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The 10Be record in laminated travertines is a potential proxy for reconstructing past solar activity down to the annual scale; however, correcting for the potential influence of climatic or environmental variations remains challenging. Here, we present an annually resolved 10Be record using travertines from Baishuitai, China, covering the period from 1510 to 1701 CE, along with environmental proxies, to evaluate climatic influences and implement corrections to accurately reconstruct solar activity. We demonstrate that the 10Be deposition in travertines exhibits two environmental impacts: the transport efficiency of atmospheric 10Be into travertine and the additional 10Be inflow from overland flow associated with rainfall. We show that these impacts can be corrected based on iron and potassium contents. The resulting corrected record agrees with ice‐core and tree‐ring records, demonstrating the feasibility of using such carbonate sediment 10Be records to reconstruct past solar activity. Plain Language Summary: The travertine 10Be record has great potential as a proxy for high‐resolution reconstruction of past solar activity; however, the methodology for correcting the potential influence of climatic or environmental variations has not been fully established. This study presents a new high‐precision annual 10Be record using travertines from Baishuitai, China, covering the period 1510–1701 CE, together with records of environmental proxies, allowing us to evaluate the climatic influences and establish a methodology for correcting them to facilitate accurate solar activity reconstruction. We find that there are two environmental impacts on the deposition of 10Be in travertine: one is the transport efficiency of atmospheric 10Be into travertine, and the other is the additional 10Be inflow from the runoff following rainfall events, and we use iron (Fe) and potassium (K) contents to correct these impacts. The corrected travertine 10Be record exhibits good agreement with ice‐core 10Be and tree‐ring 14C records, supporting that the 10Be record in Baishuitai travertine reliably reflects the atmospheric radionuclide production rate as regulated by solar activity. This result demonstrates the feasibility of using such carbonate sediment 10Be records to reconstruct annual solar activity and suggests the possibility of extending the annual records further back in time than previously obtained. Key Points: A high‐precision annual record of travertine 10Be from 1510 to 1701 CE was obtained to assess its potential as a proxy for solar activityClimatological and environmental impacts on 10Be deposition were found to be correctable based on the content of trace elementsThe travertine 10Be record corrected for climatological impacts reasonably preserves the decadal and centennial‐scale solar cycles [ABSTRACT FROM AUTHOR]

The nucleosynthetic Cr isotope anomalies provides useful information to trace the source and origin of extraterrestrial samples, but it is usually influenced by high‐energy cosmic rays, and evaluating such effect of cosmic rays in lunar samples is especially important. Those cosmic radiation particles (primary particles) can react with lunar materials, creating many secondary particles. Both primary and secondary particles can produce cosmogenic nuclides on the Moon. Radiation Environment and Dose at the Moon (REDMoon) is a novel GEANT4 Monte‐Carlo model built to simulate the interactions of space particles with the lunar surface and subsurface content. Using this model, we simulate the production of cosmogenic Cr isotopes (50Cr, 52Cr, 53Cr, 54Cr) at different depths of lunar surface, and compare the contribution of different reactions generating these nuclides. The results suggest that spallation reactions are the most important process producing cosmogenic Cr isotopes. We also analyze the relationship between 53Cr/52Cr and 54Cr/52Cr predicted by our model and compare it with different Apollo samples. As previously studied, we also find an approximate linear relationship between ɛ53Cr and ɛ54Cr, where ɛ53Cr (or ɛ54Cr) is the relative deviation from the standard 53Cr/52Cr ratio (or 54Cr/52Cr ratio), normalized to 1/10,000. Furthermore, we reveal a change of this linear relationship in different depths of lunar surface. Besides, we investigate how the slopes can be influenced by exposure age and the Fe/Cr ratio. With these additional factors carefully considered, the comparison between our modeled results and the measurements is better than previous studies. Plain Language Summary: Cosmic rays arriving at the Moon can change the isotopic compositions on the lunar surface including chromium isotopes which can be used to constrain the evolution history of the Moon. Here, we use the particle transport model to simulate the high‐energy particles and the chromium isotopes generated in the lunar material by different cosmic ray sources. We compare different processes producing cosmogenic Cr isotopes and suggest that the spallation reactions play the main role. After taking the effect of solar energetic particles and the decay of cosmogenic 53Mn into consideration, we reach a better agreement between our model prediction and the Apollo lunar samples about the relationship between ɛ53Cr and ɛ54Cr. Such an improved analysis of the lunar cosmogenic nuclides contributes to a better understanding of the origin of the Moon. Key Points: We simulate the production rate of cosmogenic 50Cr, 52Cr, 53Cr, 54Cr in lunar terrain with Radiation Environment and Dose at the Moon modelWe compare the contributions of different processes producing Cr isotopesWe analyze the relationship between 54Cr/52Cr and 53Cr/52Cr constraining lunar evolution models [ABSTRACT FROM AUTHOR]

Abstract The 10Be record in laminated travertines is a potential proxy for reconstructing past solar activity down to the annual scale; however, correcting for the potential influence of climatic or environmental variations remains challenging. Here, we present an annually resolved 10Be record using travertines from Baishuitai, China, covering the period from 1510 to 1701 CE, along with environmental proxies, to evaluate climatic influences and implement corrections to accurately reconstruct solar activity. We demonstrate that the 10Be deposition in travertines exhibits two environmental impacts: the transport efficiency of atmospheric 10Be into travertine and the additional 10Be inflow from overland flow associated with rainfall. We show that these impacts can be corrected based on iron and potassium contents. The resulting corrected record agrees with ice‐core and tree‐ring records, demonstrating the feasibility of using such carbonate sediment 10Be records to reconstruct past solar activity.

