Orals: Mon, 28 Apr | Room G2
The influence of Quaternary climate (i.e., glacial-interglacial cycles) on mountain topography remains a topic of debate, largely due to the challenges associated with measuring surface processes over the recent geological past. A compelling location to investigate mountain erosion in response to Quaternary climate change is found in the Tateyama Mountains, part of the Hida mountain range in the northern Japanese Alps, due to its distinct geomorphological features. The Japanese Alps uplifted within the last 1–3 million years and have undergone multiple glaciations during the late Quaternary. In this study, we employ novel ultra-low temperature thermochronometers based on the luminescence and electron spin resonance (ESR) from feldspar and quartz minerals, respectively, in combination with numerical (inverse) modelling to derive rock cooling and exhumation rate histories on timescales of 10⁴–10⁶ years within the Tateyama region.
The different infra-red stimulated luminescence signals measured have already reached their upper dating limit, indicating maximum exhumation rates of approximately 1-1.5 mm/yr. In contrast, ESR signals from Al and Ti centres provided ESR ages ranging from ca. 0.3 to 1.1 million years, suggesting that surface processes were active during the Pleistocene. A negative age-elevation relationship reveals a reduction in local relief at the scale of the cirque basin over the past million years. However, a positive age-elevation trend observed in samples from near the mountain summit deviates from this pattern. Inverse modelling shows rock cooling rates ranging from 20 to 70 °C/Myr, with slightly faster cooling in cirque-floor samples. Both 1D and 3D thermal kinematic modelling reveal erosion rates of 0.5–1 mm/yr in the cirque basin, which are higher than those observed from periglacial and slope processes in the same area. Our data suggest that Quaternary climate change, coupled with distinct surface processes, has significantly altered the slopes of the Tateyama mountains, leading to a localized decrease in relief within individual cirque basins during the second half of the Quaternary (Bartz et al., 2024).
Bartz, M., King, G.E., Bernard, M., Herman, F., Wen, X., Sueoka, S., Tsukamoto, S., Braun, J., Tagami, T., 2024. The impact of climate on relief in the northern Japanese Alps within the past 1 Myr – The case of the Tateyama mountains. Earth and Planetary Science Letters 644, 118830.
How to cite: Kranz-Bartz, M., King, G. E., Bernard, M., Herman, F., Wen, X., Sueoka, S., Tsukamoto, S., Braun, J., and Tagami, T.: Unveiling the impact of Quaternary climate on mountain erosion: new insights from the Japanese Alps using novel trapped charge thermochronometry, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14764, https://doi.org/10.5194/egusphere-egu25-14764, 2025.
Constraining the topographic impact of Quaternary glaciation in the European Alps is important to better assess the control of climate on mountain erosion rates over 104-106 yr timescales. Infra-red stimulated luminescence (IRSL) in feldspar is a dating technique that allows quantification of trapped electrons and the potential reconstruction of rock thermal histories over a timescale of 104-105 years. During the cooling of rocks, ionizing radiation leads to the temporary trapping of electrons in crystal defects. The rate of electron release from these traps depends on the traps’ thermal activation energy as well as their spatial density (controlling their purely athermal loss via quantum mechanical tunnelling). However, interpreting luminescence signals requires that the electron trapping and detrapping models correctly replicate well-constrained thermal histories, both in the laboratory and natural environments. Existing models, such as single saturating exponential (SSE) and general-order kinetics (GOK) for trapping, and band-tail states (BTS) for detrapping, have been previously tested and validated for some benchmark areas. However, these models appear inadequate for our new experimental K-feldspar IRSL dataset from the Mont-Blanc massif (European Alps), e.g. by misfitting laboratory trapping-detrapping behaviour (SSE + BTS) or failing to reproduce dose-dependent isothermal decay curves (GOK). To address these limitations, we introduce a new trapping-detrapping model consisting of a log-normal distribution of trap characteristic doses (D0 values) and of their thermal lifetimes. This model is internally consistent, mathematically in line with former approaches, verifiable on existing IRSL results from the KTB-borehole, and demonstrates excellent predictive capabilities with respect to our Mont-Blanc dataset. Using this model, we investigated the last 100-kyr cooling history of nine samples from the Mont-Blanc tunnel. Our results suggest that the subsurface cooled by approximately 10–30 °C over the past 20 kyr, implying a potential link to the last deglaciation relating to (1) valley incision and/or (2) cold water infiltration provided by melting glaciers.
How to cite: Bernard, M., Lambert, R., King, G., Guralnik, B., Herman, F., Valla, P., and Schmidt, C.: Infra-red stimulated luminescence on K-feldspar: evaluation of a new trapping-detrapping model and perspectives on the late-stage cooling history of the Mont-Blanc massif, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17069, https://doi.org/10.5194/egusphere-egu25-17069, 2025.
The tectonic evolution of orogenic systems, such as the Himalayas, has been extensively studied using thermochronometers sensitive to temperatures above 120 °C. Landscape modelling and the inversion of these data provide estimates of deformation rates over timescales of millions of years and spatial scales of tens to hundreds of kilometres. For the Himalayas, these data generally support a Quaternary tectonic scenario dominated by duplexing, where the collision between the Indian and Eurasian plates is accommodated along the active Main Himalayan Thrust (MHT), expressed at the surface as the Main Frontal Thrust (MFT) at the southern front of the Himalayan range. With this model, the observed exhumation of the High Himalayas is driven by underplating beneath the topographic transition, which creates duplex structures and overthrusting. However, several studies challenge this model, highlighting the scarcity of data constraining deformation rates in the Lesser Himalayas, and the absence of thermochronometric data for recent (< 2 Ma) movements.
Trapped-charge thermochronometry, sensitive to ultra-low temperatures below 100 °C, offers new constraints on the final stages of exhumation of the Himalayas (last few kilometres), constraining rates of deformation on sub-Quaternary timescales. Analysis of trapped charge thermochronometry data (luminescence and electron spin resonance) indicate that the MFT has accommodated at least 62 % of the convergence since 200 ka, while also revealing localized fault activity within the Sub-Himalayan fold-and-thrust belt, suggesting strain partitioning. High exhumation rates in the Main Central Thrust (MCT) area, along with differing apparent ages and exhumation rates on each side of the MCT fault system during the late Quaternary point to potential out-of-sequence fault activity, challenging the in-sequence/duplexing model proposed by higher temperature thermochronometers. However, these findings alone cannot definitively favour one tectonic model over another, and further investigation through fault kinematics and landscape modeling is required.
