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Abstract. Measurements of multiple cosmogenic nuclides in a single sample are valuable for various applications of cosmogenic nuclide exposure dating and allow for correcting exposure ages for surface weathering and erosion and establishing exposure–burial history. Here we provide advances in the measurement of cosmogenic 10Be in pyroxene and constraints on the production rate that provide new opportunities for measurements of multi-nuclide systems, such as 10Be/3He, in pyroxene-bearing samples. We extracted and measured cosmogenic 10Be in pyroxene from two sets of Ferrar Dolerite samples collected from the Transantarctic Mountains in Antarctica. One set of samples has 10Be concentrations close to saturation, which allows for the production rate calibration of 10Be in pyroxene by assuming production–decay equilibrium. The other set of samples, which has a more recent exposure history, is used to determine if a rapid fusion method can be successfully applied to samples with Holocene to Last Glacial Maximum exposure ages. From measured 10Be concentrations in the near-saturation sample set we find the production rate of 10Be in pyroxene to be 3.74 ± 0.10 atoms g−1 yr−1, which is consistent with 10Be/3He paired nuclide ratios from samples assumed to have simple exposure. Given the high 10Be concentration measured in this sample set, a sample mass of ∼ 0.5 g of pyroxene is sufficient for the extraction of cosmogenic 10Be from pyroxene using a rapid fusion method. However, for the set of samples that have low 10Be concentrations, measured concentrations were higher than expected. We attribute spuriously high 10Be concentrations to failure in removing all meteoric 10Be and/or a highly variable and poorly quantified procedural blank background correction. 

Abstract. The multiple-diffusion domain (MDD) model empirically describes the diffusive behavior of noble gases in some terrestrial materials and has been commonly used to interpret 40Ar/39Ar stepwise degassing observations in K-feldspar. When applied in this manner, the MDD model can be used to test crustal exhumation scenarios by identifying the permissible thermal paths a rock sample could have undergone over geologic time, assuming the diffusive properties of Ar within the mineral are accurately understood. More generally, the MDD model provides a framework for quantifying the temperature-dependent diffusivity of noble gases in minerals. However, constraining MDD parameters that successfully predict the results of step-heating diffusion experiments is a complex task, and the assumptions made by existing numerical methods used to quantify model parameters can bias the absolute temperatures permitted by thermal modeling. For example, the most commonly used method assumes that no domains lose more than 60 % of their gas during early heating steps (Lovera et al., 1997). This assumption is unverifiable, and we show that the Lovera et al. (1997) procedure may bias predicted temperatures towards lower values when it is violated. To address this potential bias and to provide greater accessibility to the MDD model, we present a new open-source method for constraining MDD parameters from stepwise degassing experimental results, called the “MDD Tool Kit” (https://github.com/dgorin1/mddtoolkit, last access: 11 October 2024). This software optimizes all MDD parameters simultaneously and removes any need for user-defined Ea or regression fitting choices used by other tools. In doing so, this new method eliminates assumptions about the domain size distribution. To test the validity of our thermal predictions, we then use the MDD Tool Kit (https://github.com/dgorin1/mddtoolkit) to interpret 40Ar/39Ar results from the Grayback Fault, AZ, USA. Although the resulting thermal histories are consistently ∼ 60–75 °C higher than those found in previous studies, they agree with independent observations from apatite fission track, zircon fission track, and (U-Th)/He. 

Abstract In 2023, the first Polar Postdoc Leadership Workshop convened to discuss present and future polar science issues and to develop leadership skills. The workshop discussions fostered a collective commitment to inclusive leadership within the polar science community among all participants. Here, we outline challenges encountered by underrepresented groups in polar sciences, while also noting that progress has been made to improve inclusivity in the field. Further, we highlight the inclusive leadership principles identified by workshop participants to bring to the polar community as we transition into leadership roles. Finally, insights and practical knowledge we gained from the workshop are shared, aiming to inform the community of our commitment to inclusive leadership and encourage the polar community to join us in pursuing action toward our shared vision for a more welcoming polar science future. 

Abstract. We collected a debris-rich ice core from a buried icemass in Ong Valley, located in the Transantarctic Mountains in Antarctica. Wemeasured cosmogenic nuclide concentrations in quartz obtained from the icecore to determine the age of the buried ice mass and infer the processesresponsible for the emplacement of the debris currently overlaying the ice.Such ice masses are valuable archives of paleoclimate proxies; however, thepreservation of ice beyond 800 kyr is rare, and therefore much effort hasbeen recently focused on finding ice that is older than 1 Myr. In Ong Valley,the large, buried ice mass has been previously dated at > 1.1 Ma.Here we provide a forward model that predicts the accumulation of thecosmic-ray-produced nuclides 10Be, 21Ne, and 26Al in quartzin the englacial and supraglacial debris and compare the model predictionsto measured nuclide concentrations in order to further constrain the age.Large downcore variation in measured cosmogenic nuclide concentrationssuggests that the englacial debris is sourced both from subglacially derivedmaterial and recycled paleo-surface debris that has experienced surfaceexposure prior to entrainment. We find that the upper section of the icecore is 2.95 + 0.18 / −0.22 Myr old. The average ice sublimation rate duringthis time period is 22.86 + 0.10 / −0.09 m Myr−1, and the surfaceerosion rate of the debris is 0.206 + 0.013 / −0.017 m Myr−1. Burialdating of the recycled paleo-surface debris suggests that the lower sectionof the ice core belongs to a separate, older ice mass which we estimate tobe 4.3–5.1 Myr old. The ages of these two stacked, separate ice masses canbe directly related to glacial advances of the Antarctic ice sheet andpotentially coincide with two major global glaciations during the early andlate Pliocene epoch when global temperatures and CO2 were higher thanpresent. These ancient ice masses represent new opportunities for gatheringancient climate information.