Determining the spatial and temporal variations of Pleistocene glaciations is key to understanding present-day climate-driven glacier changes. Glacial chronologies of high-mountain Asia, which are mostly based on cosmogenic 10Be exposure dating of moraine boulders, remain scarce and often inaccurate due to geologically induced age scatter. We present 53 new 10Be exposure ages from rockslides, glacial sediment deposits and glacial erosion surfaces in the southwestern Pamir. In conjunction with previously published 10Be data, we constrain the timing and extent of three major glacial stages in the Pamir. During the Middle Pleistocene, a continuous ice sheet covered most of the Pamir. This stage is older than 200 ka and may have occurred during Marine Isotope Stages (MIS) 8, 10, or 12. The deep valleys of the western Pamir, which contrast with the eastern Pamir plateau, are partly attributed to Middle Pleistocene glacial erosion. Successively less extensive glacial advances occurred during MIS-4/5 (between 60 and 100 ka ago) and during MIS-2 (at 18–22 ka). The last glacial maximum was synchronous in most of the Pamir, except for prolonged glaciation of the Muztagh Ata ice cap until 14 ka ago. Similar to today, Late Pleistocene glaciers were precipitation-limited, with moisture mainly supplied by westerly winds. An episode of increased mass wasting (e.g. Zuvor rockslide: 34 ± 1 ka) and glacier surging correlates with a peak in δ18O values in the Guliya ice core and is attributed to a warmer climate.

The rearrangement of drainage basins provides critical insight into crustal deformation and geodynamic mechanisms. Near the southeastern boundary of the Tibetan Plateau, the Dadu River abruptly shifts from south- to east-flowing, providing important implications for regional tectonogeomorphic development since the mid-Pleistocene. South of the bend, the headwaters of the Anning River occupy an unusually wide valley. Field investigations show that large quantities of fluvial/lacustrine sediments are widespread along the Dadu and Anning rivers and are exposed at their drainage divide. Detrital zircon U-Pb age patterns confirm that these fluvial/lacustrine sediments are the remnants of the paleo-Dadu River, which strongly suggests that the paleo-Dadu River originally flowed southward into the Anning River. The cosmogenic nuclide burial ages of the lacustrine sediments along the Dadu and Anning rivers suggest deposition of these sediments from separate dammed lakes ca. 1.2 Ma ago, ca. 0.6 Ma ago, and ca. 0.9 Ma ago from north to south, respectively. Provenance and burial-age studies indicate that reorganization of the Dadu drainage occurred within the last 0.6 Ma. We propose that this drainage reorganization in southeastern Tibet resulted from progressive convergence between the India and Eurasian plates during the Pleistocene. [ABSTRACT FROM AUTHOR]

Accelerator Mass Spectrometry (AMS) measurements require reliable standards for calibration. Beryllium-10, 26Al, 36Cl, and 41Ca AMS standards that were prepared by the author are used as primary normalization standards in most AMS laboratories worldwide. The expansion of applications and AMS facilities, accordingly an increase in sample measurements, over the last three decades has largely depleted the available stock of 10Be and 26Al standards that were prepared in 2001 as a series known as the "2001 or 01 dilution". We have undertaken the task of making a new series of 10Be and 26Al AMS Standard Reference Materials (SRM) ("2014 or 14" series) that were prepared from the same parent solution used to produce the 2001 standards. Seven different concentrations of 10Be AMS standards were prepared from a stock solution 2001-4 by sequential dilution with (∼10 kg of) 36.5 mg Be/g carrier solution. The 10Be/Be ratios of the new standards are 1.01 × 10−13, 5.02 × 10−13, 2.507 × 10−12, 2.508 × 10−12, 7.523 × 10−12, 1.504 × 10−11, and 2.502 × 10−11. Six different concentrations of 26Al AMS standards were prepared from a stock solution 2001-3 by sequential dilution with a 35.7 mg Al/g carrier solution. The 26Al/Al ratios of the new standards are 1.51 × 10−13, 5.01 × 10−13, 2.501 × 10−12, 7.501 × 10−12, 1.500 × 10−11 and 5.000 × 10−11. Both 10Be/Be and 26Al/Al ratios of the new 2014 SRM were measured by five AMS laboratories; excellent linearity as well as agreement with the 2001 standard were observed. New 2014 10Be and 26Al SRM are available for the AMS community and are being distributed in the same way as the 36Cl and 41Ca SRM. [ABSTRACT FROM AUTHOR]

The depocenters of epicontinental basins usually comprise relatively continuous depositional records, and these can be used in the determination of sediment routing and paleogeographic changes via a set of various geophysical, sedimentological, biostratigraphic and geochronological approaches. although the margins of such basins will have a major role as constraints for that sediment routing, their depositional records are typically scarce and incomplete, posing a common challenge in terms of gaining information about them. the present study focuses on the upper Miocene succession present in the Malé Karpaty Mts., a pre-cenozoic horst dividing the vienna and Danube basins (central Europe). The data gained by facies analysis, biostratigraphy, shallow seismic survey, authigenic 10Be/9Be dating and correlation of archival borehole profiles reveals, that the succession under consideration represents a record of the lake Pannon transgression, which appeared in the study area at ~10.9-10.6 ma. The subaerially exposed granitic massif and middle miocene successions sourced a shoal water delta, which intercalated with waveinduced dunes and open lacustrine muds in brackish sublittoral to marginal littoral environments. the granitic massif was probably also exposed later, during the regression of lake Pannon at ~10.2-10.0 ma, as a result of the progradation of the paleo-Danube delta from the vienna Basin southeastwards. The depositional record of the regressive sequence was documented and dated in well-cores from the nearby Danube Basin margin. The documented scenario of transgression preceding the overall regression of the paleo-danube delta system by a relatively short period is characteristic of several other localities across the Pannonian Basin system, and may imply that the progradation of depositional system caused a base-level rise on account of sediment loading-induced subsidence. [ABSTRACT FROM AUTHOR]