To address this, we employ a 3-D thermo-kinematic landscape evolution model (Pecube), and perform a formal nonlinear inversion using the Neighborhood Algorithm. This approach couples a landscape evolution model with 2-D thermo-kinematic models to simulate regional landscape evolution of the Nepal Himalayas, assessing how different kinematics can explain the morphology of the region. By combining fault geometries, vertical and horizontal displacement trajectories, and surface processes simulations, we will differentiate between the in-sequence/duplexing and out-of-sequence deformation modes for the Quaternary period. This integrated modeling framework will help identify the relative roles of tectonics, climate, and geology in shaping the exhumation patterns in the foreland and hinterland, as well as across different valleys in Nepal. Ultimately, the thermo-kinematic model will also provide insights into the seismic behaviour of the Nepalese mountain belt during the Quaternary.
How to cite: Bouscary, C., Tsukamoto, S., and Braun, J.: Modelling central Nepal Himalayan tectonic from different temperature thermochronometers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19499, https://doi.org/10.5194/egusphere-egu25-19499, 2025.
Late Mesozoic subduction and retreat of the Paleo-Pacific Plate constructed a vast back-arc region with numerous extensional basins and extensive magmatic activities that destroyed the east South China Craton.Widespread extensional structures are always controlled by detachment faults, which provide direct constraint ofthe precise tectonic process of craton destruction. At the westernmost end of this back-arc region, we identify a unique, two-detachment extensional system, the Yuechengling dome with the Ziyuan Detachment in the west and the Tianhu Fault at the middle. Low-temperature geochronology shows that during the extension at 100-85 Ma, the Ziyuan Detachmentevolved progressively with a north-to-south migration pattern. At the same time, the Tianhu Fault was also reactivated. Its northern segment experienced rapid cooling from 85-70 Ma, and the southern segment was in a rapid cooling stage from 70-45 Ma. This trend reflects heterogeneous evolution and exhumation related to the subduction retreat of the Paleo-Pacific. The uplift and denudation process from 10-0 Ma obtained from the thermal history inversion of the Tianhu Fault and the Ziyuan Detachment may be related to crustal thermal subsidence. According to the Airy - Heiskanen Model, combined with the regional low-temperature geochronology data, we calculated that the denudation thickness in the Yuechengling area reached approximately 2000 m. Combining with the current altitude, it is speculated that the altitude in the Yuechengling area reached approximately 2900 ± 300 m during the Late Mesozoic, and decreased after the thinning of the cratonic lithosphere of South China. Our results reveal a consistent structural and topographic change of regional extension and shed light in the coupling of deep and surface response to the cratonmodification and destruction.
How to cite: Liu, T., Chu, Y., Lin, W., Lei, Y., Guo, Y., and Guo, L.: Late Mesozoic extension and denudation of the South China Block: Insights from low-temperature geochronology into the differential evolution of detachment faults, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14334, https://doi.org/10.5194/egusphere-egu25-14334, 2025.
During orogenesis the initial asymmetry of subduction induces asymmetry of continental collision regarding collisional structure, slab geometries, partitioning of crustal shortening and eventually indentation of a stiffer and cooler continent into a relatively warmer and softer continent. After collision and indentation, extrusion and exhumation of deep metamorphic and plutonic rocks are diagnostic processes to evaluate the extent of asymmetry and the long-term structural evolution along and across the continental suture.
An excellent place to study such highly asymmetric patterns are the distinctly non-cylindrical European Alps, an archetypal example of indentation. There, indentation of relatively stiff Adriatic lower crust and upper mantle into the weaker continental Eurasian plate led to unroofing of the Penninic Lepontine dome, as well as strike-slip motion along the Insubric Line. Late-stage collision led to a highly asymmetric exhumation pattern with relative vertical displacement across the fault in the range of 15 (±5) km. The brittle faulting and exhumation history has so far received only little attention, and particularly S of the Insubric Line, large-scale interpretations of cooling and exhumation are based on very little quantitative knowledge. Exploring the faulting and exhumation history of this suture by applying multiple geo- and thermochronometers spanning temperatures from ca. 50 to 450 °C on both sides of the fault is the focus of this project.
(U-Th)/He apatite and zircon dating on more than 50 samples and fission track dating on 25 samples was applied along densely spaced horizontal as well as vertical transects across the Insubric Line. (U-Th)/He apatite ages, which monitor cooling below ca. 80 °C, from north of the fault line prominently cluster around 8-12 Ma. Apatite fission track (closure temperature of ca. 110 °C) as well as zircon (U-Th)/He ages (ca. 210 °C) are only slightly older. Modelling these thermochronological data point to a Late Miocene phase of more pronounced cooling and exhumation of the Lepontine dome than previously assumed. Thermochronological data of Southalpine samples from the immediate vicinity of the fault line record a similar cooling pulse, indicating either joint late-stage exhumation or a heating pulse invoking resetting of Southalpine units due to Lepontine updoming. U-Pb apatite data, recording higher temperature cooling below ca. 450 °C clearly diverge, yielding Permian ages in the south but Oligocene to Early Miocene ages in the north.
Additionally, the seismotectonic evolution of the Insubric fault is targeted by U-Pb dating on pseudotachylites and mylonites. This methodically new approach yields ages clustering at 30 and 16 Ma for a Southalpine pseudotachylite. The signal was measured for a fine-grained mineral assemblage containing U-bearing phases such as apatite, epidote and titanite. The older age cluster corresponds to the phase of major Lepontine updoming, which we confirmed by mylonite dating. The younger age is in line with published Ar-Ar pseudotachylite data (Müller et al., 2001). These initial data suggest that this method could be a valuable tool for dating palaeoseismic events.
Müller, W., et al. (2001). Geochronological constraints on the evolution of the Periadriatic Fault System (Alps). Int J Earth Sci, 90(3), 623-653.
How to cite: Heberer, B., Rahn, M., Gerdes, A., Holzner, E., Czepl, A., Neubauer, F., Dunkl, I., and von Hagke, C.: Assessing the 4-D evolution along and across the Insubric Line in the European Central Alps using a multi-method geo- and thermochronological approach, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16051, https://doi.org/10.5194/egusphere-egu25-16051, 2025.
The tectonic history of Central Europe, located within the interior of the Eurasian plate, is characterised by episodic fault reactivations extending into the Cenozoic. Determining the exact timing of repeated activity along continental intraplate faults is key to understanding the underlying forces driving lithospheric deformation, mantle convection, and geodynamic processes. In particular, lithospheric flow has been proposed as a mechanism capable of reactivating pre-existing fault zones, but its contribution to deformation in Central Europe is not yet well-constrained.
