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10Be deposition in ice cores is widely used for solar reconstructions, but its interpretation is complicated by volcanic influences. Using the state‐of‐the‐art aerosol‐climate model ECHAM6.3‐HAM2.3‐SALSA2.0: 10Be, we assess the impacts of three major volcanic eruptions: Agung (1963), El Chichón (1982) and Pinatubo (1991). All eruptions enhance stratospheric 10Be sedimentation, increasing atmospheric 10Be below the injection altitude for several months, followed by stratospheric 10Be depletion that takes years to recover. Increases in tropospheric 10Be and deposition coincide with periods of strong stratosphere–troposphere exchange. Aerosol‐induced sedimentation significantly enhances polar 10Be deposition subsequent to the Pinatubo and El Chichón eruptions but plays a limited role after the Agung eruption. Sensitivity experiments reveal that higher SO2 injections generally lead to nonlinear increases in global 10Be deposition. These results underscore the need to account for volcanic influences when interpreting and modeling polar 10Be records following major eruptions.

The Matuyama‐Gauss (M‐G) magnetic polarity reversal is regarded as a fundamental time marker in the stratigraphic division of the Quaternary‐Neogene. However, previous paleomagnetic studies have shown that the M‐G is mainly recorded in the Chinese loess unit L33—a glacial stage (corresponding to marine isotope stage 104, i.e., MIS 104)—which is asynchronous with the timing recorded in marine sediments. Here, we solve this long‐standing debate by exploiting a method to extract reproducible records of paleomagnetic field intensity from Xifeng and Lantian loess profiles with meteoric 10Be. The results showed that for both loess profiles, the 10Be‐derived M‐G boundary is located in paleosol S32 ca. 2,589 ± 3 ka, which corresponds to MIS 103. This is synchronous with that seen in marine sediments, though it is, on average, ∼19 ka younger than the boundary inferred from paleomagnetic measurements from the two profiles, which demonstrates that magnetic overprinting has occurred. Plain Language Summary The Matuyama‐Gauss (M‐G) geomagnetic polarity boundary that occurred at ∼2.6 Ma is usually considered as the key time marker for the division of Quaternary‐Neogene strata because it is globally synchronous. However, previous paleomagnetic studies have indicated that the M‐G boundary is asynchronous between the Chinese loess and marine sediments. This will undoubtedly lead to uncertainties in loess chronology frameworks based on the timing of paleomagnetic polarity reversals and their paleoclimate correlations with global records. To our knowledge, this study is the first to use 10Be‐a proxy for global average paleomagnetic field intensity to trace the M‐G boundary from two loess profiles. We found that the exact positions of the M‐G boundary in both profiles were recorded in S32, which corresponds to MIS 103, indicating that they are synchronous with marine sediment records. Key Points The loess 10Be‐derived M‐G boundary is located in paleosol S32 (corresponding to MIS 103), consistent with marine sediment records The age of the 10Be‐derived M‐G boundary is ∼19 ka younger than the age of paleomagnetic measurements in the same loess sediments The primary magnetic remanence obtained during the M‐G polarity reversal was overprinted by later superimposed magnetic signals

We present a user‐friendly and versatile Monte Carlo simulator for modeling profiles of in situ terrestrial cosmogenic nuclides (TCNs). Our program (available online at http://geochronology.earthsciences.dal.ca/downloads‐models.html) permits the incorporation of site‐specific geologic knowledge to calculate most probable values for exposure age, erosion rate, and inherited nuclide concentration while providing a rigorous treatment of their uncertainties. The simulator is demonstrated with 10Be data from a fluvial terrace at Lees Ferry, Arizona. Interpreted constraints on erosion, based on local soil properties and terrace morphology, yield a most probable exposure age and inheritance of 83.9−14.1+19.1 ka, and 9.49−2.52+1.21 × 104 atoms g−1, respectively (2σ). Without the ability to apply some constraint to either erosion rate or age, shallow depth profiles of any cosmogenic nuclide (except for nuclides produced via thermal and epithermal neutron capture, e.g., 36Cl) cannot be optimized to resolve either parameter. Contrasting simulations of 10Be data from both sand‐ and pebble‐sized clasts within the same deposit indicate grain size can significantly affect the ability to model ages with TCN depth profiles and, when possible, sand—not pebbles—should be used for depth profile exposure dating.

