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Evolution of topography, Be10 production rate, and erosion rate through time after response to basal accretion by duplex formation at depth, simulated using the TopoToolbox Landscape Evolution Model. (a and b) Transient topographies after initial (a) and further response (b) to basal accretion, simulated by moving a 10‐km‐wide high rock‐uplift zone across the model domain. The 10‐km‐wide hatched region experiences an uplift rate of 5 mm yr−1, whereas the model domain outside the hatched region experiences a constant rock uplift rate of 1 mm yr−1. (c) Evolution of the simulated mountain topography and the consequent variation of cosmogenic Be10 production rate through time. Blue arrows indicate times when both topographic snapshots (a and b) are created. Red arrows mark the onset of high rock‐uplift zone migration. (d) Simulated actual and Be10‐derived erosion rates through time (for details, see Appendix A).
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The evolution of Earth's climate over geological timescales is linked to surface erosion via weathering of silicate minerals and burial of organic carbon. However, methodological difficulties in reconstructing erosion rates through time and feedbacks among tectonics, climate, and erosion spurred an ongoing debate on mountain erosion sensitivity to...
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... Also, sediment fluxes during the Neogene are compatible with rapid tectonic uplift in Myanmar. In addition, tectonic erosion and crustal removal show similar patterns in the evolution of Japanese forearc sediment provenance (Pastor-Galán et al. 2021) as well as with tectonic accretion processes (Mandal et al. 2021). ...
Denudation involves weathering mountains and soil formation over long periods and is classified as soil degradation. This study focuses on the relationship between uplift and denudation using the hypsometric index (HI) and river profile steepness as key points to describe erosional processes and their relationship with environmental land degradation in the Zagros Fold and Thrust Belt (ZFTB). The interplay between tectonics, climate, and geomorphological features has been investigated to shed light on the erosional processes in the ZFTB. There is uniformity between regions of higher precipitation, steep slopes, higher river steepness, and higher HI, particularly, in areas to the northeast of the Kirkuk Embayment (KE) and areas of Bakhtyari Culmination (BCu). Higher-strength lithologies show consistency with the areas of higher HI, steepness, and higher precipitation, implying that the erodibility of exposed lithology does not control higher geomorphic indices values. The results showed a coupling between climate (e.g., orographic rain) and tectonic uplift controlling higher erosion areas (land degradation), where we found steep slopes, high HI, and steepness values.
... However, this proxy is not applicable for reconstructing paleo-weathering rates using continuously deposited (paleo-)lacustrine or marine sediments. Although in-situ produced cosmogenic nuclides (Lenard et al., 2020) have been utilized to reconstruct paleo-denudation rates, the temporal resolution is constrained by the intermittent deposition of quartz-bearing rocks in sediment cores for in-situ cosmogenic dating (Mandal et al., 2021;Zhang et al., 2023). Similarly, the reconstruction of Earth's surface exhumation rate using thermochronology (Herman et al., 2013) also faces challenges, primarily the lack of suitable bedrocks with a continuous cooling history. ...