The Variscan Bohemian Massif provides a key setting for this study, with granitic plutons featuring a complex structural and lithological architecture that reflects a prolonged history of deformation. The area is predominantly composed of 312–325-Ma-old granitic rocks intruded into the metamorphic basement during the Variscan orogeny. These rocks are crosscut by numerous fault zones, including the prominent NW–SE-striking Danube fault zone, which has been periodically reactivated under varying stress regimes. Despite its young morphology, the post-Variscan deformation history of the Danube fault zone remains poorly constrained.
By integrating 40Ar/39Ar thermochronology with U-Pb dating of calcite slickenfibres and K-Ar dating of illite from fault gouges in nine different quarries in bedrock northeast of the Danube fault, we reconstruct the temporal and kinematic evolution of these faults. Our results reveal a multi-phase reactivation history, with significant tectonic activity persisting into the Cenozoic. 40Ar/39Ar analysis of K-bearing minerals from deformed host rock yielded the oldest dates, ranging from 232 to 331 Ma, with K-feldspars showing the largest intra-outcrop variations of up to 10 Myr, likely indicating localised resetting of the 40Ar/39Ar clock. K-Ar dates of illite, spanning from 173.2 ± 4.0 Ma to 204 ± 5.3 Ma, reveal evidence of brittle deformation resulting in clay gouge formation. Complementary U-Pb dating of synkinematic calcite slickenfibres on subsidiary fault planes up to 10 km from the main fault, with ages ranging from 45.7 Ma to 0.82 Ma, provides precise temporal constraints and preliminary insights into the timing of deformation. The complementary analysis of mineral parageneses within the dated faults reveals multiple phases of mineral formation and distinct fluid compositions, indicating varying low temperature and pressure conditions (50 – 200 °C; <1.2 GPa). We observed a transition of the Danube Fault from higher-temperature deformation (200–300°C) in the Triassic to near-surface faulting and fluid activity (<150°C) during the Cenozoic. The thermal evolution inferred from our detected mineral assemblages aligns with previously obtained Apatite Fission Track (AFT) ages, indicating low-temperature thermal events (<120°C) related to near-surface exhumation processes.
Our results underscore the importance of detailed analysis of deformation inventory in intraplate setting over geological timescales. The temporal and kinematic data from this study provide a critical contribution to refining the timing and constraining the duration over which currently available stress field models are applicable. Additionally, these data offer a framework for understanding the evolution of intraplate fault systems through integrated radiometric, petrological, and geochemical analyses.
How to cite: Ludat, A. L., Aßbichler, D., Friedrich, A. M., Hofmann, F., Bolhar, R., Hahn, T., and Zwingmann, H.: Unravelling Fault Reactivation History: Geochronological Insights from a Major Intraplate Fault in the Bavarian Forest, Germany, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1928, https://doi.org/10.5194/egusphere-egu25-1928, 2025.
We present a new application of a verified method for determining the relative significance of numerical simulation input parameters. The Taguchi method is commonly used in process engineering to reduce the number of experiments necessary to determine the sensitivity of systems to independent variables. We apply this method to thermal-kinetic and thermal-kinematic modeling as a means to efficiently determine the impact of uncertainties associated with primary assumptions for simulation input parameters on model-derived exhumation histories. The rate of rock uplift is important for determining the nature of the evolution of mountain belts, as well as the relative influence of tectonic and surface processes. Interpretation of thermochronometric datasets is already known to depend on a large and variable number of parameters - such as surface topography, geothermal gradient, exhumation rate, erosion, faulting, and rock properties - yet the impact of primary assumptions associated with these parameters is still uncertain. We are specifically interested in which assumptions impact geological interpretations most. Our novel application of the Taguchi method to thermal-kinematic modeling is compared with a full sensitivity analysis for increasingly complex numerical systems, and we find that the method is both as robust as the exhaustive approach and holds the potential for efficiently analyzing the relative influence of a large number of input parameters in complex simulations.
How to cite: Sparks, S. and Hodges, K.: Thermochronometric design of experiments - applications of the Taguchi method and implications for thermal-kinematic model parameter sensitivity analysis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7535, https://doi.org/10.5194/egusphere-egu25-7535, 2025.
Understanding the thermal evolution of sedimentary basins is critical to hydrocarbon accumulation, as it influences basin development, hydrocarbon generation, migration, and the formation of source rocks and reservoirs. While paleothermometry, primarily applied to organic matter and heavy minerals, has traditionally been the standard method for reconstructing basin-scale thermal histories, marine carbonate strata lack conventional paleothermometers, posing a significant challenge. Clumped isotope analysis, however, offers a promising alternative, leveraging temperature-dependent 13C-18O bond reordering influenced by lattice defects. Recent advancements in modeling approaches—such as first-order approximation (Passey et al., 2012), transient defect models (Henkes et al., 2014), paired reordering/diffusion models (Stolper et al., 2015), and continuous first-order reaction models (Hemingway et al., 2021)—have broadened the applicability of clumped isotopes across diverse geological contexts. However, applying clumped isotope solid-state reordering models without constrained thermal history paths may lead to significant discrepancies in simulation outcomes. To improve accuracy and reduce uncertainty, this study integrates fluid inclusion microthermometry, U-Pb dating, and vitrinite reflectance (Ro) to jointly constrain thermal history paths.
The Ordos Basin, a major hydrocarbon-bearing region in northwestern China, has undergone complex tectonic and depositional transformations, particularly during the Caledonian Orogeny, which obliterated sedimentary records from the Late Ordovician to Early Carboniferous periods. To address the challenges of reconstructing its thermal history, this study combines clumped isotope thermometry, U-Pb dating, fluid inclusion analysis, petrography, X-ray diffraction, and carbon-oxygen isotope analysis. Clumped isotope reordering simulations in calcite cements, constrained by in situ U-Pb dating and fluid inclusion microthermometry, reveal Ordovician paleotemperatures of 180–190°C during the Cretaceous. Similarly, reordering simulations in micritic matrices, supported by Ro and fluid inclusion microthermometry, indicate paleotemperatures of 170–200°C during the Caledonian, a period characterized by deep burial and accelerated source rock maturation. These findings provide critical insights into the thermal history of Ordovician strata in the Ordos Basin, offering valuable guidance for hydrocarbon exploration and advancing our understanding of early hydrocarbon generation processes.
