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Knowledge of the geological history of the Tibetan plateau is critical to understanding crustal deformation process, and the plateau’s influence on climate. However, the timing of Tibetan plateau development remains controversial. The Nima Basin along the Jurassic-Cretaceous Bangong Suture in central Tibet provides well-dated records of exhumation in this area. Here, we present detrital zircon U-Pb, apatite U-Th/He (AHe) and apatite fission track data (AFT) from upper Cretaceous and Oligocene red sandstones and conglomerates in the Nima Basin, as well as from the Xiabie granite in the hanging wall of the basin-bounding Muggar Thrust. 4 granite conglomerate clasts from the above yield zircon U-Pb ages ranging between 114-122 Ma, which likely come from the Xiabie granite. 7 granitoid/sandstone conglomerate clasts yield AHe ages ranging from 21-58 Ma, while AFT ages range from 34-83 Ma. Thermal history inversion modelling for five of the above samples show a consistent rapid cooling from 100 ℃ to 30 ℃ between 50-40 Ma, the cooling rate decreased significantly after 40 Ma. Implications of these data, integrated in the context of previously published data for the wider region (e.g. Rohrmann et al. 2012; Haider et al., 2013; Li et al., 2019) will be discussed. ReferenceRohrmann, A et al., 2012, Thermochronologic evidence for plateau formation in central Tibet by 45 Ma: Geology, v. 40, p. 187-190.Haider, V. L et al., 2013, Cretaceous to Cenozoic evolution of the northern Lhasa Terrane and the Early Paleogene development of peneplains at Nam Co, Tibetan Plateau: Journal of Asian Earth Sciences, v. 70-71, p. 79-98.Li, H. A et al., 2019, The formation and expansion of the eastern Proto-Tibetan Plateau: Insights from low-temperature thermochronology: Journal of Asian Earth Sciences, v. 183, 103975.

Upwelling mantle plumes beneath continental crust are predicted to produce difficult to quantify, modest uplift and denudation. The contribution of permanent and transient components to the uplift is also difficult to distinguish. A pulse of denudation in Britain in the Early Paleogene has been linked, although with some controversy, with the arrival of the proto-Iceland mantle plume. In this contribution we show that combining apatite and zircon (U-Th-Sm)/He and apatite fission track analyses from central west Britain with numerical modeling clearly identifies a pulse of early Cenozoic denudation. The data indicate that rock uplift and denudation were centered on the northern East Irish Sea Basin and 1.0–2.4 km of rocks were removed during the latest Cretaceous-early Paleogene. Uplift and erosion appears to have started a few million years before the earliest magmatism in the region. The regional denudation pattern mirrors the distribution of low-density magmatic rocks that has been imaged in the deep crust. However, the injection of the underplating melt is not enough to account for the total denudation. An additional regional uplift of at least 300 m is required, which is consistent with a transient thermal effect from the hot mantle plume. The rapid exhumation event ceased by ~40 Ma and the data do not require significant Neogene exhumation.

The timing and mechanisms involved in creating the elevated, low-relief topography of the South African plateau remains unresolved. Here we constrain the thermal history of the southwest African plateau since 300 Ma using apatite fission track (AFT) and (U-Th-Sm)/He (AHe) thermochronology. Archaean rocks from the centre of the Kaapvaal Craton yield AFT ages of 331.0 ± 11.0 and 379.0 ± 23.0 Ma and mean track lengths (MTL) of 11.9 ± 0.2 and 12.5 ± 0.3 µm. Towards the southwest margin of the craton and in the adjacent Palaeozoic mobile belt, AFT ages are significantly younger and range from 58.9 ± 5.9 to 128.7 ± 6.3 Ma, and have longer MTLs (>13 µm). The range of sampleAHe ages complements the AFT ages and single grain AHe ages for most samples are highly dispersed. Results from joint inverse modelling of these data reveal that the centre of the craton has resided at near surface temperatures (