At late Quaternary timescales, offset fluvial terrace risers are among the most common landforms used to determine rates of strike‐slip faulting. Although diachroneity in the age of riser segments on opposite sides of the fault has been noted previously, an unexplored source of uncertainty associated with deriving slip rates from these markers centers on quantifying the size of the displacement uncertainty such diachroneity introduces. To evaluate the impact of riser diachroneity, we investigated the Tuzidun site (37.73°N, 86.72°E) along the Cherchen He reach of the active central Altyn Tagh Fault. The east bank of the channel is flanked by a left‐laterally offset terrace riser. While the measured offset is 54 ± 3 m, geochronologic measurements and analysis of riser topography indicate that the downstream riser segment formed between 6.0 ± 0.8 ka and 5.7 ± 0.4 ka, while the upstream riser segment may have been laterally refreshed as recently as 0.5 ± 0.2 ka. A valley wall on the west bank of the channel places a maximum limit of 38 ± 6 m on the amount of possible lateral erosion of the upstream riser. This bound, in turn, limits the total offset since formation of the downstream riser to range from 54 ± 3 to 89 ± 7 m. Together, these observations bracket the millennial Altyn Tagh Fault slip rate to range from 9.0 ± 1.3 to 15.5 ± 1.7 mm a−1. More generally, this investigation shows that the observed riser displacement does not necessarily correlate with the age of either riser segment (downstream or upstream of the fault) in cases where one segment is displaced while the other is subjected to lateral erosion. If this diachroneity goes undetected, erroneous slip rate measurements are likely to result.

The Foothills Erratics Train consists of large quartzite blocks of Rocky Mountains origin deposited on the eastern slopes of the Rocky Mountain Foothills in Alberta between ~53.5°N and 49°N. The blocks were deposited in their present locations when the western margin of the Laurentide Ice Sheet (LIS) detached from the local ice masses of the Rocky Mountains, which initiated the opening of the southern end of the ice-free corridor between the Cordilleran Ice Sheet and the LIS. We use 10Be exposure dating to constrain the beginning of this decoupling. Based on a group of 12 samples well-clustered in time, we date the detachment of the western LIS margin from the Rocky Mountain front to ~14.9 ± 0.9 ka. This is ~1000 years later than previously assumed, but a lack of a latitudinal trend in the ages over a distance of ~500 km is consistent with the rapid opening of a long wedge of unglaciated terrain portrayed in existing ice-retreat reconstructions. A later separation of the western LIS margin from the mountain front implies higher ice margin–retreat rates in order to meet the Younger Dryas ice margin position near the boundary of the Canadian Shield ~2000 years later.

The sediment delivery from Hainan island into the NW South China Sea during the Quaternary is less well-defined. An investigation into the uplift, exhumation and fluvial geomorphology of the Hainan island is crucial for improving our understanding on the source-to-sink system in this region. In this study, we employed the digital elevation analysis, the stream power incision model and the cosmogenic nuclide isotope analysis to unravel how and why the Hainan island provide sediment to the NW South China Sea. The results show that the average HI values of the main catchments on the Hainan island are below 0.35, which indicates that the rivers on the Hainan island tend to be stable. After mapping the channel steepness index of the Hainan island, a high channel steepness index is constrained in the central and western Hainan island. The χ analysis shows minor variations in χ values across the Hainan island, except of the watershed between the Wanquanhe and Nandujiang rivers, as well as that between the Changhuajiang and Nandujiang rivers, which indicates the potential migration of the river watersheds here. In addition, we carried out the cosmogenic nuclide 10 Be analysis on the river sand from the Hainan island. The spatial distribution of 10 Be concentrations is identified to be high in the west and low in the east. The catchment-averaged erosion rates are quantified to be 35 m/Myr, 42.5 m/Myr and 69.9 m/Myr for the Changhuajiang, Wanquanhe and Lingshuihe catchments, respectively. We also estimated the sediment deliveries from the Changhuajiang, Wanquanhe and Lingshuihe catchments to the Qiongdongnan and Yinggehai Basins to be 0.46 Mt/yr, 0.45 Mt/yr and 0.21 Mt/yr, respectively. We compared our results of the fluvial geomorphology analysis and erosion rate estimates of the Hainan island with those of the Taiwan island. We concluded that the difference of the erosion pattern and river evolution of the Hainan and Taiwan islands may be associated with the variation of the tectonics. Our investigation on the evolution of the Hainan island will improve our understanding on the source-to-sink systems in the NW South China Sea.