Additionally, this study examines core samples from different depositional environments within a single well, utilizing petrography, Sr isotope, and trace element analyses. Variations in Δ47 clumped isotope values among dolomites from distinct depositional settings suggest that factors such as paleo-salinity and microbial sulfate reduction (MSR) significantly influence Δ47 values. By incorporating clumped isotope kinetic models, this study also investigates the impact of microbial activity, pH, and temperature on ancient dolomite formation. These findings provide a theoretical framework for further research into the formation mechanisms of ancient dolomites in sedimentary strata.
How to cite: Du, H., Liu, Y., and Zeng, S.: Application of clumped isotope solid-state reordering to thermal evolution: A case study of Ordovician strata in Ordos Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8103, https://doi.org/10.5194/egusphere-egu25-8103, 2025.
Convergent plate boundaries are among the most dynamic regions on Earth. These active margins, shaped by the interplay of tectonics, erosion, and climate, are characterised by the highest topography and extensive sediment transport across vast distances. In such complex systems, lithology plays a crucial role, not only influencing rock resistance to deformation, erosion, and weathering, but also posing challenges to the application of dating and rate-determination techniques that rely on specific target minerals. Carbonate landscapes, in particular, present additional difficulties in quantifying denudation and exhumation rates due to their unique chemical and physical properties. Additionally, mountain ranges are shaped by processes acting at different timescales, where a combination of techniques with different integration times is needed to define the temporal evolution of the system.
The application of Beryllium (10Be) cosmogenic nuclides for quantifying denudation and uplift rates can help to overcome such limitations. Firstly, the employment of meteoric 10Be in combination with in situ 10Be overcomes limitations posed by lithology (i.e., the dependence of in situ 10Be on quartz and feldspar), as meteoric 10Be does not depend on specific target minerals. Secondly, the integration time of this technique bridges the temporal gap between long-term geological processes revealed by thermochronology (10⁶ yr) and modern geodetic measurements (10¹ yr).
We tested this approach in the Albanides orogenic system, integrating it with geomorphic, topographic, and fluvial analyses to reconstruct the recent uplift and erosional evolution of this region, characterised by numerous lithologies and a complex tectonic history. Basin-wide denudation rates derived using both in situ and meteoric 10Be are used as proxies of regional uplift rates across the belt, bypassing lithological constraints. The results of these complementary analyses revealed a high degree of consistency, reinforcing the reliability of the methodology. Rates ranging up to 1.61 mm/yr indicate rapid erosion of the orogen, while their spatial distribution highlights strong correlations with active tectonic structures and evidence of river network reorganisation. Despite covering different timescales, our findings align with data from thermochronology, incision rates, and geodesy, suggesting that past processes continue to echo in the present landscape dynamics.
This study highlights the value of integrating geomorphological and cosmogenic nuclide data, particularly through the complementary use of in situ and meteoric Beryllium, to untangle the complex interactions between tectonics and surface processes in active orogenic belts characterised by carbonate lithologies.
How to cite: Bazzucchi, C., Crosetto, S., Ballato, P., Wittmann, H., Faccenna, C., Scherler, D., Rossetti, F., and Muceku, B.: Reconstructing uplift through denudation rates in carbonate systems: the Albanian orogen case study, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13241, https://doi.org/10.5194/egusphere-egu25-13241, 2025.
Posters on site: Tue, 29 Apr, 10:45–12:30 | Hall X2
The thermo-tectonic history of an orogenic belt can be investigated using data on metamorphic grade, thermochronology, and structural geology. However, in the strongly deformed and poorly exposed terrains, field observation and structural correlation present challenges that hinder the construction of large-scale structural frameworks. Previous studies demonstrate that LiDAR-based digital elevation model (LiDAR DEM) reveals geomorphic lineaments caused by interactions between planar geological structures and surface processes. The delineation of these lineaments offers a systematic and comprehensive perspective on regional structures, helping to overcome limitations posed by poor exposure.
In this study, we use 3D mapping of LiDAR DEM and relevant datasets, along with field mapping, to investigate the structural architecture of the strongly deformed and metamorphosed south-central Cenozoic Western Slate Belt in the Central Range of Taiwan. Although the metamorphic grade and low-temperature thermochronologic data are well-established in this region, the structural framework remains unclear, and the relationship between metamorphism and tectonic events is still controversial. Our 3D LiDAR mapping reveals two suites of structural lineaments of interest: bedding (Sb) and metamorphic foliation (Sf). Based on their morphology and field validation, Sb is associated with thick-layered metasandstone and metavolcanic layers, while Sf results from fracturing along an east-dipping, pervasive, and penetrative slaty cleavage. The regional pattern of Sb reveals a previously unmapped, approximately 10 km wavelength, west-facing, tightly folded overturned synform, referred to as the 'Siangyang Synform.' The Sf is axial planar to the Siangyang Synform, suggesting that the cleavage and regional-scale fold developed simultaneously, which is supported by field observations.
This study demonstrates the value of integrating 3D LiDAR mapping and field surveys in strongly deformed metamorphosed terrains. While the orientation and regional patterns of thick-layered, competent rocks are difficult to determine through field surveys alone, they are discernible using the stereo view of LiDAR DEM, revealing macroscopic structural features. By integrating the new structural architecture with published RSCM temperature and geochronologic data, the regional geologic framework shows the peak thermal event postdates or synchronize with the syn-orogenic ductile deformation, highlighting the significance of syn-orogenic undethrusting and metamorphism of the Western Slate Belt during the late-Cenozoic arc-continent collision in Taiwan.
How to cite: Chen, Y.-P., Chan, Y.-C., Wang, Y., and Wei, W.-T.: High-resolution 3D LiDAR mapping of geologic structures: Implications for thermo-tectonic history in the Taiwan Slate Belt, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-126, https://doi.org/10.5194/egusphere-egu25-126, 2025.