Gondwana (Tauride/Kirsehir blocks) and Eurasia (Pontides) derived continental blocks delimit the Haymana basin, central Turkey, to the south and the north, respectively. The boundaries of these blocks define the Izmir-Ankara-Erzincan and Intra-Tauride Suture zones which are straddled by a number of Late Cretaceous to Oligocene marine to continental basins. The Haymana Basin is located at the junction of the IAESZ and ITSZ and comprises Upper Cretaceous to Middle Eocene basin infill deposited in response to the interaction of these blocks. The basin provides a unique opportunity to unravel spatio-temporal relationships related to the timing of late stage subduction history of Neo-Tethys Ocean and subsequent collision of the intervening continental blocks. We have conducted a multidisciplinary study in the region that includes mapping of major structures combined with fault kinematic analyses. E-W striking folds dominate the basin, cross-section balancing of these structures indicates around 25% roughly N-S shortening in the region. Paleostress studies indicate that the basin was initially subjected to N-S to NNE-SSW extension until the middle Paleocene (phase 1) and then N-S directed syn-depositional compression and coeval E-W directed extension until the middle Miocene (phase 2) implying strike-slip deformation and pure shear shortening in the basin. These different deformation phases are attributed to first fore-arc (subduction) basin development then foreland (collision) stages of the basin. Apatite (U-Th)/He dating of 5 samples indicate that exhumation of the SE segment of the basin started in early Oligocene, whereas the NW segment of the basin exhumed in the early Miocene. The differential uplift is possibly related to progressive north-westwards movement of Derekoy basin bounding fault at the north. We propose that the Haymana basin evolved from extensional forearc basin during the late Cretaceous to early Paleocene and foreland basin after the terminal subduction and subsequent collision of Tauride and Pontide blocks.

Atlantic-type continental margins have long been considered “passive” tectonic settings throughout the entire postrift phase. Recent studies question the long-term stability of these margins and have shown that postrift uplift and reactivation of preexisting structures may be a common feature of a continental margin’s evolution. The Namaqualand sector of the western continental margin of South Africa is characterized by a ubiquitously faulted basement but lacks preservation of younger geological strata to constrain postrift tectonic fault activity. Here we present the first systematic study using joint apatite fission track and apatite (U-Th-Sm)/He thermochronology to achieve a better understanding on the chronology and tectonic style of landscape evolution across this region. Apatite fission track ages range from 58.3 ± 2.6 to 132.2 ± 3.6Ma, with mean track lengths between 10.9 ± 0.19 and 14.35 ± 0.22 μm, and mean (U-Th-Sm)/He sample ages range from 55.8 ± 31.3 to 120.6 ± 31.4Ma. Joint inverse modeling of these data reveals two distinct episodes of cooling at approximately 150–130Ma and 110–90Ma with limited cooling during the Cenozoic. Estimates of denudation based on these thermal histories predict approximately 1–3 km of denudation coinciding with two major tectonic events. The first event, during the Early Cretaceous, was driven by continental rifting and the development and removal of synrift topography. The second event, during the Late Cretaceous, includes localized reactivation of basement structures as well as regional mantle-driven uplift. Relative tectonic stability prevailed during the Cenozoic, and regional denudation over this time is constrained to be less than 1 km.

This study tests alternative models for the growth of the Tatry Mountains (Central Western Carpathians) by the application of low temperature thermochronology. Zircon (U + Th)/He ages from the north of the range are mostly between 48 to 37 Ma and indicate cooling prior to the onset of forearc sedimentation in the region (42–39 Ma). In contrast, zircon (U + Th)/He ages in the south of the range are around 22 Ma. Apatite fission track ages across the sampled sites range from 20 to 15 Ma. Apatite (U + Th)/He ages range from 18 to 14 Ma with little variation with elevation or horizontal location. Based on thermal modelling and tectonic reconstructions, these Miocene ages are interpreted as cooling in the hanging-wall of a northward dipping thrust ramp in the current location of the sub-Tatric fault with cooling rates of ~20 °C/Myr at ~22-14 Ma. Modeled cooling histories require an abrupt deceleration in cooling after ~14 Ma to

