pb zircon geochronology, and synthesis of existing data sets across northwestern Tibet. Our new zircon analyses from Paleoproterozoic−Cretaceous strata constrain stratigraphic age and sediment provenance and highlight Proterozoic−Paleozoic arc activity. We propose a tectonic model for the Neoproterozoic−Mesozoic evolution of northwestern Tibet wherein restoration of an ∼56-km-long balanced cross section across the western domain of the Eastern Kunlun suggests that Cenozoic minimum shortening strain was ∼30% (∼24 km shortening). Field evidence suggests this shortening commenced after ca. 25−20 Ma, which yields an average long-term shortening rate of 1.2−0.9 mm yr−1 and strain rates of 4.7 × 10−16 s−1 to 2.3 × 10−16 s−1. Geometric considerations demonstrate that this contractional deformation did not significantly contribute to left-slip offset on the Altyn Tagh fault, which has ∼10 mm/yr slip rates. 

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3. Rock strength controls erosion in tectonically dead landscapes

   https://doi.org/10.1126/sciadv.adr2610  

   Haag, Mauricio B; Schoenbohm, Lindsay M; Wolpert, Joshua; Jess, Scott; Bierman, Paul; Corbett, Lee; Sommer, Carlos A; Endrizzi, Gabriel (January 2025, Science Advances)

   Interactions among tectonics, climate, and lithology shape the Earth’s surface. In regions dominated by tectonic quiescence and climate stability, the role of rock strength related to lithology, and its role in landscape evolution, can be most clearly perceived. We leverage these qualities in a unique field site by integrating topographic data, erosion rates, and a large suite of rock strength measurements to quantify the relationship between bedrock strength and erosion rates along a 200-km section of the southeast coast of Brazil where climatic and tectonic variability are minimal. Our findings reveal a 20-fold erosion rate variation best explained by differences in rock strength. We also demonstrate that incorporating lithological strength variability into the analysis of landscape incision substantially improves accuracy, with outcomes that better reproduce natural settings. Our results underscore the crucial role of rock strength in landscape evolution and emphasize the need for field studies to account for lithological variability and thus accurately interpret landscape dynamics. 

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4. Drainage network reorganization in landscapes buried by glacial deposits

   Kwang, Jeffrey S; Wickert, Andrew D; Larsen, Isaac J (December 2022, American Geophysical Union)

   For landscapes to achieve a topographic steady state, they require steady tectonic uplift and climate, and a bedrock that is uniformly erodible in the vertical direction. Basic landscape evolution models predict that incising drainage networks will eventually reach a static geometric equilibrium – that is, the map-view channel pattern will remain constant. In contrast, natural rivers typically incise through heterogeneous bedrock, which can force reorganization of the drainage structure. To investigate how lithological variability can force landscape reorganization, we draw inspiration from formerly glaciated portions of the upper Mississippi Valley. In this region, depth-to-bedrock maps reveal buried dendritic river networks dissecting paleozoic sedimentary rock. During the Pleistocene, ice advance buried the bedrock topography with glacial till, resurfacing the landscape and resetting the landscape evolution clock. As newly formed drainage networks develop and incise into the till-covered surface, they exhume the buried bedrock topography. This then leads to a geomorphic "decision point": Will the rivers follow the course of the bedrock paleodrainage network? Or will they maintain their new pattern? Using a numerical landscape evolution model, we find that two parameters determine this decision: (1) the contrast between the rock erodibility of the glacial till (more erodible) and of the buried sedimentary rock (less erodible) and (2) the orientation of the surface drainage network with respect to the buried network. We find that as the erodibility contrast increases, the drainage pattern is more likely to reorganize to follow the buried bedrock valleys. Additionally, as the alignment of the two networks increases, the surface drainage network also tends to restructure itself to follow the paleodrainage network. However, when there is less contrast and/or alignment, the surface drainage pattern becomes superimposed on the bedrock topography, with streams cutting across buried bedrock ridges. Our results agree with field studies demonstrating that variability in erodibility exerts a first-order control on landscape evolution and morphology. Our findings can provide insight into how lithologic variation affects surface processes, drives drainage reorganization, and creates geopatterns. 

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5. Quantifying Normal Fault Evolution from River Profile Analysis in the Northern Basin and Range Province, Southwest Montana, USA

   https://doi.org/10.2113/2021/7866219  

   Armstrong, Ian P.; Yanites, Brian J.; Mitchell, Nate; DeLisle, Clarke; Douglas, Bruce J. (April 2021, Lithosphere)

   Valla, Pierre (Ed.)

   Abstract Over the past few decades, tectonic geomorphology has been widely implemented to constrain spatial and temporal patterns of fault slip, especially where existing geologic or geodetic data are poor. We apply this practice along the eastern margin of Bull Mountain, Southwest Montana, where 15 transient channels are eroding into the flat, upstream relict landscape in response to an ongoing period of increased base level fall along the Western North Boulder fault. We aim to improve constraints on the spatial and temporal slip rates across the Western North Boulder fault zone by applying channel morphometrics, cosmogenic erosion rates, bedrock characteristics, and calibrated reproductions of the modern river profiles using a 1-dimensional stream power incision model that undergoes a change in the rate of base level fall. We perform over 104 base level fall simulations to explore a wide range of fault slip dynamics and stream power parameters. Our best fit simulations suggest that the Western North Boulder fault started as individual fault segments along the middle to southern regions of Bull Mountain that nucleated around 6.2 to 2.5 Ma, respectively. This was followed by the nucleation of fault segments in the northern region around 1.5 to 0.4 Ma. We recreate the evolution of the Western North Boulder fault to show that through time, these individual segments propagate at the fault tips and link together to span over 40 km, with a maximum slip of 462 m in the central portion of the fault. Fault slip rates range from 0.02 to 0.45 mm/yr along strike and are consistent with estimates for other active faults in the region. We find that the timing of fault initiation coincides well with the migration of the Yellowstone hotspot across the nearby Idaho-Montana border and thus attribute the initiation of extension to the crustal bulge from the migrating hotspot. Overall, we provide the first quantitative constraints on fault initiation and evolution of the Western North Boulder fault, perhaps the farthest north basin in the Northern Basin and Range province that such constraints exist. We show that river profiles are powerful tools for documenting the spatial and temporal patterns of normal fault evolution, especially where other geologic/geodetic methods are limited, proving to be a vital tool for accurate tectonic hazard assessments. 

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