The depocenters of epicontinental basins usually comprise relatively continuous depositional records, and these can be used in the determination of sediment routing and paleogeographic changes via a set of various geophysical, sedimentological, biostratigraphic and geochronological approaches. Although the margins of such basins will have a major role as constraints for that sediment routing, their depositional records are typically scarce and incomplete, posing a common challenge in terms of gaining information about them. The present study focuses on the upper Miocene succession present in the Malé Karpaty Mts., a pre-Cenozoic horst dividing the Vienna and Danube basins (Central Europe). The data gained by facies analysis, biostratigraphy, shallow seismic survey, authigenic 10Be/9Be dating and correlation of archival borehole profiles reveals, that the succession under consideration represents a record of the Lake Pannon transgression, which appeared in the study area at ~10.9–10.6 Ma. The subaerially exposed granitic massif and Middle Miocene successions sourced a shoal water delta, which intercalated with wave-induced dunes and open lacustrine muds in brackish sublittoral to marginal littoral environments. The granitic massif was probably also exposed later, during the regression of Lake Pannon at ~10.2–10.0 Ma, as a result of the progradation of the paleo-Danube delta from the Vienna Basin southeastwards. The depositional record of the regressive sequence was documented and dated in well-cores from the nearby Danube Basin margin. The documented scenario of transgression preceding the overall regression of the paleo-Danube delta system by a relatively short period is characteristic of several other localities across the Pannonian Basin System, and may imply that the progradation of depositional system caused a base-level rise on account of sediment loading-induced subsidence.

We present a multi‐chronometer approach to refine the age of an alluvial fan and to infer sediment transport and deposition history in the Anza Borrego Desert region of Southern California. We measure in situ produced cosmogenic carbon‐14 (14C) from boulders on the fan surface and infrared stimulated luminescence (IRSL) ages from single feldspar grains within the alluvium. Our new IRSL age [5.3 ± 0.5 ka (±1σ)] is in excellent agreement with existing uranium‐series [U‐series; 5.3 ± 0.2 (±2σ)] ages of pedogenic carbonates. The IRSL and U‐series ages show that in situ14C measurements [6.6 ± 1.1 ka (±1σ)] from boulders contain inherited nuclides from prior exposure in the upstream catchment, much like measurements of the longer‐lived nuclide, beryllium‐10 (10Be). However, in situ14C ages are closer to the preferred ages inferred from IRSL and U‐series and with less scatter than comparative 10Be ages. Our data demonstrate that a multi‐geochronometer approach will produce ages of alluvial fan surfaces with the greatest degree of confidence. We then apply the paired 14C and 10Be concentrations to infer the prior exposure and storage duration of the sampled boulders of 3.1 ± 3.2 and 4.6 ± 2.3 Kyr, respectively. A mixture model analysis of the single grain IRSL ages suggests bimodal storage durations prior to remobilization with peaks at ca. 2 and 10 Kyr. We demonstrate that cosmogenic nuclide inheritance and single grain IRSL equivalent dose distributions can provide additional information regarding sediment transport history prior to deposition on the alluvial fan. Plain Language Summary: Alluvial fans are the accumulations of sediments stored at the base of mountains. Sediment accumulates via mechanisms that are episodic in nature. Often sediment is stored in the upstream watershed for periods of time before being delivered to the base of the mountain as an alluvial fan, where it is deposited and subsequently buried by younger fan deposits. The ability to date alluvial fan surfaces and subsurface deposits has profound implications for the use of alluvial fans as climate archives and to determine slip rates along faults that offset alluvial fan surfaces. We present measurements of the cosmogenic nuclides carbon‐14 and beryllium‐10 from boulders from an alluvial fan surface in the Anza Borrego Desert of Southern California, USA, along with measurements of post‐infrared infrared luminescence from sands that underlie the same fan surface. Our results show that the luminescence data appear to yield robust ages for sediment accumulation in the fan. The cosmogenic nuclides data is not directly applicable to fan surface age determination. We further show that combining the two geochronometers also yields information about sediment storage in the upstream watershed and that in some cases, sediment can be stored for a longer period of time. Key Points: In situ cosmogenic carbon‐14 from alluvial fan surfaces can have inheritance regardless of its short half lifeInfrared stimulated luminescence chronology appears to be a robust alluvial fan chronometerGeochronometric information can be inverted for sediment history in a catchment upstream of an alluvial fan [ABSTRACT FROM AUTHOR]

Since the Last Glacial Maximum ∼20,000 years ago, the Antarctic Ice Sheet has undergone extensive changes, resulting in a much smaller present‐day configuration. Improving our understanding of basic physical processes that played important roles during that retreat is critical to providing more robust model projections of future retreat and sea‐level rise. Here, a limited‐area nested ice sheet model was applied to the last deglacial retreat of the West Antarctic Ice Sheet in the Amundsen Sea Embayment (ASE), at 5 km resolution. The ice sheet response to climate and sea‐level forcing was examined at two sites along the flowlines of Pine Island Glacier and Pope Glacier, close to the Hudson Mountains and Mount Murphy respectively, and the simulated responses compared with ice sheet thinning histories derived from glacial‐geological data. The sensitivity of results to selected model parameters was also assessed. The model simulations predict a broadly similar response to ocean forcing in both the central and eastern ASE, with an initial rapid phase of thinning followed by a slower phase to the modern configuration. Although there is a mismatch of up to 5,000 years between the timing of simulated and observed thinning, the modeling suggests that the upstream geological records of ice surface elevation change reflect a response to retreat near the grounding line. The model‐data mismatch could potentially be improved by accounting for regional variations in mantle viscosity, sea‐surface heights and basal sliding properties across the continental shelf. Plain Language Summary: During the last glacial period approximately 20,000 years ago, the West Antarctic Ice Sheet was much larger than today. Since then, it has undergone extensive changes such as retreat and thinning of its glaciers, and currently dominates the contribution to global sea‐level rise from Antarctica. Glacial‐geological studies undertaken in two mountain ranges in the region (the Hudson Mountains and Mt Murphy, close to Pine Island Glacier and Pope Glacier) provided records of the magnitude and speed of those changes. Here we compare those records with model simulations that predict response of the ice sheet to different forcing mechanisms (climate and sea‐level) over the past 20,000 years. We find that the model predicts a similar response to forcing at both study sites, with initially fast thinning followed by a slower phase as the ice sheet shrinks to its modern shape and size. The similarity in behavior at both sites may be due to similar ocean forcing mechanisms affecting both glaciers. When we compare the model simulations with geological records of ice sheet change, we find a mismatch of up to 5,000 years. Improving how ice‐Earth interactions are represented in the model could potentially resolve this mismatch. Key Points: A nested ice sheet model was applied to the last deglacial retreat in the Amundsen Sea sector, Antarctica. Model outputs were compared with ice thinning historySimilar response to forcing across Amundsen Sea Embayment, possibly resulting from similar (ocean) forcing mechanisms in early HoloceneImproved representation of regionally varying Earth‒ice‒sea‐level interactions may resolve model‐data mismatch in timing of ice thinning [ABSTRACT FROM AUTHOR]