Apatite (U–Th)/He and fission track data from profiles in western Scotland constrain the timing and magnitude of denudation during the early Cenozoic when the north Atlantic region was the site of intense magmatic activity related to the proto-Icelandic plume. Apatite helium ages vary from 77 ± 8 to 265 ± 27 Ma (± 2σ) at Sgorr Dhonuill, Ballachulish, and from 104 ± 10 Ma to 166 ± 17 Ma at Clisham, Outer Hebrides. At both locations apatite fission track (AFT) ages are older than the corresponding He ages; at Clisham they vary from 189 ± 28 Ma to 242 ± 26 Ma, and from 186 ± 6 Ma to 257 ± 12 Ma at Sgorr Dhonuill. Apatite He ages increase linearly with elevation suggesting that the cooling rate remained constant in the late Mesozoic. However, the apatite He age profile requires a period of rapid cooling after ∼ 100 Ma. Apatite He ages predicted from the AFT-derived thermal histories are indistinguishable from measured He ages for a rapid cooling event of 1 to 10 Myr duration between 61 and 47 Ma at Sgorr Dhonuill and 65 to 49 Ma at Clisham. The combined apatite FT- and He-derived thermal histories constrain the early Cenozoic geothermal gradient at 39 ± 9 °C/km at Sgorr Dhonuill and 19 ± 6 °C/km at Clisham. Amounts of denudation related to the rapid cooling event vary from 1330 ± 230 m at Sgorr Dhonuill to 2250 ± 750 m at Clisham, in agreement with models that predict greater amounts of denudation where magmatic underplating is thicker. However, the direct correlation between underplating-driven surface uplift and denudation may only be apparent and a more complex link between spatial variation of surface uplift and denudation is suggested. The integration of results from multiple low-temperature thermochronometers, combined with inverse and forward modelling, provides a convincing and quantitative method to deduce onshore erosional histories, and provides critical information about the spatial distribution of erosion that cannot be derived from the offshore record.

The present study aims at testing the possibility of using the in-situ cosmogenic burial dating technique on deltaic deposits. The sequence analyzed is exposed along the Ligurian coast (north-west Italy) and is made of proximal marine and continental deposits previously considered Pliocene or Plio-Quaternary in age. In the study area two allostratigraphic units were recognized. The lower unit represents the evolution of a small coarse-grained delta developed in a fjord or embayment environment. The coarsening/shallowing upward trend observed within the sections, from bottom to top, suggests that the delta prograded rapidly in the landward portion of the canyon placed opposite to the paleo-river outlet. Within the deltaic sequence the transgressive and highstand system tracts were recognized. The unit 2 is composed by several alluvial fan systems deposited in small incised valleys developed within the previously, uplifted deltaic deposits and successively incised by a braided river system. In-situ produced cosmogenic nuclides were used in order to date the age of the deposition of the deltaic deposits. Results suggest that the studied deltaic sediments belonging to the unit 1 were deposited between 1,300,000 and 200,000 year ago thus during the Lower to Middle Pleistocene, whereas the unit 2 was deposited during the Middle Pleistocene as a consequence of a tectonically driven uplift phase. Furthermore samples collected within the prograding part of the delta show the higher denudation rates. The obtained results demonstrate that burial ages and related erosion rates inferred from cosmogenic nuclides concentrations can be considered as a very useful tool to reconstruct the sea level changes over the past 1 million year.

