Application of drone-captured thermal imagery in aiding in the recovery of meteorites within a snow-covered strewn field

The rapid recovery of meteorites mitigates the exposure of astromaterials to the terrestrial environment and subsequent contamination. Modern fireball observatories have enabled the more accurate triangulation of fireball trajectories, which has aided in the location of strewn fields, in the case of meteorite-producing events. Despite this advancement, most meteorite searches still use manual searching to locate any meteorite falls, which is often labor-intensive and has a slow coverage rate (km² day⁻¹). Recent work has begun exploring the application of drone technology to the recovery of meteorites; however, most of this work has focused on falls in arid environments. Our study examines the utilization of drones with thermal imaging technology to aid in the recovery of meteorites that have fallen on a snow-covered field. We created a simulated strewn field that included meteorite specimens as well as Earth rocks with similar properties (“meteowrongs”). Thermal imagery was utilized to determine whether the thermal contrast between meteorites and snow could aid in the identification of meteorites. We found that the thermal contrast was significant enough that meteorites were readily identifiable within thermal images; however, it was not significant enough to distinguish between the meteorites and the meteowrongs. The utilization of thermal imagery in conjunction with visible imagery has the potential to aid in the rapid recovery of meteorites in snow-covered landscapes.     

Coupling multipoint flux mixed finite element methodswith continuous Galerkin methods for poroelasticity

We study the numerical approximation on irregular domains with general grids of the system of poroelasticity, which describes fluid flow in deformable porous media. The flow equation is discretized by a multipoint flux mixed finite element method and the displacements are approximated by a continuous Galerkin finite element method. First-order convergence in space and time is established in appropriate norms for the pressure, velocity, and displacement. Numerical results are presented that illustrate the behavior of the method.     

Copper‐gold mineralisation in New Guinea: Numerical modelling of collision,fluid flow and intrusion‐related hydrothermal systems

Two‐ and three‐dimensional numerical modelling techniques, constrained by key geodynamic data, provide insights into the controls on development of porphyry‐related Cu–Au mineralisation in the Tertiary collision zone of New Guinea. Modelling shows that the creation of local dilation to facilitate magma emplacement can be caused by reactivation of arc‐normal transfer faults, where they cut the weakened fold belt. Additionally, dilation occurs where fluid overpressuring is caused by collision‐related, south‐directed fluid flow being localised into the more permeable units of the Mesozoic passive‐margin sedimentary succession. Rapid uplift and erosion, which may be a mechanism for magmatic fluid release in these systems, is shown to be greatest in the west of West Papua, where the stronger Australian crust acts as a buttress. Within the Papuan Fold Belt, uplift is greatest near the margins, where the weaker fold belt abuts the stronger crust and/or major faults have been reactivated. Increased orographically induced precipitation and erosion exposes the lower parts of the stratigraphy within or on the margins of these uplifted zones. On a smaller scale, 2–D coupled fluid‐flow ‐ thermal‐chemical modelling uses a scenario of fluid mixing to calculate metal precipitation distribution and magnitude around an individual intrusive complex. Modelling highlights the interdependence of the spatial permeability structure, the regional temperature gradient, and the geometry of the convection cells and how this impacts on the distribution of metal precipitation.     

Secular contraction in extreme helium stars and the future of V4334 Sgr

Speculative connections have been made between Sakurai's Object andother hydrogen-deficient stars, principally the RCB stars and [WC]central stars of planetary nebulae. RCBs have also been postulated as the precursors of extreme helium stars (EHes). The question arises to whether Sakurai's Object will evolve down the [WC]-PG1159 evolution track, or the RCB-EHe-HesdO track. From a number of IUE observations, we have measured thesecular contraction rates and pulsation masses of several EHes. These are inconsistent with the predicted contraction rates for helium-shell burning giants produced by a final helium-shell flash (the [WC]-PG1159 track). Although there may be some similarities between Sakurai's Object and some RCBs, if the RCB-EHe conection is valid then these must be superficial rather than structural.     

Laser Ablation (U-Th-Sm)/He Dating of Zircons: Analytical Age Bias and its Consequence for Studying Detrital Zircon Populations

The in situ (U-Th-Sm)/He and U/Pb laser-ablation double-dating procedure is a valuable method that can provide a large dataset relatively efficiently in contrast with conventional bulk helium thermochronometry. In this study, we evaluate the potential age error associated with the double ablation procedure and report the in situ (U-Th-Sm)/He double-ablation dating of 249 zircons from the Fish Canyon Tuff locality. With LA-ICP-MS pseudo-depth profiling and 3D numerical modelling, we show that the concentric double-ablation procedure in minerals with U-Th-Sm zoning can generate a significant (U-Th-Sm)/He age error (positive or negative), resulting in over-scattering and/or an offset of the mean age. Pseudo-depth profiling is insufficient to predict the individual age error, partly because of the superimposed ablations. To evaluate the consequence of this inherent bias, we confront a synthetic age distribution to the error expected for U-Th-Sm zoned zircons analysed with double-ablation (U-Th-Sm)/He thermochronometry. As expected, a strong age bias causes the spreading of peak ages, downgrading the original signal. Yet, the throughput of the ablation-based method can allow intra- and inter-sample peak age identification and comparison, and the coupling of (U-Th-Sm)/He and U/Pb ages extends our ability to deconvolute a multimodal age spectrum.     

Performance studies of the fixed stress split algorithm for immiscible two-phase flow coupled with linear poromechanics

In this work, we measure the performance of the fixed stress split algorithm for the immiscible water-oil flow coupled with linear poromechanics. The two-phase flow equations are solved on general hexahedral elements using the multipoint flux mixed finite element method whereas the poromechanics equations are discretized using the conforming Galerkin method. We introduce a rigorous calculation of the update in poroelastic properties during the iterative solution of the coupled system equations. The effects of the coupling parameter on the performance of the fixed stress algorithm is demonstrated in two field studies: the Frio oil reservoir and the Cranfield injection site.