ALBERT

Description: Tin (Sn) and tungsten (W) behave incompatibly in reduced magmatic systems and may become enriched in late highly-evolved melts. Nonetheless, Sn and W rarely concentrate in the same deposit. In deposits formed by Sn- and W-bearing granites, this separation may be due to the contrasting behavior of Sn and W during exsolution of a magmatic fluid or the scavenging of Sn by silicate minerals. We illustrate the separation of Sn and W for the world-class Zhuxi W skarn deposit (South China). Although tin orebodies have not yet been identified within the Zhuxi deposit, tiny (commonly 〈 20 μm) cassiterite grains are widespread within the endoskarn and the retrogressed exoskarn. We analyzed the W and Sn contents of the magmatic minerals biotite and ilmenite in ore-forming granites and the prograde anhydrous skarn minerals garnet, pyroxene and vesuvianite. Our data show that (i) magmatic ilmenite (65.5–79.1 ppm Sn; 8.7–14.3 ppm W) and biotite (109–120 ppm Sn; 1.3–6.3 ppm W) from biotite monzogranite strongly enrich Sn relative to W, implying that W partitioned more strongly into the magmatic fluids than Sn, (ii) there is 100 Kt non-recoverable Sn within the Zhuxi deposit in addition to the certified 3.44 Mt WO3 reserves, and (iii) W is mainly hosted in scheelite, whereas Sn is dominantly sequestered in prograde skarn minerals, most importantly garnet (76–4086 ppm Sn, 〈 42 ppm W), pyroxene (3–103 ppm Sn, 〈 1 ppm W), and vesuvianite (43–361 ppm Sn, 〈 2 ppm W). The formation of secondary cassiterite requires the release of silicate-bound Sn by alteration of primary skarn minerals, which depends on the availability of magmatic or metamorphic fluids. Deep-seated granites such as those associated with the Zhuxi skarn deposit, which crystallized at 5 km to 12.6 km depth, do not release or mobilize copious amounts of fluid. Therefore, the Zhuxi deposit, like other deep-seated reduced skarn systems shows little alteration and most Sn remains in silicate minerals and is economically non-recoverable. Thus, reduced, deep-seated W skarn systems are unlikely to have associated Sn orebodies even if significant amounts of Sn are present.

Description: In high-precision space geodetic techniques data processing, the mapping function (MF) is a key factor in mapping the radio waves from the zenith direction down to the signal incoming direction. Existing MF products, either site-wise Vienna Mapping Function (VMF1 and VMF3) or grid-wise VMF1 and VMF3, are only available at the Earth surface. For overhead areas, height correction is always required, which is becoming increasingly important with growing airborne aircraft activity. In this contribution, we introduce a novel method aimed at providing a large number of MFs to the user in a simple and efficient manner, while minimizing the loss of precision. The approach effectively represents the vertical profile of the MFs from the Earth's surface up to altitudes of 14 km. In addition, the new model corrects for height in the assessment using the fifth generation of the European Centre for Medium-Range Weather Forecasts ReAnalysis (ERA5) ray tracing calculations for a global 5° × 5° grid with 54 layers in the vertical direction, a total of 8 azimuths in the plane, and 7 elevation angles, for each day in 2021. Specifically, for both polynomial and exponential model of order 2 and 3, the relative residuals are 〈 0.3% for the hydrostatic delay MF coefficient , and 〈 1% for the wet delay MF coefficient . The precision of the new model on the Earth’s surface is evaluated using site-wise VMF1 and VMF3 GNSS (Global Navigation Satellite System) products from Technische Universität Wien. The root mean square error of slant hydrostatic delay and slant wet delay at a 3° elevation angle is approximately 4–5 cm and 2–5 cm, respectively.

Description: Carbonatites and their comagmatic silicate rocks related deposit provide significant resources of rare earth elements (REEs), niobium (Nb) and other elements such as U, Th, Mo, V, Ba, Sr, etc. However, the genesis of mineralization, especially for REEs and Nb, in carbonatite remains enigmatic. Previous liquid immiscibility experiments have demonstrated that both REEs and Nb are preferentially enriched in the silicate conjugate instead of carbonate melts under anhydrous conditions. Nevertheless, ligands other than carbonate ion appear to be abundant due to ubiquity of apatite, baryte, celestine, fluorite and sodalite in carbonate–silicate magmatic systems. Here, we experimentally investigate the trace element partitioning between natrocarbonate and silicate (nephelinite) melts in systems doped with varying amounts of additional F−, PO43−, Cl−, and SO42− ligands (0, 2, 4 and 6 wt%) to understand and constrain the role of ligands. The experiments were conducted at 850 °C and 0.1 GPa using rapid quench cold-seal pressure vessels (CSPVs). A comparison of experimental partition coefficients in this study reveals that the significant amounts F− and PO43− incorporated in the silicate melts can increase the D values for REE by influencing melt structure (DLaCM/SM = 0.85–7.42). In contrast, irrespective of the amount of added Cl− and SO42−, DCM/SM is not affected significantly by these species and the DREECM/SM values remain always lower than 1 (DLaCM/SM = 0.12–0.40). Notably, the DNbCM/SM values are all 〈1, with only one exception containing 6 wt% F. Besides, in all the investigated systems, Ba, Sr, Mo, V, Cs, Rb and Li preferentially partition into the conjugate carbonate melt. All the high field strength elements (Pb, Th, U, Zr, Hf, Nb, Ta), transition metals (Mn, Co, Cu, Zn) and common network formers (Ga, Ge) essentially partition into the silicate melt.