The post-Paleozoic tectonothermal evolution of the SW Iberian Variscides is poorly known mainly due to the scarce low-temperature geochronological data available. We have obtained new apatite fission-tracks and apatite (U–Th)/He ages to constrain the Mesozoic and Cenozoic tectonic evolution of this portion of the Iberian Massif located just north of the Betic-Rif Alpine orogen. We have obtained nine apatite fission-track ages on samples from Variscan and pre-Variscan granitoids. These ages range from 174.4 (± 10.8) to 54.1 (± 4.9) Ma, with mean track lengths between 10.3 and 13.9 μm. We have also performed 5 (U–Th)/He datings on some of the same samples, obtaining ages between 74.6 (± 1.6) and 18.5 (± 1.4) Ma. Time–temperature path modeling of these low-temperature geochronological data leads us to envisage four post-Paleozoic tectonically controlled exhumation episodes in the SW Iberian Variscides. Three of these episodes occurred in Mesozoic times (Middle Triassic to Early Jurassic, Early Cretaceous, and Late Cretaceous) at rates of ≈ 1.1 to 2.5 °C Ma− 1, separated by periods with almost no cooling. We relate these Mesozoic cooling events to the formation of important marginal reliefs during the rifting and opening of the central and northern Atlantic realm. The fourth exhumation episode occurred in Cenozoic times at rates of ≈ 3.2 to 3.6 °C Ma− 1, being only recorded in samples next to faults with topographic escarpments. These samples cooled below 80 °C at ≈ 20 Ma at rates of 3–13 °C Ma− 1 due to roughly N–S oriented compressional stresses affecting the whole Iberian plate, which, in the particular case of SW Iberia, reactivated some of the previous Late Paleozoic thrusts.

The apatite (U – Th)/He and fission track thermochronometers are combined to constrain the Mesozoic and Cenozoic denudational history of the Bathurst region in New South Wales. New apatite (U – Th)/He ages across the continental drainage divide range from 83 ± 14 to 114 ± 18 Ma (±2σ), supporting the evidence from previously published apatite fission track (AFT) data that the region underwent a period of rapid denudation during the mid-Cretaceous. The apatite He-derived thermal histories constrain the amount of erosion in the area and suggest that spatial variations in denudation of the Bathurst Batholith correspond to three broad regions with different histories. The area of the continental drainage divide separates the eastern flank where denudation was rapid at 120 – 90 Ma, and >3 km of crust was removed in about 30 million years, from the western flank, where denudation was less rapid and less prominent. The coincidence of some of the AFT and He ages with the timing of continental extension and Tasman ...

Apatite (U–Th)/He and fission-track thermochronometers are combined to constrain models of denudation and escarpment development of the high elevation Eritrean margin along the southern Red Sea. (U–Th)/He ages have been determined for apatites from two coast-perpendicular transects that were previously used for apatite fission-track analysis [E. Abbate, M.L. Balestrieri, G. Bigazzi, Morphostructural development of the Eritrean rift flank (southern Red Sea) inferred from apatite fission track analysis, J. Geophys. Res., 107, B11, doi: 10.1029/2001JB001009, (2002)]. In central Eritrea near Asmara, He ages increase from c. 7 Ma at the coast to 152 Ma on the plateau along a transect. Further south, He ages from the margin border to the base of the escarpment span a narrower range (7 to 12 Ma). One sample from the top of a marginal high (2950 m) yields older ages (22–43 Ma). Forward modeling suggests that the He age distribution across the margin should allow scarp retreat and downwearing mechanisms to be distinguished in the case of a margin formed in the last twenty million years. The distribution of He ages suggests that the escarpment evolved by downwearing and that post-break up erosion of the escarpment was facilitated by in situ excavation rather than parallel retreat. This implies the existence of an inland drainage divide located seaward of the present day escarpment rim. We envisage that the inland divide formed during or immediately after continent break up, and that the eastern marginal belt represents a remnant of the apex structure. The short distance between the eastern marginal belt and the rim (c. 10 km) represents the total retreat of the escarpment. Comparison of the measured He ages from the coastal plain with those predicted from forward modelling indicates that the main phase of post-break up erosion started at about 15 Ma, closer to the initiation of seafloor spreading in the Red Sea than was thought previously.

