Description: Interpreting cooling ages from multiple thermochronometric systems and/or from steep elevation transects with the help of a thermal model can provide unique insights into the spatial and temporal patterns of rock exhumation. Although several well-established thermal models allow for a detailed exploration of how cooling or exhumation rates evolved in a limited area or along a transect, integrating large, regional datasets in such models remains challenging. Here, we present age2exhume, a thermal model in the form of a MATLAB or Python script, which can be used to rapidly obtain a synoptic overview of exhumation rates from large, regional thermochronometric datasets. The model incorporates surface temperature based on a defined lapse rate and a local relief correction that is dependent on the thermochronometric system of interest. Other inputs include sample cooling age, uncertainty, and an initial (unperturbed) geothermal gradient. The model is simplified in that it assumes steady, vertical rock uplift and unchanging topography when calculating exhumation rates. For this reason, it does not replace more powerful and versatile thermal–kinematic models, but it has the advantage of simple implementation and rapidly calculated results. We also provide plots of predicted exhumation rates as a function of thermochronometric age and the local relief correction, which can be used to simply look up a first-order estimate of exhumation rate. In our example dataset, we show exhumation rates calculated from 1785 cooling ages from the Himalaya associated with five different thermochronometric systems. Despite the synoptic nature of the results, they reflect known segmentation patterns and changing exhumation rates in areas that have undergone structural reorganization. Moreover, the rapid calculations enable an exploration of the sensitivity of the results to various input parameters and an illustration of the importance of explicit modeling of thermal fields when calculating exhumation rates from thermochronometric data.

Description: Drainage-divide migration, controlled by rock-uplift and rainfall patterns, may play a major role in the geomorphic evolution of mountain ranges. However, divide-migration rates over geologic timescales have only been estimated by theoretical studies and remain empirically poorly constrained. Geomorphological evidence suggests that the Sierra de Aconquija, on the eastern side of the southern Central Andes, northwest Argentina, is undergoing active westward drainage-divide migration. The mountain range has been subjected to steep rock trajectories and pronounced orographic rainfall for the last several million years, presenting an ideal setting for using low-temperature thermochronometric data to explore its topographic evolution. We perform three-dimensional thermal-kinematic modeling of previously published thermochronometric data spanning the windward and leeward sides of the range to explore the most likely structural and topographic evolution of the range. We find that the data can be explained by scenarios involving drainage-divide migration alone, or by scenarios that also involve changes in the structures that have accommodated deformation through time. By combining new 10Be-derived catchment-average denudation rates with geomorphic constraints on probable fault activity, we conclude that the evolution of the range was likely dominated by west-vergent faulting on a high-angle reverse fault underlying the range, together with westward drainage-divide migration at a rate of several km per million years. Our findings place new constraints on the magnitudes and rates of drainage-divide migration in real landscapes, quantify the effects of orographic rainfall and erosion on the topographic evolution of a mountain range, and highlight the importance of considering drainage-divide migration when interpreting thermochronometer age patterns.

Description: Alluvial rivers aggrade, incise, and adjust their sediment-transport rates in response to changing sediment and water supply. Fluvial landforms, such as river terraces, and downstream stratigraphic archives may therefore record information about past environmental change. Using a physically based model describing sediment transport and long-profile evolution of alluvial rivers, we explore how their responses to environmental change depend on distance downstream, forcing timescales, and whether sediment or water supply is varied. We show that amplitudes of aggradation and incision, and therefore the likelihood of terrace formation, are greater upstream and in shorter and/or wetter catchments. Aggradation and incision, and therefore terrace ages, may also lag behind environmental change. How sediment-transport rates evolve depends strongly on whether water or sediment supply is varied. Diverse responses to environmental change could arise in natural alluvial valleys, controlled by their geometry and hydrology, with important implications for paleo-environmental interpretations of fluvial archives.

