An official website of the United States government
Abstract River terraces are commonly used to infer climate and tectonic histories. Yet, it is increasingly recognised that other processes, such as river capture, can affect river terrace genesis and incision rates and patterns. In this study, we conduct a field‐based investigation of river terrace sequences along the Kolokithas and Varitis Rivers in central Crete, Greece, that share a confluence and preserve geomorphic evidence for the recent capture of the Kolokithas headwaters by the Varitis. We use digital topographic analysis, mapping, and optically stimulated luminescence (OSL) geochronology to quantify the river terrace and bedrock incision response to river capture. Topographic analysis indicates the Varitis captured ~30 km2of drainage area from the Kolokithas. We find differences in terrace characteristics, number of terraces, and incision rates and patterns on the adjacent valleys. The Kolokithas has four terrace levels, and the Varitis has five. All terraces are strath terraces, except for the oldest on the Kolokithas, a ~8 m thick fill terrace that starkly contrasts the time‐equivalent ~1–2 m thick strath terrace on the Varitis. Relative and absolute age control suggests three Pleistocene terraces were emplaced during cooler climate intervals, and two Holocene terraces are perhaps because of anthropogenic disturbances. The incision patterns differ on each valley, with generally more incision upstream on the Varitis relative to the Kolokithas. Incision rates on the Varitis are roughly twice as high as on the Kolokithas, but the average incision rate of both valleys combined is comparable to coastal rock uplift rates derived from marine terraces. Collectively, our results suggest that fluvial systems are sensitive to climate and tectonic processes even when affected by geomorphic disturbances, like river capture and beheading. However, care must be taken when interpreting river terraces as direct records of climate and tectonic processes, particularly when working on a single river valley.
more »
« less
This content will become publicly available on October 1, 2026
Apatite (U‐Th)/He Thermochronometry Along the Sutlej River, NW India Himalaya: Pleistocene River Capture Events Accelerated River Anticline Development
River capture events may create short‐term pulses of incision in orogenic settings, complicating the interpretation of tectonic and climatic influences on exhumation patterns. The Sutlej River in northwestern India offers a compelling case study, as recent exhumation has been linked primarily to tectonic and climatic factors, whereas the capture of the Zhada Basin has been identified at <1 Ma. This region also features active faults and a river anticline formed by rapid river incision. The integration of new (U‐Th)/He data, inverse modeling and a geomorphic analysis has revealed two recent episodes of rapid exhumation along the river anticline: (a) a 0.8–0.3 Ma pulse coinciding with the capture of the Zhada Basin, which is associated with a 2‐ to 3‐fold increase in exhumation rates in the river anticline region, and (b) a 2–1 Ma pulse linked to the potential capture of the Pare Chu River, another major tributary of the Sutlej River. Our findings suggest that these Pleistocene river capture events both led to increased exhumation downstream along the river anticline, a region susceptible to rapid exhumation via ongoing deformation and a warm weak crust. Thus, this study emphasizes how erosional perturbations, triggered by changes in drainage systems, can significantly impact topography, local exhumation patterns, and deformation dynamics during <1 Myr time periods.
more »
« less
- Award ID(s):
- 2210074
- PAR ID:
- 10644745
- Publisher / Repository:
- American Geophysical Union
- Date Published:
- Journal Name:
- Tectonics
- Volume:
- 44
- Issue:
- 10
- ISSN:
- 0278-7407
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Rates of northern Alaska Range thrust system deformation are poorly constrained. Shortening at the system's west end is focused on the Kantishna Hills anticline. Where the McKinley River cuts across the anticline, the landscape records both Late Pleistocene deformation and climatic change. New optically stimulated luminescence and cosmogenic10Be depth profile dates of three McKinley River terrace levels (~22, ~18, and ~14–9 ka) match independently determined ages of local glacial maxima, consistent with climate‐driven terrace formation. Terrace ages quantify rates of differential bedrock incision, uplift, and shortening based on fault depth inferred from microseismicity. Differential rock uplift and incision (≤1.4 m/kyr) drive significant channel width narrowing in response to ongoing folding at a shortening rate of ~1.2 m/kyr. Our results constrain northern Alaska Range thrust system deformation rates, and elucidate superimposed landscape responses to Late Pleistocene climate change and active folding with broad geomorphic implications.more » « less
-
Deep canyons along the Salmon, Snake, and Clearwater rivers in central Idaho, USA suggest long-lasting transient incision, but the timing and drivers of this incision are not well understood. The perturbation of the Yellowstone hotspot, eruption of flood basalts, and drainage of Lake Idaho all occurred within or near to this region, but the relationship among these events and incision is unclear. Here, we utilized in situ 10Be cosmogenic radionuclide concentrations for 46 samples (17 new) of fluvial sediment across the region to quantify erosion rates, calibrate stream power models, and estimate incision timing. We estimate that transient incision along the Salmon River began prior to ca. 10 Ma. However, canyon age decreases to ca. 5 Ma or earlier farther to the north. For a group of tributaries underlain by basalt, we use the age of the basalt to estimate that local transient incision began between ca. 11.5 and 5 Ma. Based on these timing constraints, the canyons along the Salmon and Clearwater rivers predate the drainage of Lake Idaho. We argue that canyon incision was triggered by events related to the Yellowstone hotspot (e.g., basalt lava damming, subsidence of the Columbia Basin, reactivation of faults, and/or lower crustal flow). Furthermore, our models suggest basalt may be more erodible than the other rock types we study. We show that lithology has a significant influence on fluvial erosion and assumptions regarding river incision model parameters significantly influence results. Finally, this study highlights how geodynamic processes can exert a significant influence on landscape evolution.more » « less
-
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.more » « less
-
This study assesses the impact of fold-thrust belt driven deformation on the topographic evolution, bedrock exhumation and basin formation in the southeastern Peruvian Andes. We do this through a flexural and thermokinematically modelled balanced cross-section. In addition, published thermochronology samples from low-elevation (river canyons) and high-elevation (interfluves) and Cenozoic sedimentary basin datasets along the balanced cross-section were used to evaluate the age, location, and geometry of fault-driven uplift, as well as potential relationships to the timing of ∼2 km of canyon incision. The integrated structural, thermochronologic, and basin data were used to test the sensitivity of model results to various shortening rates and durations, a range of thermophysical parameters, and different magnitudes and timing of canyon incision. Results indicate that young apatite (U-Th)/He (AHe) canyon samples from ∼2 km in elevation or lower are consistent with river incision occurring between ∼8–2 Ma and are independent of the timing of ramp-driven uplift and accompanying erosion. In contrast, replicating the young AHe canyon samples located at >2.7 km elevation requires ongoing ramp-driven uplift. Replicating older interfluve cooling ages concurrent with young canyon ages necessitates slow shortening rates (0.25–0.6 mm/y) from ∼10 Ma to Present, potentially reflecting a decrease in upper plate compression during slab steepening. The best-fit model that reproduces basin ages and depositional contacts requires a background shortening rate of 3–4 mm/y with a marked decrease in rates to ≤0.5 mm/y at ∼10 Ma. Canyon incision occurred during this period of slow shortening, potentially enhanced by Pliocene climate change.more » « less