Seismic data and core from the shallow cartographic Pilzno P-7 borehole were used to construct a new model of the Carpathian orogenic front between Tarnow and Pilzno, in the Pogorska Wola area (southern Poland). The most external, frontal thrust of the orogenic wedge (the Jaśniny structure) was identified as a syn-depositional fault-propagation fold detached above the Upper Badenian evaporites. Its formation was controlled by the presence of mechanically weak foredeep evaporites and by the morphology of the sub-Miocene Meso-Paleozoic foreland plate (Jaśniny and Pogorska Wola palaeovalleys). The frontal zone of the Carpathian orogenic wedge (the Skole thrust sheet and the deformed foredeep deposits of the Zglobice thrust sheet) is characterized by significant backthrusting of the foredeep succession towards the south, and by the presence of a triangle zone, with strongly deformed Upper Badenian evaporites of the Wieliczka Formation in its core. The triangle zone was formed during the latest thrusting movements of the Carpathians. An indication of the existence of the triangle zone in the vicinity of Debica has also been provided by reinterpretation of the archive regional geological cross-section. The youngest foredeep deposits, brought to the surface above the backthrust, have been dated as Sarmatian (NN7 nannoplankton zone), which indicates that the latest thrust movements within the frontal Carpathian orogenic in the vicinity of Tarnow–Debica took place approx. 11–10 million years ago. Thermochronological studies (AFT and AHe) indicated that the foredeep succession drilled by the Pilzno P-7 borehole has not been buried deeper than 1.5–2 km, which is compatible with reconstruction based on the seismic data.

Testing models of orogen exhumation requires precise constraint of the time–temperature paths of the exhumed rocks. The zircon (U–Th)/He (ZHe) thermochronometer has a closure temperature of ~ 140–210 °C, and can provide temporal constraints on the exhumation history of rocks through a thermal range which crucially corresponds the onset of brittle behaviour of an exhuming orogen. We performed ZHe analyses to test the existing contradictory models for the exhumation of the Ligurian Alps. The ZHe ages indicate a very rapid (1.3–6.8 mm/yr) and southward migrating exhumation of the orogen between ~ 32 and 25 Ma. These high exhumation rates are unique within the Alpine belt and cannot be reconciled with existing geodynamic models of the evolution of the Ligurian Alps. We propose a model of tectonic denudation via detachment accomplished in the shallowest crust (

International audience; Thermochronologic data collected along age-elevation profiles are commonly interpreted as recording temporally variant but spatially constant exhumation rates. However, thermochronologic age-elevation relationships are known to be perturbed by topographic effects and potential changes in relief, which are neglected in the inherently 1-D interpretation commonly applied. Such data thus potentially record both the denudation and relief history of the sampled region but extracting this information is challenging. In a companion paper, we develop a methodology for rigorously interpreting thermochronologic age-elevation profiles in terms of exhumation rates and relief development through time, and to independently quantify the resolution of these constraints. Here we test this approach using a thermochronological dataset consisting of apatite and zircon fission-track and (U-Th)/He data, collected at La Meije Peak in the Pelvoux-Ecrins massif (French Western Alps). Our data and models suggest a three-phase exhumation history in the Pelvoux-Ecrins massif, including a pulse of rapid exhumation at ˜ 6-5.5 Ma, preceded and followed by more moderate rates of denudation in the order of 0.3-0.4 km Myr‑ 1. This rapid exhumation event appears to occur coevally in other external crystalline massifs in the Alps but is not detected by qualitative inspection of the age-elevation relationships. Both our synthetic results and inversion of the La Meije data strongly suggest that apatite fission-track age-elevation relationships alone cannot resolve both denudation and relief histories independently and that multiple thermochronometers are required. Combining apatite fission-track and (U-Th)/He ages and, particularly, including fission-track-length data greatly improves the resolution of the inferred exhumation histories. Although denudation rates through time and the timing of rate changes are generally well resolved, our data have insufficient resolution to satisfactorily constrain the relief history. Synthetic results reported in the companion paper suggest that the reason for this limitation is that relief increase through valley carving has been insufficient with respect to the regional denudation rates to be unambiguously extracted from the data.

