The origin and evolution of V-rich, magnetite dominated Fe-Ti oxide mineralization; Northwest River Anorthosite, South-Central Labrador, Canada

The Northwest River Anorthosite (NWRA) is a ca. 1625 Ma Paleoproterozoic massif anorthosite located in the Grenville Province of south-central Labrador. Abundant zones of coarse-grained massive to semi-massive Fe-Ti oxide mineralization and disseminated oxide mineralization, which occur in sharp irregular contact with the host anorthosite are present in the NWRA. The Fe-Ti oxide minerals in the NWRA are dominated by magnetite with less abundant ilmenite and pleonaste; all oxide minerals contain abundant and complex exsolution features. Whole-rock geochemistry, petrography and in situ analyses show that regardless of field texture, oxide mineralization is similar in all of the samples analyzed. Whole-rock analyses of massive to semi-massive Fe-Ti oxide mineralization in the NWRA show values of ~10 wt. % TiO₂ and 2700 ppm V (0.48 wt. % V₂O₅). In-situ magnetite analyses contain <0.5 wt. % TiO₂ and 0.6-0.7 wt. % V₂O₅. Composite ilmenite contains ~1 wt. % Mg, 5-7 mol% hematite component and negligible Cr and Al content. Based on oxide mineral chemistry, oxide-anorthosite field relationships, and whole-rock geochemistry, it can be inferred that the formation of the oxide mineralization occurred in a three step process: 1) late-stage magmatic crystallization of impure magnetite; 2) concentration by solid-state remobilization and/or crystal sorting; and 3) reequilibration during subsequent post-emplacement cooling and subsequent Grenvillian metamorphism. These subsolidus processes significantly modified the primary magmatic composition of the oxide minerals through exsolution and reequilibration

A large topographic feature on the surface of the trans-Neptunian object (307261) 2002 MS4_4 measured from stellar occultations

This work aims at constraining the size, shape, and geometric albedo of the dwarf planet candidate 2002 MS4 through the analysis of nine stellar occultation events. Using multichord detection, we also studied the object's topography by analyzing the obtained limb and the residuals between observed chords and the best-fitted ellipse. We predicted and organized the observational campaigns of nine stellar occultations by 2002 MS4 between 2019 and 2022, resulting in two single-chord events, four double-chord detections, and three events with three to up to sixty-one positive chords. Using 13 selected chords from the 8 August 2020 event, we determined the global elliptical limb of 2002 MS4. The best-fitted ellipse, combined with the object's rotational information from the literature, constrains the object's size, shape, and albedo. Additionally, we developed a new method to characterize topography features on the object's limb. The global limb has a semi-major axis of 412 $\pm$ 10 km, a semi-minor axis of 385 $\pm$ 17 km, and the position angle of the minor axis is 121 $^\circ$ $\pm$ 16$^\circ$. From this instantaneous limb, we obtained 2002 MS4's geometric albedo and the projected area-equivalent diameter. Significant deviations from the fitted ellipse in the northernmost limb are detected from multiple sites highlighting three distinct topographic features: one 11 km depth depression followed by a 25$^{+4}_{-5}$ km height elevation next to a crater-like depression with an extension of 322 $\pm$ 39 km and 45.1 $\pm$ 1.5 km deep. Our results present an object that is $\approx$138 km smaller in diameter than derived from thermal data, possibly indicating the presence of a so-far unknown satellite. However, within the error bars, the geometric albedo in the V-band agrees with the results published in the literature, even with the radiometric-derived albedo

Dust Environment Model of the Interstellar Comet 2I/Borisov

2I/Borisov is the first interstellar comet discovered on 2019 August 30, and it soon showed a coma and a dust tail. This study reports the results of images obtained at the Telescopio Nazionale Galileo telescope, on La Palma - Canary Islands, in 2019 November and December. The images have been obtained with the R filter in order to apply our dust tail model. The model has been applied to the comet 67P/Churyumov-Gerasimenko and compared to the Rosetta dust measurements showing a very good agreement. It has been applied to the comet 2I/Borisov, using almost the same parameters, obtaining a dust environment similar to that of 67P/Churyumov-Gerasimenko, suggesting that the activity may be very similar. The dust tail analysis provided a dust-loss rate Qd ≍ 35 kg s-1 in 2019 November and Qd ≍ 30 kg s-1 in 2019 December

Efeitos do Fornecimento de Mistura Mineral Completa e Ureia sobre o Aproveitamento de Feno de Grama-Bermuda (Cynodon Dactylon L. Pers) CV 'Coast Cross 1'.

Foram utilizados 24 carneiros, castrados, em ensaio de digestibilidade e balanco de N, realizado no Departamento de Criacao de Ruminantes e Alimentacao Animal, da Faculdade de Medicina Veterinaria e Zootecnia da USP, no Campus de Pirassununga. O objetivo do trabalho foi verificar os possiveis efeitos da adicao de ureia na mistura mineral, sobre a utilizacao dos nutrientes de feno de grama-bermuda. Os animais foram distribuidos em quatro tratamentos, obedecendo um esquema fatorial, com dois tipos de feno de grama-bermuda, suplementos ou não com ureia incorporada na mistura mineral completa. Os coeficientes medios de digestibilidade foram, para o grupo testemunha e para o grupo tratado, respectivamente, os seguintes: materia seca, 49,8 e 47,8%; proteina, 57,6 e 63,7%; extrato etereo, 36,2 e 33,9%; fibra bruta, 55,7 e 51,9%; extrativos nao-nitrogenados, 53,0 e 47,3%. O testemunha apresentou balanco nitrogenado negativo de -21,3 g, e o tratado, de -26,3 g. Os carneiros que nao receberam uréia, durante o periodo de 35 dias, perderam, por dia, 49,8 g de peso vivo, enquanto os que foram tratados com ureia incorporada ao sal mineral perderam apenas 1,1 g/dia