Description: Major strike-slip fault systems on Earth, like the North Anatolian Fault (NAF), play an important role in accommodating plate motion, but surprisingly little is known about how such structures evolve through space and time. Along the central sector of the NAF in the Central Pontides, transpression and crustal thickening along the northward restraining bend of the fault are thought to have generated rock-uplift rates of 0.2–0.3 km/Myr since at least 400 ka based on Quaternary marine and river terraces, while data from low-temperature thermochronology suggest that an enhanced exhumation phase occurred within the last 11 Myr. However, the precise onset of this faster uplift phase, which likely reflects deformation associated with the development of the central sector of the NAF, is poorly constrained. Here we define the spatiotemporal pattern of rock-uplift rates within the Central Pontides over the last ∼10 Myr by performing linear inversions of 19 river profiles that drain the northern margin of the Central Pontides, from the Sinop Range to the Black Sea. We use 21 new 10Be-derived basin-average denudation rates to calibrate an erodibility parameter, which we use to convert our χ-transformed river profiles into rock-uplift histories. Our results document an increase in rock-uplift rates after 10 Ma, with peak rates of ∼0.15–0.25 km/Myr occurring between 4 and 2 Ma. Moreover, the spatiotemporal pattern of uplift suggests that faster rock uplift started in the eastern part of the Sinop Range and migrated westward over a period of ca. 2 to 2.5 Myr, which we relate to the westward propagation of the NAF through this sector at a rate of 74 ± 13 km/Myr. In the context of previously published constraints on the westward propagation of the NAF starting in eastern Turkey at ∼12 Ma, our results suggest differences in fault-propagation rates that coincide with differences in the orientation of the NAF relative to plate-convergence velocity vectors. Fault segments with higher obliquity appear to have propagated at rates up to 2-fold slower than those oriented more parallel to the plate-convergence vector.

Description: Himalayan rivers transport around a gigaton of sediment annually to ocean basins. Mountain valleys are an important component of this routing system: storage in these valleys acts to buffer climatic and tectonic signals recorded by downstream sedimentary systems. Despite a critical need to understand the spatial distribution, volume and longevity of these valley fills, controls on valley location and geometry are unknown, and estimates of sediment volumes are based on assumptions of valley-widening processes. Here we extract over 1.5 million valley-floor width measurements across the Himalaya to determine the dominant controls on valley-floor morphology and to assess sediment-storage processes. Using random forest regression, we show that channel steepness, a proxy for rock uplift, is a first-order control on valley-floor width. On the basis of a dataset of 1,148 exhumation rates, we find that valley-floor width decreases as exhumation rate increases. Our results suggest that valley-floor width is controlled by long-term tectonically driven exhumation rather than by water discharge or bedrock erodibility and that valley widening predominantly results from sediment deposition along low-gradient valley floors rather than lateral bedrock erosion.

Description: We the editors of Tectonics wish to express our sincere thanks to those of you who reviewed manuscripts for us in 2022. Science advances through open communication within the scientific community and trust in the integrity of scientific publications. Peer review is essential to scientific publication, helping to ensure that published work maintains the highest degree of rigor and integrity, is well communicated, accurately documented, appropriately placed in the context of prior work, and effectively archived for future usage. Considering our aim to ensure that all published work complies with FAIR data guidelines, we particularly appreciate the time reviewers have also spent on helping to improve data presentation and their suggestions for the best ways to ensure data reusability in the future. The 150 papers published in Tectonics in 2022 benefitted from the careful scrutiny and constructive criticism drawn from the expertise of 508 volunteer reviewers, who provided a total of 719 reviews. We thank you for helping Tectonics produce the high-quality output that has helped us maintain a prominent position in scientific publishing for decades, and for the spirit of teamwork that makes the peer review process an asset in our community.

Description: Die Landschaft, in der wir leben, ist nicht chaotisch, sondern effizient organisiert, auch wenn wir dies häufig nicht bemerken. Sie wird von einer natürlichen Architektin – Wasser – funktional gestaltet. Den Kräften der Gebirgsbildung stehen eine Reihe von wasserbetriebenen Werkzeugen gegenüber, die die Landschaft in einem dynamischen Gleichgewicht halten. In diesem Beitrag beleuchten wir einige Werke der Architektin Wasser, die das GFZ erforscht.