Quantifying Earth’s surface denudation rates is crucial for estimating sediment flux and its role in regulating global climate change. The inability of in-situ cosmogenic 10Bein to quantify denudation rates in quartz free environment has prompted the need for a new proxy–the ratio of meteoric 10Bemet to mineral-weathered 9Be in reactive phase (precipitated in or adsorbed onto secondary minerals). This study utilized 10Bein 26Alin, 10Bemet/9Be, and major element analyses of reactive and mineral phases of bedload sediments to infer basin-wide denudation rates and sediment recycling (reworking of deeply buried sediments) in the Three River Source Region (TRSR) of the central Tibetan Plateau. Results from 10Bein-26Alin analysis of bedload sediments and bedrock samples (quartz grain, 250–500 μm) suggest that the sediments underwent burial events since at least 0.54 ± 0.16 million years ago. Combining paleoclimate records in the central Tibetan Plateau, we interpret the "Great Burial" as most likely the result of climate-controlled deglaciation and denudation at the termination of Naynayxungla glaciation during the MIS 13–15 period. This event marks the first widespread deglaciation on the Tibetan Plateau. The 10Bein-26Alin derived paleo denudation rates range from 4.2 (-0.8,+0.9) to 151 (-32,+37) mm/kyr, consistent with previous 10Bein derived modern denudation rates of 10–117 mm/kyr in TRSR. These rates show a moderate positive correlation with regional topography, particularly channel steepness, indicating a decrease in both relief and denudation rates from lower to upper streams. This spatial discrepancy is likely due to enhanced river headward incision and active neotectonic activities in the southeast. Denudation rates derived from the 10Bemet/9Be proxy range from 13 to 248 mm/kyr, alongside a chemical weathering intensity ranging from 43% to 67%. These denudation rates are strongly correlated with, but about 1.5 times higher than, the 10Bein 26Alin derived paleo denudation rates from the same watershed. This suggests that the 10Bemet/9Be extracted from fine grains (< 64 μm) may reflect a different sediment recycling pattern compared to 10Bein 26Alin in quartz sediments. Alternatively, the 10Bemet/9Be ratio could indicate a mixture of carbonate rock with a high denudation rate and silicate rock with a lower denudation rate, whereas 10Bein 26Alin reflects a single silicate denudation signal.
... 4 of 26 and present-day erosion rates in the hinterland source regions (Mandal et al., 2021;Scherler et al., 2014). Fourth, geophysical data constrain the décollement geometry, which is the dominant cause for spatial variations in uplift rate across the range (Powers et al., 1998). ...
... The Asan and Suswa-Song Rivers set the base level for north-draining rivers, whereas the Gangetic Plain sets the base level for south-draining rivers (Figure 4a). The drainage divide reaches ∼800-900 m Mandal et al. (2021) and red circle shows location of sample analyzed for 10 Be by Lupker et al. (2012). B-B' = location of the balanced structural cross section shown in panel (c). ...
... The cumulative concentration of in situ-produced CRN in sediment recycled from an uplifted foreland succession (N) consists of concentrations acquired during paleoerosion in the hinterland (N E ), transport to the foreland (N T ), deposition and burial in the foreland (N B ), adjusted for radioactive decay losses, and augmented by renewed accumulation resulting from erosion of the uplifting foreland succession (N X ) ( Figure 2; steps 1-5) (e.g., Charreau et al., 2011;Mandal et al., 2021). Before reaching the foreland, sediments may be stored in intermontane valleys at the rapidly eroding front of the Himalaya for a considerable period. ...
The Himalayan orogen exports millions of tons of sediment annually to the Indo‐Gangetic foreland basin, derived from both hinterland and foreland fold‐thrust belts (FTB). Although erosion rates in the hinterland are well‐constrained, erosion rates in the foreland FTB and, by extension, the sediment flux have remained poorly constrained. Here, we quantified erosion rates and sediment flux from the Mohand Range in the northwestern Himalaya by modeling and measuring the cosmogenic radionuclide (CRN) ¹⁰Be and ²⁶Al concentrations in modern fluvial sediments. Our model uses local geological and geophysical constraints and accounts for CRN inheritance and sediment recycling, which enables us to determine the relative contributions of the hinterland and foreland FTB sources to the CRN budget of the proximal foreland deposits. Our model predictions closely match measured concentrations for a crustal shortening rate across the Mohand Range of 8.0 ± 0.5 mm yr⁻¹ (i.e., approximately 50% of the total shortening across the Himalaya at this longitude) since 0.75−0.06+0.02 $0.7{5}_{-0.06}^{+0.02}$ Ma. This shortening implies a spatial gradient in erosion rates ranging from 0.42 ± 0.03 to 4.92 ± 0.34 mm yr⁻¹, controlled by the geometry of the underlying structure. This erosion pattern corresponds to an annual sediment recycling of ∼2.0 megatons from the Mohand Range to the downstream Yamuna foreland. Converted to sediment fluxes per unit width along the Himalaya, the foreland FTB accounts for ∼21% ± 5% of the total flux entering the foreland. Because these sediments have lower ¹⁰Be concentrations than hinterland‐derived sediment, they would lead to ∼14% overestimation of ¹⁰Be‐derived erosion rates, based on Yamuna sediments in the proximal foreland.