Over geological time scales, tectonics and climate exert a first-order control on erosion distribution and efficiency, thereby influencing the evolution of fluvio-glacial mountainous landscapes. This is particularly the case in the Patagonian Andes, a tectonically active region spanning more than 1500 km from North to South. The present landscape has been significantly impacted by the action of erosion and tectonics over different glacial/interglacial cycles during the last 5-6 Ma. Rock cooling history for the region has been previously inferred from bedrock low-temperature thermochronology, whose representativeness may be questioned, as large areas are currently inaccessible, notably due to the presence of ice. Here, we make use of glacial deposits (terminal moraines) that are well preserved in the present landscape, to retrieve information on the erosion history of the region assuming that these deposits are representative of the entire glacial catchment. We present the first results of a multi-method approach applied to the General Carrera-Buenos Aires Lake (GCBA) area, including: (1) apatite fission track (AFT) and U-Pb double dating of samples collected within different moraine complexes east of the GCBA lake, and (2) inverse thermal history modeling using our new detrital data and available in-situ low-temperature thermochronological data. The inference of the thermal histories involves the prediction of elevation profiles, the estimation of detrital age distributions, and the inference of a topographic sampling function (TSF) for each detrital sample. Dating of detrital apatites reveal numerous AFT ages that are older than those observed in in situ/bedrock data from the same glacial catchment. Inverse modelling suggests that these older AFT ages are likely to have sourced from areas at high elevation. We further explore the potential causes for the observed differences in age distributions, which may include: (a) potential biases in the separation process, (b) differences in erosion processes through the catchment, (c) differences in sediment transport and storage processes.
How to cite: Gómez, R., Guillaume, B., Gallagher, K., Cogne, N., Nativ, R., and Barrionuevo, M.: Detrital low thermochronology applied to moraine deposits in the central Patagonian Andes , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1728, https://doi.org/10.5194/egusphere-egu25-1728, 2025.
The Tibetan Plateau is currently the widest and highest elevation orogenic plateau on Earth. It formed as a response to the Cenozoic and still ongoing collision between the Indian and Eurasian plates. The Xigaze fore-arc basin is located along the suture zone of both plates, i.e. the Indus Yarlung suture zone in southern Tibet. This area preserves important information related to the late Cenozoic tectonic and topographic evolution of the Tibetan plateau. In this study, apatite fission track (AFT) thermochronology was carried out on twelve sandstone samples from the middle segment of the Xigaze basin and additionally on four sedimentary rocks from the neighboring Dazhuka (Kailas) and Liuqu Formations. Inverse thermal history modeling results reveal that the fore-arc basin rocks experienced episodic late Oligocene to Miocene rapid cooling, which we interpret as the exhumation of these rocks. Taking into account regional geological data, it is suggested that the late Oligocene-early Miocene (~27-18 Ma) cooling recognized in the northern part of the basin was related to fault activity along the Great Counter thrust, while mid-to-late Miocene-accelerated exhumation was facilitated by strong incision of the Yarlung and Buqu rivers, which probably resulted from enhanced East Asian summer monsoon precipitation. Sandstone and conglomerate samples from the Dazhuka and Liuqu Formations yielded comparable Miocene AFT apparent ages to those of the Xigaze basin sediments, indicative of (mid-to-late Miocene) exhumation soon after their deep, early Miocene burial (> ~3-4 km). Additionally, our new and published low-temperature thermochronological data indicate that enhanced basement cooling during the Miocene prevailed in vast areas of central southern Tibet when regional exhumation was triggered by both tectonic and climatic contributing factors. These events ultimately led to the formation of the high-relief topography of the external drainage area in southern Tibet, including the Xigaze fore arc basin.
How to cite: Song, S., He, Z., Su, W., Zhong, L., Zhong, K., Glorie, S., Song, Y., and De Grave, J.: Late Cenozoic cooling history of the Xigaze fore-arc basin along the Yarlung-Zangpo suture zone (southern Tibet): New insights from low-temperature thermochronology , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4183, https://doi.org/10.5194/egusphere-egu25-4183, 2025.
Low-temperature thermochronology dates mineral cooling through the upper crust, enabling us to constrain the rate and timing of landscape evolution over a range of spatial-temporal scales (Reiners et al. 2005). However, constraining recent thermal histories over timescales of 105−106 years at temperature ranges between 25 and 75 oC remains a challenge owing to a lack of temporal resolution from existing thermochronometers. Deciphering recent time-temperature histories (<100 oC, typically encompassing the upper <3 km of the Earth’s crust) is crucial for understanding the interactions between tectonics, erosion and climate over Quaternary timescales. To this end, trapped charge techniques like quartz Electron Spin Resonance (ESR) dating can exploit the low temperature sensitivity (<100 oC) of various paramagnetic defect centres (such as the Al and Ti centres) to determine thermal history over the Quaternary period. Thus, offering the potential to fill this temporal gap that otherwise remains elusive to classical thermochronology.
The potential of quartz ESR thermochronometry has been previously investigated (Scherer et al. 1991; Grün et al. 1999; King et al. 2020 and references therein). However, this method is still in its developmental stages and lacks a robust validation study to calibrate its temperature sensitivity, and thereby the ability of quartz ESR centres to record thermal histories over Quaternary timescales. Towards this objective, we investigate quartz extracted from borehole sediments in the Anadarko Basin (Oklahoma, USA) with a known temperature history (varying vertically from ~30−80 °C; Carter et al., 1998) based on empirical calibration with a stable geothermal gradient. This study presents preliminary investigations on the kinetics of different ESR centres in the quartz samples and examines the challenges and potential of quartz ESR centres in reconstructing temperature histories in natural settings.
References:
Carter et al. 1998. Am Assoc of Petro Geo Bull 82: 291–316. https://pubs.usgs.gov/publication/70020705
Reiners et al. 2005. Rev in Min and Geochem 58 (1): 1–18. https://doi.org/10.2138/rmg.2005.58.1
Grün et al. 1999. J Geophys Res 104(B8): 17531–17549. 10.1029/1999JB900173
King et al. 2020. Geochron 2: 1–15. https://doi.org/10.5194/gchron-2-1-2020
Scherer, T. et al. 1994. KTB Rep. 94-2. B25, Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland, Niedersächs. Landesamt Bodenforsch.
How to cite: Dave, A. K., Kranz-Bartz, M., Jepson, G., Wen, X., Bernard, M., Schmidt, C., Margirier, A., and King, G. E.: Investigating temperature sensitivity of quartz Electron Spin Resonance (ESR) thermochronometry: Insights from the Anadarko Basin (Oklahoma, USA), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10864, https://doi.org/10.5194/egusphere-egu25-10864, 2025.