Description: The Himalaya is the largest mountain belt on Earth, stretching 2,500 km from the Nanga Parbat syntaxis in the northwest to the Namche Barwa syntaxis in the southeast. This chapter addresses three questions, using the observed topography and morphology of the mountain belt as well as inferred spatio-temporal variations in long-term erosion/exhumation rates to infer the kinematics of mountain building and the role of the Main Himalayan Thrust. It discusses the complementarity of this approach with geophysical datasets. The chapter provides a brief background to the methods used: quantitative geomorphic analysis, cosmogenic nuclides, thermochronology and thermo-kinematic modeling. It then reviews a number of case studies addressing different regions along the Himalayan arc: the western and central Nepal Himalaya, the latter of which has long been treated as the “type section” for Himalayan tectonics; the western Himalaya of northwest India; and the eastern Himalaya of Bhutan and Arunachal Pradesh.

Description: We explore the spatial and temporal variations in denudation rates in the northern Pamir—Tian Shan region using 10Be-derived denudation rates from modern (n = 110) and buried sediment (2.0–2.7 Ma; n = 3), and long-term exhumation rates from published apatite fission track (AFT; n = 705) and apatite (U-Th-Sm)/He (AHe; n = 211) thermochronology. We found moderate correlations between denudation rates and topographic metrics and weak correlations between denudation rates and annual rainfall, highlighting complex linkages among tectonics, climate, and surface processes that vary locally. The 10Be data show a spatial trend of decreasing modern denudation rates from west to east, suggesting that deformation and precipitation control denudation in the northern Pamir and western Tian Shan. Farther east, the denudational response of the landscape to Quaternary glaciations is more pronounced and reflected in our data. Modern 10Be denudation rates are generally higher than the long-term AFT and AHe exhumation rates across the studied area. In the Kyrgyz Tian Shan, on average, the highest 10Be denudation rates are recorded in the Terskey range, south of Lake Issyk-Kul. Here, modern denudation rates are higher than 10Be-derived paleo-denudation rates, which are comparable in magnitude with the long-term exhumation rates inferred from AFT and AHe. We propose that denudation in the region, particularly in the Terskey range, remained relatively steady during the Neogene and early Pleistocene. Denudation increased due to glacial-interglacial cycles in the Quaternary, but this occurred after the onset and intensification of the Northern Hemisphere glaciations at 2.7 Ma.

Description: Examining the links and potential feedbacks between tectonics and climate requires understanding the processes and variables controlling erosion. At the orogen scale, tectonics and climate are thought to be linked through the influence of mountain elevation on orographic precipitation and glaciation; the only documented erosional processes capable of balancing rapid rock-uplift rates are glacial erosion or coupled river incision and landsliding. Our 20 new 10Be derived catchment-averaged denudation rates from the Western Southern Alps of New Zealand generally range between 0.6 and 9 mm/yr, within the same order of magnitude as fault-throw rates, exhumation rates, and erosion rates estimated from suspended sediment yields and landslide inventories. Combining our data with previously published 10Be denudation rates, we find that the proportion of catchment area in the 1,500–2,000 m elevation window is the variable that best explains denudation rate variability and the disparity between rock-uplift rates and denudation rates. This correlation indicates that enhanced erosion likely occurs at 1,500–2,000 m above sea level, where periglacial and paraglacial processes have been proposed to be most active. We find that these temperature-controlled erosional processes, which are also elevation-dependent, can play a greater role in modulating erosion during interglacials than precipitation or glaciation. Our data suggest that temperature-controlled peri- and paraglacial erosion could be efficient enough to balance some of the fastest rock-uplift rates on Earth. Hence, temperature-controlled erosion could contribute to limiting orogen elevations and modulating the erosion rates dictated by rock-uplift, playing an essential role in linking tectonics and climate.