... At the Indus headwaters in the arid western Tibetan-Plateau margin, valley fill deposits are estimated to have residence times up to ∼0.5 Myr (Clift and Giosan, 2014;Munack et al., 2016). However, lag time and burial duration in dynamic regions or orogenic settings such as the Himalaya and the proximal part of the foreland basin, have always been argued to be negligible (e.g., Lupker et al., 2012;Rahaman et al., 2017;Lenard et al., 2020;Mandal et al., 2021). There are limited data supporting longer residence time of sediments in the Ganges-Brahmaputra floodplain (Goodbred, 2003), but quantification of residence time remains elusive for large parts of the catchment (Lupker et al., 2012;Wittmann et al., 2020). ...
Sediment burial can lead to significant lag times during sediment transport and is an important component of the sediment cycle. The Indo-Gangetic Plain (IGP) is a large sediment conveyer belt and understanding sediment lag times on various time scales is important for short- and long-term sediment transport and denudation-rate estimations. In this study, we have quantified the transport lag time in terms of burial duration with 14 different alluvial drill cores from 4 major Himalayan river basins, including the Ghaggar, Paleo-Yamuna, Ganges, and Kosi rivers. We rely on 56 samples using the paired cosmogenic radionuclides, 26Al and 10Be. The coring locations of paleo-Yamuna and Kosi, along with one of the Ghaggar cores are within ∼100 km from the mountain front, while the Ganges cores are ∼350 km away. The coring locations cover an E-W distance of ∼1200 km on the IGP and the depositional ages range from ∼120 kyr BP to the present day based on previous age estimations. Out of 56 samples, 39 samples show a burial signal ranging from 0.61±0.33 Myr to 3.75±1.9 Myr, with outlier values as large as ∼6 Myr.
We show that the Kosi samples due to their proximity to the mountain front show no burial or a lower mean burial duration of ∼1.01 Myr, compared to the samples from the coring locations well within the IGP, such as the Ghaggar (∼2.48 Myr) and the Ganges (∼2.36 Myr). However, despite its proximity to the mountain front, the paleo-Yamuna samples have a mean burial duration of ∼2.20 Myr. Along with the floodplains and megafan surface of the IGP, we identify two potential major sediment-lag sources in the Himalayan catchment: The high and low elevation broad valleys and the Siwaliks. Increased storage spaces in the valleys north of the main Himalayan crest, including drainage-captured catchments are likely to provide long burial durations such as in the case of the Kosi and Ghaggar basins. The upper and middle Siwaliks with burial duration in the range of up to ∼6 Myr constitute a second source. We attribute the no-burial signals of 7 samples of the Kosi basin to rapid sediment generation and transportation, driven by dynamic hillslope erosion and fluvial dynamics.
Importantly, our data suggest that even samples close to the mountain front exhibit million years of burial duration. These findings suggest that denudation rates derived from modern river sands or in paleo settings will need to account for burial duration and associated processes.
... tion of the kinematics of tectonic transport along the MHT similarly depends on the timescale considered. Orogenic wedges, like the Himalaya, grow primarily by frontal and basal accretion of crustal rocks, each of which lead to distinct rock-uplift patterns (Gutscher et al., 1996;Naylor & Sinclair, 2007;Mercier et al., 2017;Dal Zilio et al., 2020b;S. K. Mandal et al., 2021). Instantaneous to short-term (10 3 -10 4 y) deformation can be modelled satisfactorily by passive motion over a stable ramp-flat-ramp system (Cattin & Avouac, 2000;Lavé & Avouac, 2001;Grandin et al., 2012;Scherler et al., 2014;Dal Zilio et al., 2021), i.e., by frontal accretion. In contrast, balanced cross-sections imply a complex histo ...
... Both theoretical (Naylor & Sinclair, 2007;Mercier et al., 2017) and recent observational (S. K. Mandal et al., 2021) studies suggest that the Himalayan wedge may be experiencing cycles of frontal versus basal accretion on timespans of a few million years. Each cycle would then lead to migration of the active ramp in the MHT. ...