[1] Several recent studies proposed an important increase in exhumation rate in the western European Alps since circa 5–4 Ma. In order to assess potential spatial differences in exhumation histories, we present new apatite fission track (AFT) and apatite (U-Th)/He (AHe) ages from the central Aar Massif (Guttannen area, Switzerland) and the western Lepontine Dome (Formazza area, Italy). Internal U/Th zoning in apatites explains alpha-ejection-corrected AHe ages that are older than the corresponding AFT ages in this study. A qualitative interpretation of AFT and AHe age-elevation relationships suggests a two-phase (9–7 and 5–3 Ma) exhumation scenario affecting the central Alps, with a stronger expression of the Pliocene signal in the Formazza area. However, a quantitative evaluation of exhumation scenarios using the 3-D heat equation solver Pecube highlights the existence of several other likely scenarios, casting doubt on the validity of a qualitative interpretation of the age-elevation relationships. In Formazza, scenarios suggested by quantitative modeling include continuous denudation at a rate of ∼750 m/Ma and a one-step exhumation rate change from 300 to 1000 m/Ma at 5 Ma. In Guttannen, they include continuous denudation at a rate of ∼400 m/Ma with valley deepening and two periods of higher exhumation rate (increasing from 300 to 700 m/Ma repeatedly at 9–7 and at 5–3 Ma). Contingent upon further flexural isostatic modeling, the magnitude of exhumation recorded in the axial region of the Alps since circa 5 Ma does not appear sufficient to solely explain the denudation recorded in the North Alpine Foreland Basin.

International audience; The long-term evolution of the East Greenland fjord region is investigated using geomorphological and stratigraphical evidence to: (1) assess the nature of landscape modification caused by late Cenozoic ice sheet glaciation; and (2) relate patterns of glacial landscape modification to first-order (i.e. continent-margin scale) topography and geology. Geomorphological and stratigraphical evidence demonstrates evolution of the first-order topography and incision of at least part of the present first-order fjord system by 55 Ma. This hypothesis is tested using apatite (U­Th)/He ages for samples from two bedrock profiles near Kong Oscar Fjord. The thermochronology supports landscape evolution before 55 Ma, followed by relative tectonic stability, because it indicates rapid denudation around the time of rifting that occurred prior to continental breakup (i.e. between 75 and 55 Ma). The nature of landscape modification caused by late Cenozoic glacial erosion appears to have been controlled by first-order topography and geology, with selective ice sheet erosion in areas of high-elevation Caledonian basement and apparently little glacial erosion of low-elevation Mesozoic sedimentary strata. Nevertheless, fjord morphometry demonstrates systematic evolution of the first-order fjord system from confined and overdeepened fjords in Caledonian basement to wider and disproportionately larger fjords in Mesozoic strata. The latter indicates that changes in lithological strength enabled the development of more efficient fjord morphology under full glacial conditions that may have promoted fast ice flow.

[1] First-order topographical features at high-elevation passive margins have the potential to store information about the early stages of continental rifting, which are usually lost in the sediment record. In this study we present a new combination of apatite fission track and (U-Th)/He analyses from two coast-perpendicular traverses to decipher the time of formation and evolution of the escarpment at the southeastern Australian margin. A combination of inverse and forward modeling of the apatite fission track (AFT) and He data indicates that the coast experienced a rapid denudational event starting at 110 ± 10 Ma, at least 15 Myr before seafloor spreading (85 Ma), in agreement with the hypothesis that rifting at magma-poor margins evolves slowly. Thus the enhanced denudation is not related to the synbreakup base level drop, but it may have been related to a thermally driven transient surface uplift. Considerations on isostatic flexure and rigidity of the lithosphere indicate that unless significant synrift brittle movements are assumed to have occurred along margin-parallel faults that are no more visible, the coast must have experienced a higher geothermal gradient than normal. The evolution of the rest of the coastal plain may have taken up to ∼90 Myr, in agreement with numerical models of passive margins evolution. The (U-Th)/He ages across the coastal plain are consistent with an in-place-excavation scenario of a high rift shoulder, and they rule out the possibility of a constant retreat of the escarpment. AFT + He data from the plateau indicate that the highlands remained stable throughout continental breakup, experiencing rates of erosion of 5–10 m/Myr since, at least, 200 Ma.