Blue ice moraines are common supraglacial landforms in Antarctica and they are considered to record the ice volume fluctuations. In this study, we use photogrammetry and the analysis of multiple cosmogenic nuclides (10Be, 26Al, and in-situ 14C) in boulders on three blue ice moraines to explore the timing of ice volume fluctuations in the Sør Rondane Mountains, Queen Maud Land, and provide insights into the role of sediment sources in the reconstruction of their chronology. In the field, we observe that the blue ice moraines are composed of subglacially and supraglacially transported sediments. Cosmogenic 10Be and 26Al exposure ages of 14 surface samples, collected from boulders on three blue ice moraines, range from 15.4 ± 1.1 to 659.5 ± 33.9 ka. 26Al/10Be ratios vary between 3.53 ± 0.20 and 7.01 ± 0.32, and many of these ratios indicate complex exposure histories. In contrast, among nine in-situ 14C exposure ages, five vary between 4.2 ± 0.1 and 22.0 ± 1.3 ka, and four are saturated. We conclude that the accumulation of these blue ice moraines commenced before or during the global Last Glacial Maximum. Our results indicate that surficial sediment sources can yield exposure ages that are older than real exposure age, and exhibit a wider scatter. This can alter the reconstructed chronology of these landforms. The analysis of in-situ 14C has a high potential in tracking the pace of their evolution, especially since the Last Glacial Maximum.

Abstract As reverse weathering has been shown to impact long‐term changes in atmospheric CO2 levels, it is crucial to develop quantitative tools to reconstruct marine authigenic clay formation. We explored the potential of the beryllium (Be) isotope ratio (10Be/9Be) recorded in marine clay‐sized sediment to track neoformation of authigenic clays. The power of such proxy relies on the orders‐of‐magnitude difference in 10Be/9Be ratios between continental Be and Be dissolved in seawater. On marine sediments collected along a Chilean margin transect we chemically extracted reactive phases and separated the clay‐sized fraction to compare the riverine and marine 10Be/9Be ratio of this fraction. 10Be/9Be ratios increase fourfold from riverine to marine sediment. We attribute this increase to the incorporation of Be high in 10Be/9Be from dissolved biogenic opal, which also serves as a Si‐source for the precipitation of marine authigenic clays. 10Be/9Be ratios thus sensitively track reverse‐weathering reactions forming marine authigenic clays.

A new model of cosmogenic tritium (3H) production in the atmosphere is presented. The model belongs to the CRAC (Cosmic Ray Atmospheric Cascade) family and is named as CRAC:3H. It is based on a full Monte Carlo simulation of the cosmic ray induced atmospheric cascade using the Geant4 toolkit. The CRAC:3H model is able, for the first time, to compute tritium production at any location and time, for any given energy spectrum of the primary incident cosmic ray particles, explicitly treating, also for the first time, particles heavier than protons. This model provides a useful tool for the use of 3H as a tracer of atmospheric and hydrological circulation. A numerical recipe for practical use of the model is appended. Key Points: A new CRAC:3H model of cosmogenic tritium (3H) production in the atmosphere is presentedFor the first time, it provides 3‐D production, also explicitly treating particles heavier than protonsThis model provides a useful tool for the use of 3H as a tracer of atmospheric and hydrological circulation [ABSTRACT FROM AUTHOR]

As reverse weathering has been shown to impact long‐term changes in atmospheric CO2 levels, it is crucial to develop quantitative tools to reconstruct marine authigenic clay formation. We explored the potential of the beryllium (Be) isotope ratio (10Be/9Be) recorded in marine clay‐sized sediment to track neoformation of authigenic clays. The power of such proxy relies on the orders‐of‐magnitude difference in 10Be/9Be ratios between continental Be and Be dissolved in seawater. On marine sediments collected along a Chilean margin transect we chemically extracted reactive phases and separated the clay‐sized fraction to compare the riverine and marine 10Be/9Be ratio of this fraction. 10Be/9Be ratios increase fourfold from riverine to marine sediment. We attribute this increase to the incorporation of Be high in 10Be/9Be from dissolved biogenic opal, which also serves as a Si‐source for the precipitation of marine authigenic clays. 10Be/9Be ratios thus sensitively track reverse‐weathering reactions forming marine authigenic clays. Plain Language Summary: Clay minerals can form on land by the chemical breakdown of rock‐forming minerals, but clays can also form in the ocean. When clay formation takes place in the ocean, CO2 is released. To date, there is no method that can easily measure the amount of clay minerals formed in the ocean. We used two isotopes of the same element, beryllium (Be), with the atomic mass of 9 and 10 to test whether this isotope system can be used to measure marine clay formation. The abundance of these isotopes differs majorly on land and in the ocean. We measured beryllium isotopes in river sediment and ocean‐bottom sediment offshore the Chile coast and compared the ratios of the isotopes (10Be/9Be). The ratio is four times higher in ocean sediment, when compared to river sediment. We interpret this increase to be due to the formation of clay minerals in the ocean, which include the high 10Be/9Be ratio during their formation. We conclude that the beryllium‐isotope system can be used to measure the formation of even very small amounts (less than 2%) of marine clay minerals. This is important, as the clay‐forming chemical reactions release CO2 which has a long‐term effect on global climate. Key Points: We explored the potential of the beryllium isotope ratio to track neoformation of marine authigenic claysBeryllium isotope ratios increase fourfold from riverine to marine sediment due to the presence of marine Be incorporated in authigenic clayBeryllium isotope ratios sensitively track reverse‐weathering reactions forming marine authigenic clays [ABSTRACT FROM AUTHOR]