... Lesser Himalayan thrust nappes referred to as the Lesser Himalayan Duplex. These reconstructions also document that the ramp-flat structures are not a permanent structural feature over the time of its evolution, but rather migrate throughout Neogene times (Colleps et al., 2019), linked to the accretion cycles described above (Mercier et al., 2017;S. K. Mandal et al., 2021). ...
... To construct the 3D development of a folding landscape with both uplift and erosion, we carried out numerical simulations using the TopoToolbox Landscape Evolution Model (TTLEM) (Campforts et al., 2017). TTLEM is an open-access MATLAB-based landscape evolution model that has also been used to model drainage divide migration in response to tectonic forcing (He et al., 2021a(He et al., , 2021b, and erosion in the Himalayas (e.g., Mandal et al., 2021). The soil or regolith density moved by surfaces processes downslope is different to that of the bedrock. ...
Fold-and-thrust belts (FTBs) develop widely in and around active orogenic belts on Earth. With the accumulation of structural shortening, thrust-related folds can grow by increasing their amplitudes and lengths, providing insights into the structural evolution of FTBs. Investigations of fold growth patterns and landscape responses through time and space have important implications for hydrocarbon exploration and geo-hazard assessment. Evidence for lateral fold propagation (i.e., increase in length) usually comes from geochronological constraints based on differences in onset timings along strike. However, these traditional methods are time consuming and economically costly. Alternatively, previous studies have proposed the use of geomorphic features to investigate the lateral fold propagation, including spatial variations in the patterns and densities of river channels, the configuration of the topographic profile along the fold crest, and the occurrence of wind gaps. However, such analyses are based on morphological features of present-day landscapes, which still need process-based validations. Here, we conduct a series of landscape evolution models to reproduce fold growth and their associated geomorphic adjustments. Our results show that deflected rivers and inflected fold-crest elevation profile with decreasing gradient are reliable evidence of lateral fold propagation. The location of propagation is in accordance with the distribution of crest-profile slope breaks and the position where river deflection began. Then, we apply these findings to two natural examples located at the deformation fronts of the Tian Shan (NW China). Results suggest that 1) the Kashi anticline has experienced lateral propagation both westwards and eastwards; and 2) that the Yaken anticline has experienced accelerated tectonic uplift as well as eastwards propagation. These findings are supported by the constraints from geochronological dating and quantitative structural analysis. Future work that integrates folding mechanisms may provide novel insights into landscape response to complex deformation in active FTBs.
... In situ produced cosmogenic 10 Be and 26 Al are now routinely applied in the Earth sciences [1] and new applications demand higher accuracy and precision at increasingly lower nuclide abundances (e.g., [2][3][4][5][6]). Sample preparation procedures employed to isolate Be and Al for accelerator mass spectrometry (AMS) of 10 Be and 26 Al have a direct effect on sample throughput, background levels, and sample beam currents achieved during AMS measurement (e.g., [7][8][9][10][11]). ...
... Further complications arise in deciphering the primary driver of erosion in orogenic systems due to the common spatial coincidence between precipitation, topographic relief maxima, and deformational foci as a consequence of orographic effects 7 . excursions in climate [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] . Unfortunately, these studies are rarely straightforward, and commonly rely on less-than-ideal field exposures, temporal controls, and source-area and cosmogenic radionuclide systematic constraints. ...
It has long been hypothesized that climate can modify both the pattern and magnitude of erosion in mountainous landscapes, thereby controlling morphology, rates of deformation, and potentially modulating global carbon and nutrient cycles through weathering feedbacks. Although conceptually appealing, geologic evidence for a direct climatic control on erosion has remained ambiguous owing to a lack of high-resolution, long-term terrestrial records and suitable field sites. Here we provide direct terrestrial field evidence for long-term synchrony between erosion rates and Milankovitch-driven, 400-kyr eccentricity cycles using a Plio-Pleistocene cosmogenic radionuclide paleo-erosion rate record from the southern Central Andes. The observed climate-erosion coupling across multiple orbital cycles, when combined with results from the intermediate complexity climate model CLIMBER-2, are consistent with the hypothesis that relatively modest fluctuations in precipitation can cause synchronous and nonlinear responses in erosion rates as landscapes adjust to ever-evolving hydrologic boundary conditions imposed by oscillating climate regimes.
