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1. Tectonic controls on Quaternary landscape evolution in the Ventura basin, southern California, USA, quantified using cosmogenic isotopes and topographic analyses

   https://doi.org/10.1130/B36076.1  

   Hughes, A.; Rood, D.H.; DeVecchio, D.E.; Whittaker, A.C.; Bell, R.E.; Wilcken, K.M.; Corbett, L.B.; Bierman, P.R.; Swanson, B.J.; Rockwell, T.K. (January 2022, GSA Bulletin)

   Abstract The quantification of rates for the competing forces of tectonic uplift and erosion has important implications for understanding topographic evolution. Here, we quantify the complex interplay between tectonic uplift, topographic development, and erosion recorded in the hanging walls of several active reverse faults in the Ventura basin, southern California, USA. We use cosmogenic 26Al/10Be isochron burial dating and 10Be surface exposure dating to construct a basin-wide geochronology, which includes burial dating of the Saugus Formation: an important, but poorly dated, regional Quaternary strain marker. Our ages for the top of the exposed Saugus Formation range from 0.36 +0.18/-0.22 Ma to 1.06 +0.23/-0.26 Ma, and our burial ages near the base of shallow marine deposits, which underlie the Saugus Formation, increase eastward from 0.60 +0.05/-0.06 Ma to 3.30 +0.30/-0.41 Ma. Our geochronology is used to calculate rapid long-term reverse fault slip rates of 8.6–12.6 mm yr–1 since ca. 1.0 Ma for the San Cayetano fault and 1.3–3.0 mm yr–1 since ca. 1.0 Ma for the Oak Ridge fault, which are both broadly consistent with contemporary reverse slip rates derived from mechanical models driven by global positioning system (GPS) data. We also calculate terrestrial cosmogenic nuclide (TCN)-derived, catchment-averaged erosion rates that range from 0.05–1.14 mm yr–1 and discuss the applicability of TCN-derived, catchment-averaged erosion rates in rapidly uplifting, landslide-prone landscapes. We compare patterns in erosion rates and tectonic rates to fluvial response times and geomorphic landscape parameters to show that in young, rapidly uplifting mountain belts, catchments may attain a quasi-steady-state on timescales of <105 years even if catchment-averaged erosion rates are still adjusting to tectonic forcing. 

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2. Exhumation and incision of the eastern Central Andes, southern Peru: Low-temperature thermochronology observations

   https://doi.org/10.1016/j.epsl.2023.118299  

   Falkowski, Sarah; Ehlers, Todd A; McQuarrie, Nadine; Glover, Chloë O; Perez, Nicholas D; Buford_Parks, Victoria M (October 2023, Earth and Planetary Science Letters)

   Quantifying the impacts of past changes in tectonics or climate on mountain topography has proven challenging. The incision of the eastern Central Andean Plateau has been interpreted as both a result of deformation-related uplift and erosion and climate-driven erosion. Here, we contribute >100 new apatite and zircon (U-Th)/He and fission-track dates from 51 new and eight previous bedrock samples. These samples were combined with previous thermochronometer data from three ∼190-km-long and ∼200-km-apart across-strike transects along the eastern margin of the Andean Plateau in southern Peru. We discuss age-distance, age-elevation, and inverse thermal history model results along these transects to constrain the timing and extent of recent canyon incision compared to the region’s long-term (∼40 Myrs) exhumation history. Results indicate that, along the plateau flank, long-term, deformation-related exhumation is superimposed by a regional, synchronous canyon incision-related signal since ∼4–3 Ma. This incision is traceable from at least the Abancay Deflection in southern Peru to southern Bolivia along the eastern Central Andes. Based on the regional and synchronous character of canyon incision across areas with different deformation histories and exhumation magnitude, we suggest that paleoclimate change was a significant contributor to incision. However, structural processes resulting in surface uplift, erosion, and exhumation continued post-mid Miocene and contributed to the observed exhumation magnitude. 