The interaction between surface processes, climate and tectonics determines the landscape in alpine regions, with lithology playing a key role. Carbonate rocks, which cover a significant portion of Earth’s terrestrial surface, are more sensitive to environmental changes such as dissolution by meteoric waters compared to siliciclastic or crystalline rocks. This distinct sensitivity makes carbonate rocks important in geomorphological studies, particularly regarding erosion rates. However, the factors influencing erosion rates in alpine carbonate areas remain poorly understood, especially over the (sub-)Quaternary period. Existing techniques are not well-suited to measure erosion rates in carbonate minerals over timescales of 10⁶ years due to limitations in sensitivity or applicability to carbonate rocks in alpine regions. This study explores the potential of electron spin resonance (ESR) signals in calcite as a novel thermochronometer to fill the spatial and temporal gap for constraining Quaternary rock cooling and exhumation rates in carbonate mountain landscapes.
An ideal setting for this investigation has been identified in the European Alps (Rhône Valley, Switzerland), where six samples were collected along vertical (~400-1100 m a.s.l., n=3) and horizontal (~400 m a.s.l., n=3) transects. Analysis of dose response and isothermal decay data from ESR signals demonstrates sufficient stability up to 106 years, allowing us to invert low rock cooling rates (~10 °C/Myr). Our study highlights the potential of ESR thermochronometry of carbonate minerals, supported by several key findings: (i) multiple ESR signals with different thermal sensitivities can be measured in a single sample, (ii) high upper dating limits of 106-107 years, (iii) low closure temperatures (<80 °C), enabling the investigation of recent erosion processes, and (iv) the ability to constrain low exhumation rates of <1 mm/yr. By providing a reliable tool for constraining exhumation rates in carbonate mountain regions, ESR thermochronometry can significantly advance our understanding of the complex interactions between tectonics, climate, and surface processes over Quaternary timescales.
How to cite: Kranz-Bartz, M., Kabacińska, Z., Schmidt, C., Dave, A. K., Wen, X., and King, G. E.: Electron spin resonance (ESR) signals in calcite: a novel thermochronometer to constrain carbonate mountain erosion?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12480, https://doi.org/10.5194/egusphere-egu25-12480, 2025.
Electron spin resonance (ESR) dating of quartz minerals offers a significant advantage over luminescence dating because of its later signal saturation. We seek to exploit this to develop a thermochronometry system capable of resolving rock cooling rates throughout the Quaternary. Whereas the luminescence thermochronometry system is limited to areas experiencing very rapid rock cooling (exhumation) of tens of mm/yr, recent studies have shown that ESR thermochronometry can resolve rates of <1 mm/yr over Quaternary timescales (e.g. Bartz et al., 2024). However, the method has not yet been validated against samples with known thermal histories. To this end, we have investigated six known-thermal history samples from the MIZ1 borehole, Tono, Japan. The low-relief Tono region, Japan, underwent Quaternary exhumation at rates of <1 mm/yrand previous luminescence thermochronometry (Ogata et al., 2022) on the same samples yielded saturated signals. Sample borehole temperatures range from 22.7 to 43.8 °C.
The natural trapped-charge concentration of the different samples was constrained using a single-aliquot regenerative dose measurement protocol. As the samples had similar properties, we constructed a standardised growth curve to alleviate measurement times. Signal saturation of the Al-centre occurred at ~60 kGy and at ~7 kGy for the Ti-centre. Whereas the Al-centre exhibited single-saturating exponential growth, the Ti-centre exhibited significant sub-linearity in the low dose region, within which the natural trapped-charge concentrations were interpolated.
The thermal stability of the different samples was measured using an isothermal holding experiment, whereby samples were dosed in the laboratory before being held at fixed temperatures (130 °C, 160 °C, 200 °C, 250 °C), for durations ranging from 4 min up to a cumulative duration of 10 h. As the thermal signal loss of the different samples was similar, we were able to fit all samples to derive a single set of thermal kinetic parameters.
Finally, the data were inverted for borehole temperature using a Monte-Carlo approach. Whereas the Al-centre of all samples recovered borehole temperature within 1s uncertainties, the Ti-centre data failed to recover temperature, yielding temperatures ~20-30 °C above borehole temperature. The cause for this is uncertain but is likely related to the observed sub-linearity of the dose response curves which may be indicative of sensitivity change throughout analysis.
Bartz, M., King, G.E., Bernard, M., Herman, F., Wen, X., Sueoka, S., Tsukamoto, S., Braun, J. and Tagami, T., 2024. The impact of climate on relief in the northern Japanese Alps within the past 1 Myr–The case of the Tateyama mountains. Earth and Planetary Science Letters, 644, p.118830.
Ogata, M., King, G.E., Herman, F. and Sueoka, S., 2022. Reconstructing the thermal structure of shallow crust in the Tono region using multi-OSL-thermometry of K-feldspar from deep borehole core. Earth and Planetary Science Letters, 591, p.117607.
How to cite: King, G., Bossin, L., Kranz-Bartz, M., Wen, X., Schmidt, C., Herman, F., Ogata, M., and Sueoka, S.: ESR-thermochronometry of the MIZ1 borehole, Tono, Japan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15502, https://doi.org/10.5194/egusphere-egu25-15502, 2025.
The North China Craton (NCC) is the oldest block in eastern China. Since it cratonized during the Paleoproterozoic, the NCC experienced a stable tectonic period during the Paleozoic. During the Meso-Cenozoic, the NCC was influenced by three tectonic domains (the Paleo Asian, the Paleo Tethys and the Pacific Ocean). During that time, the NCC experienced multiple deformation events associated with the Indosinian, Yanshannian and Himalayan orogeny. During the Yanshannian phase, the NCC experienced lithospheric thinning and destruction. This was potentially associated with the formation of a plateau surface with a mean elevation of approximately 2000 m. However, Jurassic-Cretaceous basins with sediment thickness reaching up to 2000 meters, and the coal-bearing strata of Jurassic indicate that the NCC was at low elevations and humid climate at that time.
The Luxi terrane is a basement high located in the middle of the eastern NCC surrounded by basins. It composed of the Archean and Proterozoic metamorphic basement, Paleozoic, Mesozoic and Cenozoic strata. We can directly observe the unconformity contact between Carboniferous and Jurassic, Lower Cretaceous and Upper Paleogene. Thus, Luxi terrane is an ideal place to study the tectonic geomorphology evolution in eastern NCC during the Meso-Cenozoic.