... Tectonics and climate are the two main forcing agents that control erosion and sediment delivery from mountains to basins (e.g., Strecker et al., 2007;Clift, 2017;Adams et al., 2020). Although these two controlling factors could be coupled (e.g., Whipple, 2009;Godard et al., 2014), most studies link million-year timescale sediment fluxes to tectonic perturbations (e.g., Vannay et al., 2004;Mandal et al., 2021), while millennial-scale variations in sediment transfer processes in the Himalaya are often attributed to climatic perturbations (e.g., Owen et al., 2002;Gibling et al., 2005;Dey et al., 2016). Variations in climatic strength depend on 1-10 ka monsoon cycles and 50-100 ka glacial-interglacial cycles that influence river discharge and sediment flux (e.g., Goodbred and Kuehl, 2000;Bookhagen et al., 2005aClift et al., 2008;Bookhagen and Strecker, 2012;Scherler et al., 2015;Tofelde et al., 2017;Dey et al., 2021). ...
Sediment transfer from the interiors of the Himalaya is complex because the archives are influenced by both glacial and mon-soonal cycles. To deconvolve the coupling of glacial and monsoonal effects on sediment transfer processes, we investigate the Late Pleistocene-Holocene sediment archive in the Upper Chenab valley. Optically stimulated luminescence (OSL) ages from the archive indicate major aggradation during ca. 20-10 ka. Isotopic fingerprinting using Sr-Nd isotopes in silt fractions together with clast counts in boulder-pebble fractions indicate a decreasing Higher Himalayan sediment flux in the archive with time. Decreasing clast size, increasing clast roundness, increasing matrix to clast ratio, and dominance of the Higher Himalayan sourcing unequivocally suggest strong glacial influence during the initial stages of the archive formation. This evidence also agrees with the existing retreat ages of glaciers in the Upper Chenab valley. Results of our study also show that the upper parts of the archive contain significant fluvial sediment contribution from the Lesser Himalaya, which suggests an active role of the stronger Indian Summer Monsoon (ISM) in the region during the Early Holocene. The apparent decrease in sediment supply from the Higher Himalayan sources could have been due to longer source-to-sink transport in the Early Holocene and/or increased hillslope flux from Lesser Himalayan sources.
... The physical and thermal evolution of mountain belts is governed by the interplay between tectonic deformation, the production and transfer of heat, crustal metamorphism, and surface denudation. The extent to which surficial processes (e.g., climate and erosion) can modulate deep crustal metamorphic and tectonic processes is poorly known (1)(2)(3). The places on Earth where surface denudation is most likely to exert control on deeper crustal processes are the syntaxial massifs of the Himalaya-the Namche Barwa massif (NBM) in the east and the Nanga Parbat massif (NPM) in the west (Fig. 1). ...
We combine monazite petrochronology with thermal modeling to evaluate the relative roles of crustal melting, surface denudation, and tectonics in facilitating ultrafast exhumation of the Nanga Parbat Massif in the western Himalayan syntaxis. Our results reveal diachronous melting histories between samples and a pulse of ultrafast exhumation (9 to 13 mm/year) that began ~1 Ma and was preceded by several million years of slower, but still rapid, exhumation (2 to 5 mm/year). Recent studies show that an exhumation pulse of similar timing and magnitude occurred in the eastern Himalayan syntaxis. A synchronous exhumation pulse in both Himalayan syntaxes suggests that neither erosion by rivers and/or glaciers nor a pulse of crustal melting was a primary trigger for accelerated exhumation. Rather, our results, combined with those of recent studies in the eastern syntaxis, imply that larger-scale tectonic processes impose the dominant control on the current tempo of rapid exhumation in the Himalayan syntaxes.