Description: This work studies variations of ionospheric total electron content (TEC) during four distinct solar eclipse events over the Ethiopia region. Dual‐frequency global positioning system (GPS) data obtained from UNAVCO over Addis Ababa (9.036°N, 38.76°E) and Bahir Dar (11.6°N, 37.34°E) stations are used to examine the ionospheric variability during two annular solar eclipses on 15 January 2010 and 1 September 2016, a partial solar eclipse on 4 January 2011, and a hybrid solar eclipse (the eclipse path starts out as annular but later changes to total) on 3 November 2013. The results show a significant decrease in TEC values during the occurrence of the solar eclipses. Specifically, the TEC values are reduced to

Description: An ideal target for geodetic very long baseline interferometry (VLBI) is a strong and point-like radio source. In reality, most celestial sources used in geodetic VLBI have spatial structure. This is as a major source of error in VLBI Global Observing System (VGOS) and also affects legacy S/X observations. Source structure causes a systematic delay, which can affect the geodetic estimates if not modelled or otherwise accounted for. In this work, we aim to mitigate its impact by extending the stochastic model used in the least-squares fitting of the VLBI group delays. We have developed a weighting scheme to re-weight the observations by parameterizing the source structure component in terms of closure delays and jet orientation relative to the observing baseline. It was implemented in the Vienna VLBI Software. To assess the performance of the extended stochastic model, we analysed the CONT17 legacy sessions and generated suitable reference solutions for comparison. The effects of re-weighting were evaluated with respect to the session fit statistics, source-wise residuals, and geodetic parameters. We find that this relatively simple noise model consistently improves the session fit by about 5% with moderate variation from session to session. The geodetic estimates are not affected to a significant level by this new weighting method. Source-wise we see improved post-fit residuals for 63 out of a total of 91 sources observed.

Description: Radio telescopes with dual linearly polarized feeds regularly participate in Very Long Baseline Interferometry. One example is the VLBI Global Observing System (VGOS), which is employed for high-precision geodesy and astrometry. In order to achieve the maximum signal-to-noise ratio, the visibilities of all four polarization products are combined to Stokes I before fringe-fitting. Our aim is to improve cross-polarization bandpass calibration, which is an essential processing step in this context. Here we investigate the shapes of these station-specific quantities as a function of frequency and time. We observed the extra-galactic source 4C 39.25 for 6 hours with a VGOS network. We correlated the data with the DiFX software and analyzed the visibilities with PolConvert to determine the complex cross-bandpasses with high accuracy. Their frequency-dependent shape is to first order characterized by a group delay between the two orthogonal polarizations, in the order of several hundred picoseconds. We find that this group delay shows systematic variability in the range of a few picoseconds, but can remain stable within this range for several years, as evident from earlier sessions. On top of the linear phase-frequency relationship there are systematic deviations of several tens of degrees, which in addition are subject to smooth temporal evolution. The antenna cross-bandpasses are variable on time scales of ∼1 hr, which defines the frequency of necessary calibrator scans. The source 4C 39.25 is confirmed as an excellent cross-bandpass calibrator. Dedicated surveys are highly encouraged to search for more calibrators of similar quality.