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3. Integrated uplift, subsidence, erosion and deposition in a tightly coupled source‐to‐sink system, Pagliara basin, northeastern Sicily, Italy

   https://doi.org/10.1111/bre.12845  

   Pavano, F.; Pazzaglia, F. J.; Rittenour, T. M.; Catalano, S.; Corbett, L. B.; Bierman, P. (January 2024, Basin Research)

   Abstract How tectonic forcing, expressed as base level change, is encoded in the stratigraphic and geomorphic records of coupled source‐to‐sink systems remains uncertain. Using sedimentological, geochronological and geomorphic approaches, we describe the relationship between transient topographic change and sediment deposition for a low‐storage system forced by rapid rock uplift. We present five new luminescence ages and two terrestrial cosmogenic nuclide paleo‐erosion rates for the late Pleistocene Pagliara fan‐delta complex and we model corresponding base level fall history and erosion of the source catchment located on the Ionian flank of the Peloritani Mountains (NE‐Sicily, Italy). The Pagliara delta complex is part of the broader Messina Gravel‐and‐Sands lithostratigraphic unit that outcrops along the Peloritani coastal belt as extensional basins have been recently inverted by both normal faults and regional uplift at the Messina Straits. The deltas exposed at the mouth of the Pagliara River have constructional tops at ca. 300 m a.s.l. and onlap steeply east‐dipping bedrock at the coast to thickness between ca. 100 and 200 m. Five infrared‐stimulated luminescence (IRSL) ages collected from the delta range in age from ca. 327 to 208 ka and indicate a vertical long‐term sediment accumulation rate as rapid as ca. 2.2 cm/yr during MIS 7. Two cosmogenic¹⁰Be concentrations measured in samples of delta sediment indicate paleo‐erosion rates during MIS 8–7 near or slightly higher than the modern rates of ca. 1 mm/yr. Linear inversion of Pagliara fluvial topography indicates an unsteady base level fall history in phase with eustasy that is superimposed on a longer, tectonically driven trend that doubled in rate from ca. 0.95 to 1.8 mm/yr in the past 150 ky. The combination of footwall uplift rate and eustasy determines the accommodation space history to trap the fan‐deltas at the Peloritani coast in hanging wall basins, which are now inverted, uplifted and exposed hundreds of metres above the sea level. 

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4. Impact of fault damage on eastern Tibet topography

   https://doi.org/10.1130/G48179.1  

   Kirkpatrick, Heather M.; Moon, Seulgi; Yin, An; Harrison, T. Mark (August 2020, Geology)

   null (Ed.)

   Tectonic deformation can influence spatiotemporal patterns of erosion by changing both base level and the mechanical state of bedrock. Although base-level change and the resulting erosion are well understood, the impact of tectonic damage on bedrock erodibility has rarely been quantified. Eastern Tibet, a tectonically active region with diverse lithologies and multiple active fault zones, provides a suitable field site to understand how tectonic deformation controls erosion and topography. In this study, we quantified erosion coefficients using the relationship between millennial erosion rates and the corresponding channel steepness. Our work shows a twofold increase in erosion coefficients between basins within 15 km of major faults compared to those beyond 15 km, suggesting that tectonic deformation through seismic shaking and rock damage significantly affects eastern Tibet erosion and topography. This work demonstrates a field-based, quantitative relationship between rock erodibility and fault damage, which has important implications for improving landscape evolution models. 

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5. The Importance of Hillslope Scale in Responses of Chemical Erosion Rate to Changes in Tectonics and Climate

   https://doi.org/10.1029/2020JF005562  

   Ferrier, K. L.; Perron, J. T. (September 2020, Journal of Geophysical Research: Earth Surface)

   Abstract Chemical erosion is of wide interest due to its influence on topography, nutrient supply to streams and soils, sediment composition, and Earth's climate. While controls on chemical erosion rate have been studied extensively in steady‐state models, few studies have explored the controls on chemical erosion rate during transient responses to external perturbations. Here we develop a numerical model for the coevolution of soil‐mantled topography, soil thickness, and soil mineralogy, and we use it to simulate responses to step changes in rates of rock uplift, soil production, soil transport, and mineral dissolution. These simulations suggest that tectonic and climatic perturbations can generate responses in soil chemical erosion rate that differ in speed, magnitude, and spatial pattern and that climatic and tectonic perturbations may impart distinct signatures on hillslope mass fluxes, soil chemistry, and sediment composition. The response time of chemical erosion rate is dominantly controlled by hillslope length and is secondarily modulated by rates of rock uplift, soil production, transport, and mineral dissolution. This strong dependence on drainage density implies that a landscape's chemical erosion response should depend on the relative efficiencies of river incision and soil transport and thus may be mediated by climatic and biological factors. The simulations further suggest that the timescale of the hillslope response may be long relative to that of river channel profiles, implying that chemical erosion response times may be limited more by the sluggishness of the hillslopes than by the rate of signal propagation through river channel profiles. 

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