Cosmogenic nuclides contained in the annual layers of natural materials record temporal variations in the galactic cosmic ray flux. 14C in tree rings and 10Be in ice cores from polar regions are often used to retrieve accurate histories of galactic cosmic rays. However, the variation in 14C produced in the atmosphere is strongly attenuated in the carbon cycle and the amplitude of decadal scale variations in tree rings is approximately 0.2‰. In the case of 10Be in ice cores, the variation remains at a relatively large amplitude; however, the records are accompanied by dating uncertainties. Another material that contains 10Be is sediment in continental areas. Terrestrial carbonate deposits sometimes form clear annual layers; however, detailed analyses on such deposits have not yet been widely conducted. Therefore, we evaluate the possibility of retrieving information concerning the galactic cosmic ray flux from the terrestrial carbonate deposits. In this paper, we report our preliminary results obtained from the measurements of 10Be in travertine and tufa samples from South China. We find that the 10Be flux obtained from the travertines is comparable to the level produced by galactic cosmic rays and that travertines might have potential as a tool for investigating past cosmic-ray variations with annual resolution. [ABSTRACT FROM AUTHOR]

We present a new in-situ cosmogenic 14C extraction system developed at ETH Zürich. This system quantitatively extracts 14C produced in quartz by cosmic rays using a high temperature extraction procedure. A key improvement of the new extraction system is the implementation of largely automated sequences, CO 2 transport in a He flow and the addition of a "dead" CO 2 carrier gas, which ensure highly reproducible operation while limiting the required operator attendance. Intercomparison quartz samples were routinely measured over a year of operation and yield 14C concentrations of 7.27 (±0.03) · 105 at/g quartz for CRONUS-A (n = 7) and 1.24 (±0.17) · 104 at/g quartz for CRONUS-N (n = 4). The excellent performance of the new system is highlighted by low procedural blanks of ca. 3 · 104 14C atoms and coefficients of variation for the CRONUS-A and CRONUS-N analyses of only 0.4% and 14% respectively. [ABSTRACT FROM AUTHOR]

The Tashkurgan normal fault in the Eastern Pamir is located at the strain transition zone between the dextral strike-slip faulting of the Karakoram fault in the south and the east-west extension of the Kongur Shan extensional system (KES) in the north. Thus, its tectonic evolution and relationship with the KES and the Karakoram fault carry important implications for the strain partition and deformation history of the Pamirs. However, the Tashkurgan fault lacks systematic documentation of its evolution and its relationship to other regional tectonic structures. In order to constrain the tectonic activity of the Tashkurgan fault, we analyze the landscape and 10Be-derived erosion rates in the footwall of the Tashkurgan fault. Our results reveal that both the values of the geomorphological indices and erosion rates increase from the northern segment of the fault towards the central segment and then decrease again southwards but with a further increase in the southernmost segment. We interpret that this pattern is closely related to the fault-related uplift of the Tashkurgan fault except that the southernmost segment is mainly affected by fractured rocks. These observations together with previous studies suggest that the Tashkurgan fault is the southern segment of the KES and extension along the KES has been initiated from the north and transferred to the Tashkurgan fault through the Tagharma fault. Therefore, we infer that the normal faulting of the Tashkurgan fault, and probably the whole KES, may lack a kinematic connection to the dextral slip system in the south. • Fault connections in the Eastern Pamir are investigated. • Landscape and erosion are studied in the footwall of the Tashkurgan normal fault • Erosion rates and landscape features mirror fault-related uplift • The Tashkurgan fault is the southern part of the Kongur Shan extensional system • Extension along the Kongur Shan extensional system is initiated from the north [ABSTRACT FROM AUTHOR]

During 2015 and culminating in early 2016, we acquired a new Carbon Extraction and Graphitization System (CEGS) from Aeon Laboratories, L.L.C. (hereafter, "Aeon"), and adapted it for in situ cosmogenic sample processing. The Tulane University CEGS (TU-CEGS) is fully automated starting from sample insertion into the tube furnace to generation of graphite material ready for accelerator mass spectrometry cathode preparation. The system implements an integrated sequence of sample processing functions: extraction/collection, purification, measurement, and graphite production, which are all integrated into one unified system. The extraction portion is derived from evolving designs of fusions of quartz via lithium metaborate (LiBO 2) flux. A critical analysis of system design in concert with analysis of process parameters yield a nearly order of magnitude increase in sample throughput with total samples processed in our laboratory (320 since installation) with consistent process blank levels (0.98 ± 0.32 × 105 atoms 14C, n = 26) and secondary standard values (0.4953 ± 0.0012 Fm, n = 8). In this paper we detail system design, process algorithm, and line performance including system blanks and the results from the CRONUS-A (6.12 ± 0.32 × 105 atoms g−1 14C, n = 13) interlaboratory comparison material. [ABSTRACT FROM AUTHOR]