Description: Integer Ambiguity Resolution (IAR) can significantly improve the accuracy of GNSS Precise Orbit Determination (POD). Traditionally, the IAR in POD is achieved at the Double Differenced (DD) level. In this contribution, we develop an Un-Differenced (UD) IAR method for Global Positioning System (GPS)+ BeiDou Navigation Satellite System (BDS) + Galileo navigation satellite system (Galileo)+ Global'naya Navigatsionnaya Sputnikovaya Sistema (GLONASS) quad-system POD by calibrating UD ambiguities in the raw carrier phase and generating the so-called carrier range. Based on this method, we generate the UD ambiguity-fixed orbit and clock products for the Wuhan Innovation Application Center (IAC) of the International GNSS Monitoring and Assessment System (iGMAS). One-year observations in 2020 from 150 stations are employed to investigate performance of orbit and clock products. Notably, the UD Ambiguity Resolution (AR) yields more resolved integer ambiguities than the traditional DD AR, scaling up to 9%, attributable to its avoidance of station baseline formation. Benefiting from the removal of ambiguity parameters, the computational efficiency of parameter estimation undergoes a substantial 70% improvement. Compared with the float solution, the orbit consistencies of UD AR solution achieve the accuracy of 1.9, 5.2, 2.8, 2.1, and 2.7 cm for GPS, BeiDou-2 Navigation Satellite System (BDS-2), BeiDou-3 Navigation Satellite System (BDS-3), Galileo, and GLONASS satellites respectively, reflecting enhancements of 40%, 24%, 54%, 34%, and 42%. Moreover, the standard deviations of Satellite Laser Ranging (SLR) residuals are spanning 2.5–3.5 cm, underscoring a comparable accuracy to the DD AR solution, with discrepancies below 5%. A notable advantage of UD AR lies in its capability to produce the Integer Recovered Clock (IRC), facilitating Precise Point Positioning (PPP) AR without requiring additional Uncalibrated Phase Delay (UPD) products. To assess the performance of quad-system kinematic PPP based on IRC, a network comprising 120 stations is utilized. In comparison to the float solution, the IRC-based PPP AR accelerates convergence time by 31% and enhance positioning accuracy in the east component by 54%.

Description: Open data, as an essential element in the sustainable development of the digital economy, is highly valued by many relevant sectors in the implementation process. However, most studies suppose that there are only data providers and users in the open data process and ignore the existence of data regulators. In order to establish long-term green supply relationships between multistakeholders, we hereby introduce data regulators and propose an evolutionary game model to observe the cooperation tendency of multistakeholders (data providers, users, and regulators). The newly proposed game model enables us to intensively study the trading behavior which can be realized as strategies and payoff functions of the data providers, users, and regulators. Besides, a replicator dynamic system is built to study evolutionary stable strategies of multistakeholders. In simulations, we investigate the evolution of the cooperation ratio as time progresses under different parameters, which is proved to be in agreement with our theoretical analysis. Furthermore, we explore the influence of the cost of data users to acquire data, the value of open data, the reward (penalty) from the regulators, and the data mining capability of data users to group strategies and uncover some regular patterns. Some meaningful results are also obtained through simulations, which can guide stakeholders to make better decisions in the future.

Description: The article evidences to what extent rights-based climate litigation is applied as a strategy to enhance the recognition and protection of climate-induced migrants. Adopting a deduc- tive approach and desk review, the study, illustrates how climate-induced migration has been addressed by International Human Rights Law, with some attention also paid to the growing application of the right to a safe climate and climate justice. The study highlights the duties of both States and private actors in tackling the emerging climate crisis under the human rights agenda. Relevant responsibilities are framed in particular within the scope of rights-based litiga- tion dealing with the topic. We present an analysis of litigation linked to climate-induced migration that was filed before distinct international, regional, and national jurisdictions and, in doing so, propose a chronology of cases—structured in three generations—of how population movements as a result of climate change have been discussed by judicial means. The first generation relates to cases that consider the issue from the perspective of protection—in both national, regional, and international jurisdictions. The second generation emerges within general climate litigation claims, involving commitments linked to the climate agenda. In addition to raising (forced) pop- ulation movements as one of the expected impacts of climate change, such cases frequently call upon a rights-based approach. The third generation encompasses rights-based cases cen- tred on climate-induced migrants per se. The strengths and limitations of rights-based litigation to respond to the topic are finally highlighted: we conclude that litigation remains a blunt but not unpromising tool to respond to climate-induced migration. Generic references to the risk of (forced) population movements largely prevail; nevertheless, strategic rights-based litigation can facilitate the visibility of climate-induced migrants to the international community, fostering the development of legal solutions in the longer term.

Description: The complex phase interactions of the two-phase flow are a key factor in understanding the flow pattern evolutional mechanisms, yet these complex flow behaviors have not been well understood. In this paper, we employ a series of gas–liquid two-phase flow multivariate fluctuation signals as observations and propose a novel interconnected ordinal pattern network to investigate the spatial coupling behaviors of the gas–liquid two-phase flow patterns. In addition, we use two network indices, which are the global subnetwork mutual information (⁠ ⁠) and the global subnetwork clustering coefficient (⁠ ⁠), to quantitatively measure the spatial coupling strength of different gas–liquid flow patterns. The gas–liquid two-phase flow pattern evolutionary behaviors are further characterized by calculating the two proposed coupling indices under different flow conditions. The proposed interconnected ordinal pattern network provides a novel tool for a deeper understanding of the evolutional mechanisms of the multi-phase flow system, and it can also be used to investigate the coupling behaviors of other complex systems with multiple observations.