In order to understand the evolution of the eastern NCC during the Meso-Cenozoic, we selected 5 sampling transects perpendicular to the NW trend tectonic line to collect samples in different elevation for low temperature thermochronology experiments including apatite fission track and apatite (U-Th)/He dating. Combined with detrital provenance analysis and structural analysis, we reconstruct the time-temperature history of the NCC
First apatite fission track results indicate early Jurassic uplift of the NCC. Moreover, based on track length analyses and time-temperature modeling, we show that the samples were subject to elevated temperatures between 160 and 100 Ma. Second, results show that the region was subject to a long-wavelength exhumation phase at approximately 100 Ma. After that, our results indicate a rapid uplift event during the Cenozoic, but the farther north the sample located, this uplift occurred more earlier and slower.
How to cite: Zhou, Q., von Hagke, C., Liu, Y., Guan, Q., Liu, B., Yuan, J., Chen, Y., Zhou, Z., and Du, R.: Mesozoic to Cenozoic denudation and uplift process in Luxi Terrane, North China Craton, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16752, https://doi.org/10.5194/egusphere-egu25-16752, 2025.
The topography of mountain belts results from complex variations and interactions between tectonic, climatic and erosional processes. In particular, glaciations result in heterogenous incision along and across mountain valleys. The European Alps have been periodically extensively glaciated since the late Pliocene-Quaternary; however, the impact of these glaciations on the evolution of both orogen-scale and valley-scale relief development and erosion remains disputed. One reason for that is the lack of temporal resolution on timescales of 105 to 106 years.
The low-temperature apatite (U-Th)/He (AHe) thermochronometric system is sensitive to the past shape of the near-surface 65 to 85 °C isotherm, which, at a corresponding depth of ∼2 to 4 km below the surface, follows the approximate shape of the landscape at the time. This feature allows deriving the evolution of topography following the time that rock samples cooled through the isotherm. Thus, provided a well understood tectonic rock-uplift history and suitably distributed ages covering the Pliocene-Quaternary period, AHe data can be used to model the glacial impact on mountain morphology.
The Tauern Window in the Eastern European Alps presents an ideal natural laboratory for this approach, as (1) its rapid tectonically driven exhumation until ~8 Ma is well documented in literature, and (2) there is clear glacial overprinting and relatively high relief within its valleys. Here, we present four new AHe elevation profiles along valleys of differing sizes and orientations in the Western Tauern Window, with AHe ages ranging from ~1.4 to 18.2 Ma.
AHe ages generally increase with elevation, with a prominent and rapid Pliocene-Quaternary exhumation signal recorded in the thermal histories of the valley bottom samples only. We interpret this to signify that regional tectonics alone cannot explain the full exhumation history of the region. We further test this hypothesis, using 3D thermo-kinematic inverse modelling in PecubeGUI to quantify the timing and amount of focused glacial valley deepening. These models are also used to predict the youngest thermal history information, or “edge age”, that we can expect when using the higher-resolution apatite 4He/3He methodology in this area in the future.
How to cite: Wapenhans, I., van der Beek, P., Colleps, C., Bernard, M., Gong, L., and Amalberti, J.: Modelling Pliocene-Quaternary landscape evolution recorded by low-temperature thermochronology in the glacially overprinted Tauern Window, Eastern European Alps, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17327, https://doi.org/10.5194/egusphere-egu25-17327, 2025.
Throughout the Cenozoic, the rock uplift of the Calabrian Arc has been strongly influenced by the retreat of the Ionian slab, where a rollback subduction process has been ongoing since Paleogene times. This complex geological setting has resulted in diverse geodynamic processes, including active extension, mantle dynamics, and the potential influence of slab tearing contributing to the uplift of the Calabrian Arc. Within this geodynamic setting, the topography of the Sila Massif is characterized by an exceptional combination of high elevation and an extensive plateau surface. Such landforms represent strong evidence for recent uplift that has not been fully compensated by erosion. This, along with the possible influence of an underlying tear fault, provides a crucial window into the complex interplay between subduction-controlled tectonics, uplift and erosional response.
Here, we used (U-Th)/He low-temperature thermochronology to investigate the cooling history of the Sila Massif, aiming to constrain the timing and rates of exhumation and thereby elucidate the dominant drivers of exhumation. Our preliminary results reveal higher and potentially more variable long-term erosion rates since the Mid-Miocene than the previously estimated 0.1 km/Myr. These elevated exhumation rates require re-evaluating the dominant tectonic drivers within the Calabrian Arc.
By analyzing the spatial and temporal patterns of exhumation derived from our thermochronological data, we can evaluate the relative contributions of different tectonic processes. Here, we discuss the influence of the Catanzaro deep-seated fault in correlation to the disparate evolution of the Sila Massif and the rest of the Calabrian Arc. Our findings provide a new perspective on the influence of deep-seated faults in sculpting the landscape and shaping the evolution of the Calabrian Arc.
How to cite: Villamizar-Escalante, N., von Hagke, C., Friedrichs, B., Heberer, B., Dremel, F., Jörg, R., Gallen, S., and Roda-Boluda, D.: Deciphering the cooling history of the Sila Massif: Insights into the Calabrian Arc tectonic drivers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18329, https://doi.org/10.5194/egusphere-egu25-18329, 2025.
Due to the complex evolutionary history and the limited understanding of the western Junggar region, studies on the genesis and formation environment of volcanic rocks in the Kebai fault zone remain insufficient. This study employs SHRIMP zircon U-Pb dating, as well as geochemical analyses of elements and isotopes, to investigate the eruption age, petrogenesis, and tectonic setting of Carboniferous volcanic rocks in the Kebai fault zone. The U-Pb age of SHRIMP zircon from tuff samples is 316.8±1.7 Ma, while the U-Pb age of basalt LA-ICP-MS zircon is 321.7±1.8 Ma, both of which correspond to the early Late Carboniferous volcanic eruption. Stratigraphically, these volcanic rocks correlate with the Genghis Khan Formation in the region. The volcanic rocks are classified as calc-alkaline, with SiO2 content ranging from 53.46 wt% to 61.57 wt%, TiO2 content from 0.75 wt% to 1.20 wt%, and a K2O/Na2O ratio between 0.10 and 0.66, exhibiting a sodium-rich and potassium-poor signature. Light rare earth elements (LREE) are relatively enriched, while heavy rare earth elements (HREE) are relatively depleted, as evidenced by (La/Yb)N ratios ranging from 2.72 to 7.89. Large ion lithophile elements (LILEs) such as Ba, Th, U, and Sr are enriched, while high field strength elements (HFSEs) such as Nb, Ta, Zr, and Hf are depleted. The δEu values range from 0.17 to 0.35, displaying a weak negative Eu anomaly. The Zr/Nb (29.36–65.60) and Hf/Ta (12.82–30.16) ratios are significantly higher than those of ocean island basalts (Zr/Nb = 3.0–6.0, Hf/Ta = 10–20) and mid-ocean ridge basalts (Zr/Nb = 10–30, Hf/Ta = 8–15). The volcanic rocks exhibit low (87Sr/86Sr)i values (0.703941–0.705675) and positive εNd(t) values (7.5–8.0), indicating a mantle-like isotopic signature. The Zr-Nb, Th/Zr-U/Th, and Ce/Pb diagrams (values ranging from 2.52 to 13.38, mean 4.61) suggest the involvement of subduction-zone fluids during the volcanic formation process. Furthermore, the Hf/3-Th-Ta, Nb×2-Zr/4-Y, V-Ti/1000, and La/10-Y/15-Nb/8 identification diagrams support the conclusion that the volcanic rocks in the Kebai fault zone were primarily influenced by ridge extension and subduction processes, consistent with a backarc basin extensional tectonic environment.