Future changes in sea level will largely be dictated by changes in the world's ice sheets. Yet the magnitude and rate at which these ice sheets will respond to climate change remain uncertain, necessitating a deeper investigation into past ice sheet‐climate interactions. Numerous studies have documented the timing and pattern of Laurentide Ice Sheet margin retreat since the Last Glacial Maximum, but few studies have provided vertical constraints necessary for accurate sea level contribution estimates. Here we present 21 36Cl ages from boulder and bedrock samples along vertical transects spanning ~1,000 m of relief from multiple peaks in the Adirondack Mountains of northeastern New York, USA. Our exposure ages span the Last Glacial Maximum through the last deglaciation, with the highest‐elevation sites (~1,500 m) ranging between 25 and 19 ka, and the lower elevation sites (≤1,300 m) between 16 and 13 ka. These data suggest gradual ice sheet thinning of 200 m initiated at ~20 ka followed by more rapid surface lowering of 1,000 m approximately coincident with Bølling‐Allerød warming. Key Points: The 36Cl exposure ages from the Adirondacks show regional ice sheet thinning historiesThe Laurentide Ice Sheet experienced two‐phase thinning in this region ~21–14 kaGradual thinning was followed by rapid retreat coincident with the Bølling‐Allerød [ABSTRACT FROM AUTHOR]

Abstract An objective of terrestrial in situ cosmogenic nuclide research is to obtain precise and accurate production-rate estimates on the basis of geological calibration sites from a diverse range of latitudes and altitudes. However, a challenge has been to establish production rates on the basis of landforms for which independent ages have been determined directly using absolute isotopic dating techniques. Here we present a 10Be production-rate calibration from a recessional moraine belt located in Rannoch Moor, central Scottish Highlands (56.63°N, 4.77°W; ∼310–330 m a.s.l.). This moraine belt was deposited at the margin of the disintegrating late-glacial West Highland ice field (WHIF) during the final stages of deglaciation. Minimum-limiting 14C dates on macrofossils of the earliest terrestrial vegetation to arrive on the landscape place the timing of moraine abandonment, and hence exposure of morainal boulder surfaces to the cosmic-ray flux, to no later than 12,480 ± 100 calendar years before C.E. 1950 (cal yrs BP). Maximum-limiting 14C dates on marine shells incorporated into basal tills deposited during expansion of the WHIF to its full late-glacial extent place the onset of deglaciation, and thus deglaciation of Rannoch Moor, to no earlier than 12,700 ± 100 cal yrs BP. After removal of a single high-concentration outlier, surface 10Be concentrations of 11 boulders rooted in two sub-parallel moraine ridges exhibit a high degree of internal consistency and affords an arithmetic mean of 6.93 ± 0.24 [x104] atoms g−1 (1σ). This data set yields a site-specific 10Be production rate of 5.50 ± 0.18 at g−1 yr−1, based on the midpoint age 12,590 ± 140 cal yrs BP of the bracketing 14C chronology. Transforming this result to sea-level/high-latitude (SLHL) neutron-spallation 10Be production-rate values using Version 3 of the University of Washington (UW) Online Production-Rate Calculator yields upper and lower bounds, and a mid-point rate. Maximum-limiting SLHL 10Be production rates, based on minimum-limiting 14C age control, are 3.95 ± 0.11 (2.7%) at g−1 yr−1 for the commonly used 'Lm' and 'St' scaling protocols. The corresponding (non-dimensional) correction factor for a reference production rate determined by the LSDn scaling model is 0.79 ± 0.02 (2.7%). Minimum-limiting SLHL reference 10Be production rates, based on maximum-limiting 14C age control, are 3.88 ± 0.11 (2.7%) at g−1 yr−1 (St) and 3.89 ± 0.11 (2.7%) at g−1 yr−1 (Lm). The corresponding correction factor for LSDn scaling is 0.77 ± 0.02 (2.7%). SLHL reference production-rate values based on a midpoint age of 12,590 ± 140 yrs are 3.91 ± 0.11 (2.8%) at g−1 yr−1 (St) and 3.92 ± 0.11 (2.8%) at g−1 yr−1 (Lm). The corresponding correction factor for LSDn scaling is 0.78 ± 0.02. The production-rate calibration data set presented here for Scotland yields SLHL values that agree with those determined from calibration data sets based on directly dated landforms from northeastern North America, the Arctic, the Swiss Alps, the Southern Hemisphere middle latitudes, and from the high tropical Andes. We suggest that this production-rate calibration data set from the central Scottish Highlands, used together with the UW online calculators, will produce accurate 10Be surface-exposure ages in the British Isles. Highlights • We present a 10Be production-rate calibration data set for the central Scottish Highlands. • Calibration landform chronology is constrained by bracketing 14C ages. • Results agree with other distal calibration data from independently dated landforms. • Results are at odds with Scottish calibrations based on indirectly dated landforms. [ABSTRACT FROM AUTHOR]

Abstract We present our first 14C in-situ results for calibration and system blanks from the recently completed Australian Nuclear Science and Technology Organisation (ANSTO) – University of Wollongong (UOW) in-situ 14C extraction system. System performance parameters and quality is evidenced by low 14C blanks and good reproducibility for multiple targets from different reference materials. The 14C extraction scheme exploits the high temperature phase transformation of quartz to cristobalite in order to quantitatively extract the carbon as CO 2. The in-situ 14C extraction system comprises three independently operated and modular units that are used for initial in-vacuo removal of meteoric 14C, followed by offline high-temperature heating of quartz to release trapped cosmogenic in-situ 14C, and finally CO 2 gas purification and mass measurement. The design allows for rapid sample throughput of about 6 samples per week with samples masses ranging between 0.5 and 4 g of clean quartz. Other features include single-pass catalytic oxidation using mixed copper (I,II) oxide as catalyst, use of UHV-compatible components and of vacuum annealed copper tubing. We present results for sets of purified quartz samples prepared from CRONUS-A, CRONUS-R and CRONUS-N inter-comparison materials, with final averages consistent with published values. Following extraction and cleaning, CO 2 gas aliquots for some of the samples were analysed using the ETH Zürich CO 2 gas ion source at the ETH MICADAS AMS facility in addition to CO 2 being graphitised using the ANSTO laser-heated graphitisation micro-furnace and then analysed on ANSTO's ANTARES AMS facility. System blanks using either CO 2 or graphite ion-sources at both facilities are on the order of ∼1 × 104 atoms. [ABSTRACT FROM AUTHOR]