Authigenic 10Be/9Be ratios were measured along a sediment core collected in the west equatorial Pacific in order to reconstruct cosmogenic 10Be production variations near the equator, where the geomagnetic modulation is maximum. From 60 to 20 ka, the single significant 10Be production impulse recorded at 41 ka results from the geomagnetic dipole low that triggered the Laschamp excursion. No significant 10Be overproduction signature is recorded at the age of the Mono Lake excursion (∼34 ka). A compilation of authigenic 10Be/9Be records obtained from sediments was averaged over a 1 kyr window and compared with the 1 kyr averaged 10Be flux record of Greenland ice cores. Their remarkable similarity demonstrates that 10Be production is globally modulated by geomagnetic dipole variations and redistributed by atmosphere dynamics. After calibration using absolute values of the virtual dipole moment drawn from paleomagnetic database, the authigenic 10Be/9Be stack allows reconstructing the geomagnetic dipole moment variations over the 20–50 ka time interval. Between 48 and 41 ka, the dipole moment collapsed at a rate of −1.5 × 1022 A m2 kyr−1, which will be an interesting criterion for the assessment of the loss rate of the historical field and the comparison of dipole moment loss prior to excursions and reversals. After a 2 kyr duration of the minimum dipole moment (∼1 × 1022 A m2), a slow increase started at 39 ka, progressively reaching 5 × 1022 A m2 at 20 ka. The absence of a significant dipole moment drop at 34 ka, the age of the Mono lake excursion, suggests that the duration and amplitude of the dipole weakening cannot be compared with that of the Laschamp. This study provides a reliable basis to model the production of radiocarbon and in situ cosmogenic nuclides and to improve the calibration of these dating methods. Key Points First 10Be/9Be record of the Laschamp‐related 10Be production at the equator Compatibility with ice core Be records: global overproduction at this time A global 10Be‐derived dipole moment record is reconstructed and analyzed

Landslide deposits preserved in the geological record afford opportunities to better inform hillslope and seismic hazard and risk models, particularly in regions where observational records are short. In the Southern Alps of New Zealand, small coseismic landslides are frequent, but the geological record preserves several instances of more substantial (> 1 km3) but infrequent mass failures. With an estimated volume of 27 km3, the giant Green Lake Landslide represents one of the largest subaerial landslides on Earth. Previous work has suggested this deep-seated mass movement was most likely triggered by high-intensity seismic shaking, but that local structural weakness and/or glacial debuttressing may help to explain the anomalously large failure volume. Resolving the potential contribution of the latter is important given predictions concerning alpine deglaciation in the coming decades to centuries. Key to resolution are secure chronologies of landslide emplacement and past glacier change. Here we present in situ cosmogenic 10Be exposure ages from the Green Lake Landslide that suggest an emplacement age of 15.5 ± 0.7 ka. Recent work shows that glacial retreat in the region was underway by 19 ka, indicating that the Green Lake Landslide was emplaced 3–4 kyr after the onset of glacier retreat. Given the geometry of the former confining valley glacier, we expect that the deglaciation-landslide age gap is closer to the upper end of this estimate. If correct, this conclusion places greater weight on the roles of local geological structure and/or a great earthquake as factors contributing to the exceptionally large volume of this event.

We reply to comments by Stratford et al.1 on our article2 ‘The age of fossil StW573 (‘Little Foot’): An alternative interpretation of 26 Al/ 10 Be burial data’, in which we revisit the burial age reported by Granger et al. 3 for the sediments encasing the fossil and the data on which this was based.

Cosmogenic Isotopes are produced in the Earth's atmosphere due to the interaction of galactic cosmic rays with nuclei of atmospheric atoms. Among others, the 10Be concentration in ice cores depends on the galactic cosmic ray flux outside of the Earth's magnetosphere and provides therefore a unique tool to investigate the solar modulation over very long time periods. In this study we investigate the importance of different local interstellar proton spectra often used in literature obtained outside of the Earth's magnetosphere. In order to parameterize the heliospheric modulation we apply the force‐field solution using individual local interstellar proton spectrum (LIS) model dependent ϕ values. Thus among atmospheric and magnetospheric processes, the 10Be concentration depends on an interplay of the different LIS and their modulation parameters. Since 10Be measurements do not provide any spectral resolution, PAMELA data have been used for a comparison with the calculated spectra and to provide the model dependent modulation parameters during the solar minimum in July 2006. Within the limitation of the force‐field solution and the freedom in parameter space, all LIS lead to a reasonable agreement with the data. Taking the LIS dependency of the modulation parameter into account, we derive linear equations to convert the individual ϕ between the different LIS. The conversions used here are then applied to a long‐term reconstruction of ϕ derived from a record of the cosmogenic radionuclide 10Be. By using the derived LIS conversions, we show that the occasionally observed negative ϕ values in the reconstruction of Steinhilber et al. (2008) vanish if another LIS model is used. In order to estimate other processes which alter this conclusion, the influence of the palaeo‐magnetic field has been included. Thus, if all inner‐heliospheric effects on the 10Be flux would be known, this investigation would have the potential to rule out certain LIS.