How to cite: Zongquan, Y., Wei, W., Yan, G., and Zongrui, X.: Genesis of Late Carboniferous volcanic rocks in Kebai Fault zone, Western Junggar, Xinjiang: constraints from SHRIMP zircon U-Pb age, whole rock geochemistry and Sr-Nd-Pb isotopes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2111, https://doi.org/10.5194/egusphere-egu25-2111, 2025.
Exhumation plays a crucial role in shaping the evolution and distribution of resource systems in sedimentary basins, affecting mineral and energy resource exploration. Accurate exhumation estimates, derived primarily from empirical equations based on compaction and thermal datasets, are essential but are often compromised by data errors and unquantified uncertainties in model parameters. For instance, model parameters are usually assumed not to be affected by uncertainties despite varying within measurable ranges. Uncertainties from such variation can propagate and compromise the accuracy of exhumation estimates.
This study introduces a novel and refined approach to exhumation estimation using Markov Chain Monte Carlo (MCMC) methods to quantify and address uncertainties in data and model parameters. Using this approach, we developed a workflow for quantifying exhumation magnitudes and their associated uncertainties and applied it to sonic log datasets from the Canning and Bonaparte Basins. The impact of uncertainty propagation on exhumation results was assessed by examining four scenarios: assuming no uncertainty in the model or data, considering data noise without model uncertainty, considering model uncertainty without data noise, and considering model uncertainties and data noise together.
Our study yielded robust exhumation estimates in the Canning and Bonaparte Basins. Comparison with previous studies shows similarities and differences in exhumation estimates for multiple episodes, with discrepancies potentially arising from variations in exhumation models, data quality and coverage. Uncertainty propagation analysis reveals that considering data-related and model uncertainties together produces variable distributions of exhumation estimates with wider uncertainty ranges. Overall, data quality and coverage proved more critical for the accuracy and precision of exhumation estimates than model refinement. Our models can be integrated into basin evolution studies, help refine fluid migration models, and improve understanding of sedimentation and ore preservation to optimise resource exploration in sedimentary basins.
How to cite: Makuluni, P., Hauser, J., and Clark, S.: Assessment of Uncertainty Propagation within Compaction-Based Exhumation Studies Using Bayesian Inference, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15008, https://doi.org/10.5194/egusphere-egu25-15008, 2025.
Posters virtual: Tue, 29 Apr, 14:00–15:45 | vPoster spot 2
EGU25-1368 | ECS | Posters virtual | VPS28
Extensional collapse of the Himalayan orogen in the Late Miocene.Tue, 29 Apr, 14:00–15:45 (CEST) | vP2.20
The collision of the Indian and Eurasian plates ~ 55 Ma formed the Himalaya, one of the youngest mountain belts. This convergence led to two significant metamorphic stages: M1, which occurs under high pressure and low temperature in a thick crust, and M2, resulting from crustal thinning in a high-temperature, low-pressure environment, evolved the gneissic domes. This study provides the first apatite fission track (AFT) and zircon fission track (ZFT) thermochronological record from one of such gneissic domes in the NW Himalaya viz., the Gianbul Dome (GD). The dome is bounded by two extensional shear zones, namely the South Tibetan Detachment System (STDS) dipping towards NE and the Khanjar Shear Zone (KSZ) dipping towards SW. The AFT cooling ages range from 14.2 ± 1.2 to 5.7 ± 1.1 Ma, and ZFT ages range from 22.8 ± 2.2 to 14.6 ± 0.9 Ma. The ZFT ages remain almost constant across the dome, suggesting thermal relaxation during this period, while the AFT ages are young towards the extensional shear zones of KSZ and STDS. The fission-track data, in combination with the published Ar-Ar and (U-Th)/He cooling ages, has been modeled using a thermo-kinematic inverse and forward model to analyze the processes that led to the exhumation of the dome. Various scenarios like river incision, lithology, deformation along faults like Main Himalayan Thrust, Main Central Thrust, STDS, glacier control, and erosion control over exhumation have been tested. Our results suggest that the extension of normal fault is the primary mechanism for the exhumation of the GD. The extension happened in two phases: (a) during the initial normal sense movement along the STDS when the reverse sense of shear was switched to the usual sense of shear during the early Miocene, and (b) during the Late Miocene. The initial phase of extension is a well-recognized phenomenon in the Himalayan orogen that has been explained through models like channel flow or ductile wedge extrusion. However, the first report of extensional activity along the STDS during the Late Miocene allows us to test whether it is a local phenomenon or a regional event that happened in the brittle stage. Thus, we compiled all the published geochronological and thermochronological data of all the prevailing gneissic domes in the Himalayas from west to east and ran the 3D thermokinematic model to assess the exhumation path of the rocks and brittle stage deformation history. Our results suggest that two phases of extension happened in the entire arc of the Himalayan orogen. The first phase facilitated the southwest migration of ductile materials of rocks from mid-crustal depths accompanying the extension because of gravitation, favoring the channel flow concept. The second phase of extensional collapse happened during ~7-3 Ma ago in the brittle stage. We hypothesize that a drop in gravitational potential energy led to the reactivation of extensional faults along the Himalayan arc. Thus, we propose that extensional collapse in the collisional mountain belts is a cyclic phenomenon that happens to attain a stable, steady state of the orogens.
How to cite: Patel, R. K., Adlakha, V., Mukherjee, K., Pundir, S., Pradhan, P., and Patel, R. C.: Extensional collapse of the Himalayan orogen in the Late Miocene., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1368, https://doi.org/10.5194/egusphere-egu25-1368, 2025.