The thick Cenozoic sedimentary sequence of the Linxia Basin contains abundant well-preserved mammalian fossils, which provide significant information on the paleoenvironmental processes and mammalian evolution associated with the uplift and expansion of the Tibetan Plateau. Ambiguous age estimations have been made for some coarse-grained sedimentary units in the basin, which have led to the misinterpretation of biostratigraphic and magnetostratigraphic age models. To resolve these issues, we present radiometric dating of three late Cenozoic sedimentary units ("Liushu", Hewangjia, and Jishi formations) in the eastern Linxia Basin using cosmogenic 26Al/10Be and 10Be/21Ne burial methods. isotope measurements for the upper "Liushu" Formation indicate a 10Be/21Ne burial age of 11.70 ± 0.17 Ma. This age is older than, but not contrary to, recently revised bio-magnetostratigraphic work. The 26Al/10Be burial age of the Hewangjia Formation is 3.06 (+0.36/−0.31) Ma and had been underestimated by post-burial muon production possibility, while the 26Al/10Be burial age of the Jishi Formation is 2.50 (+0.20/−0.18) Ma and had been overestimated due to inherited cosmogenic nuclides from recycled deposits. The new age from the Jishi Formation delays the initial deposition of conglomerates in the Linxia Basin to no earlier than 2.5 Ma and constrains an important episode of tectonic uplift of the northeastern Tibetan Plateau to 2.5–3.1 Ma. The age of the Equus fauna of Longdan is revised to the Early Quaternary (ca. 2.1–1.9 Ma). Our new age determinations significantly refine the terrestrial sequence chronology of the Linxia Basin and associated mammalian faunas of the late Miocene to the early Pleistocene. • Cosmogenic nuclide burial dating is applied in the Linxia Basin. • A 26Al/10Be age for the Jishi Formation is 2.50 (+0.20/−0.18) Ma. • A 26Al/10Be age Hewangjia Formation estimate is 3.06 (+0.36/−0.31) Ma. • A 21Ne/10Be age for the "Liushu" Formation is 11.70 ± 0.17 Ma. • Tectonic uplift of the northeastern Tibetan Plateau occurred ∼2.5–3.1 Ma. [ABSTRACT FROM AUTHOR]

The purpose of the study was to investigate, whether the newly developed laboratory at the Dept. of Geology and Palaeontology (Comenius University in Bratislava, Slovakia) is suitable for processing of samples for authigenic 10Be/9Be dating method. The approach was validated on reprocessing of four samples, which were previously analysed at CEREGE (Aix-en-Provence, France). The samples underwent leaching and resin chemistry. Each sample was triplicated with the preparation of a blank sample. Processed samples were sent to CEREGE for isotopic measurements, which provided 15 values of 10Be/9Be ratio. The obtained values showed a good consistency for each sample, although two subsamples appeared as outliers (one of which was original). Analytical uncertainties are comparable to the original measurements, difference is below 1.5 %. Processing blanks yielded stable values at least three orders of magnitude lower than measured subsample 10Be/9Be ratios, what imply a good workflow conditions. These tests revealed that the new laboratory is suitable for processing samples for authigenic 10Be/9Be dating method. [ABSTRACT FROM AUTHOR]

The Earth surface is modulated by interactions among tectonics, climate, and biota. The influence of each of these factors on hillslope denudation rates is difficult to disentangle. The Chilean Coastal Cordillera offers a strong climate and vegetation gradient from arid and unvegetated in the North to humid and vegetated in the South. A similar (convergent) plate tectonic boundary lies to the West of the Coastal Cordillera. We present eight depth profiles analyzed for in situ -produced cosmogenic 10 Be in four study areas. These profiles reveal denudation rates of soil-mantled hillslopes and the depth of mobile layers. Depth profiles were investigated from both S- and N-facing mid-slope positions. Results indicate the depth of the mobile layers in the four study areas increase from N to S in latitude. When mixing is present in the mobile layers they are completely mixed. In the S- and N-facing hillslopes of each study area, mid-slope positions do not show a systematic change in depth of the mobile layers nor in denudation rates based on cosmogenic depth profiles. From N to S in latitude, modelled denudation rates of hillslopes increase from ∼0.46 to ∼5.65 cm/kyr and then decrease to ∼3.22 cm/kyr in the southernmost, highest vegetation cover, study area. Calculated turnover times of soils decrease from ∼30 to ∼11 kyr and then increase to ∼22 kyr. In this work, the increasing denudation rates are attributed to increasing mean annual precipitation from N to S. However, despite the ongoing increase in precipitation from N to S, the denudation rate in the southernmost location does not continue to increase due to the protective nature of increasing vegetation cover. This indicates a vegetation induced non-linear relationship with denudation rates. [ABSTRACT FROM AUTHOR]

We examine probabilistic elements of how cosmogenic nuclide (e.g., 10Be) concentrations and optically stimulated luminescence (OSL) particle ages are distributed within a soil mantle near a hillslope crest as a consequence of disturbance‐driven transport and particle mixing. We use an Eulerian‐Lagrangian algorithm in which fluctuating particle motions, representing depth‐dependent mixing, are superimposed on a two‐dimensional mean motion. The intensity of mixing is characterized by a Péclet number involving the vertical speed of particles entering the soil mantle at the soil‐bedrock interface, the mechanically active soil thickness, and a particle diffusivity at the soil surface. With weak mixing, the vertical profile of 10Be concentration reflects the strong influence of the mean motion in which particles spend much of their lives in the higher part of the soil column with higher 10Be production rates. With increasing mixing intensity, the profile becomes linear, then uniform, and the vertically averaged concentration is larger than that expected with one‐dimensional motion. With weak mixing, particles possessing a finite OSL age tend to remain near the soil surface; with increasing mixing they become more uniformly distributed with depth. Depth‐interval‐averaged OSL ages increase linearly with depth and then become uniform with strong mixing. With moderate to strong mixing, the probability distribution of OSL ages is approximately exponential with an average much less than the mean residence time of particles. The formulation is consistent with profiles of 10Be concentrations and interval‐averaged OSL particle ages compiled from published data, suggesting moderate to strong mixing in the cases examined. [ABSTRACT FROM AUTHOR]

Although several authors have pointed out the importance of earth surface process to passive margin escarpments relief evolution and even drainage rearrangements, the dynamics of a consolidated capture area (after a drainage network erodes the escarpment, as the one from the Itajaí-Açu River) remain poorly understood. Here, results are presented from radar elevation and aerial imagery data coupled with in-situ-produced 10 Be concentrations measured in sand-sized river-born sediments from the Serra Geral escarpment, southern Brazil. The Studied area's relief evolution is captained by the drainage network: while the Itajaí-Açu watershed relief is the most dissected and lowest in elevation, it is significantly less dissected in the intermediate elevation Iguaçu catchment, an important Paraná River tributary. These less dissected and topographically higher areas belong to the Uruguai River catchment. These differences are conditioned by (i) different lithology compositions, structures and genesis; (ii) different morphological configurations, notably slope, range, relief; and (iii) different regional base levels. Along the Serra Geral escarpment, drainage features such as elbows, underfitted valleys, river profile anomalies, and contrasts in mapped χ-values are evidence of the rearrangement process, mainly beheading, where ocean-facing tributaries of the Itajaí-Açu River capture the inland catchments (Iguaçu and Uruguai). The 10 Be derived denudation rates reinforced such processes: while samples from the Caçador and Araucárias Plateaus yield weighted means of 3.1 ± 0.2 and 6.5 ± 0.4 m/Ma respectively, samples from along the escarpment yield a weighted mean of 46.8 ± 3.6 m/Ma, almost 8 times higher. Such significant denudation rate differences are explained by base-level control, relief characteristics, and the geology framework. The main regional morphological evolutionary mechanism is headward denudation and piracy by the Itajaí-Açu River tributaries. As the escarpment moves from east to west, Itajaí-Açu River tributaries develop, leading to regional relief lowering and area losses within the Iguaçu and Uruguai catchments. Such processes were accelerated since Itajaí-Açu tributaries reached into sedimentary and volcanic rocks. From this moment on, Serra Geral became the main hydrographic divide between the ocean- and inland facing-catchments in the area. [ABSTRACT FROM AUTHOR]

Production rates are a cornerstone of in situ cosmogenic nuclide applications, including surface exposure dating, erosion rate/denudation rate estimates, and burial dating. The most common approach for estimating production rates is to measure cosmogenic nuclide samples from sites with independently well-constrained exposure histories. In addition, while researchers attempt to minimize the effects of erosion through careful site and sample selection, it can be present at some unknown level in certain sites. We present a general Bayesian methodology for combining information from the nuclide concentrations, the exposure history, and the possibility of erosion, to determine the production rate at a given site. Then, we use another Bayesian approach to combine the results from the various sites. Cosmogenic 3 He is an ideal test-bed for our Bayesian approach. It has the most calibration sites of the commonly measured cosmogenic nuclides, and there is evidence for the effect of erosion on some of the sites. Our approach largely reconciles previous discrepancies between sites of widely varying age, even at latitudes where geomagnetic effects are significant. With the canonical Lal/Stone scaling scheme, we derive a global sea level high latitude 3 He production rate of 118 ± 2 atoms g −1  yr −1 when considering olivine and pyroxene together. Using the Lifton–Sato–Dunai scaling scheme yields a similar rate of 121 ± 2 atoms g −1  yr −1 . Uncertainties associated with these values are improved over previous studies, due to both reduced scatter among the sites and an approach to combining sites which deemphasizes outliers. [ABSTRACT FROM AUTHOR]

Cosmogenic 10 Be measured in sediments from Northern Range catchments on the island of Trinidad reveals low millennial-scale rates of erosion (average ~ 40 mm/ka) that increase roughly eightfold, from 11 to 92 mm/ka, eastward across the mountain range. These results, in conjunction with an analysis of mountain morphometrics, are consistent with Quaternary east-side-up tilting of the Northern Range, which has occurred recently (~ 100 ka). The highest millennial-scale erosion rates coincide spatially with Quaternary east-side surface uplift (albeit not in magnitude), high modern rainfall rates, low topographic relief, and convex longitudinal stream profiles, indicating transient Quaternary erosion. We interpret that hillslope adjustment and erosion of the Northern Range is buffered from climatic and tectonic forcings by dense tropical vegetation cover, thick saprolite, and porous regolith. Compared with longer-term, thermochronology exhumation rates, we document that an order of magnitude deceleration of and reversal in the locus of erosion and exhumation has occurred during the Pliocene to the Holocene. We suggest that these combined data sets highlight distinct syn- and post-collisional phases of Northern Range development that are related to a major change in relative Caribbean-South American plate motion from oblique convergence to transform motion. Oblique collision during the mid-Miocene likely caused relatively higher rates of and asymmetric exhumation of the Northern Range. Post-collisional mountain-scale tilting is likely caused by a combination of crustal extension in the Gulf of Paria and by deep subsurface lithospheric detachment processes that drives dynamic topography. [ABSTRACT FROM AUTHOR]