¹Sam Uthup, ¹J. Gregory Shellnutt
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2026.116985]

¹Department of Earth Science, National Taiwan Normal University, 88 Tingzhou Road Section 4, Taipei 11677, Taiwan
Copyright Elsevier

Venus is a telluric planet with similar size, composition, and mass to that of the Earth. The Venusian crust is mainly divided into lowland (~80%) and highland regions (~10%) based on their surface elevation. The lowland regions are characterized by featureless lava plains, whereas the highlands consist of crustal plateaux, tesserae terrane, and volcanic troughs. The presence of evolved silicic igneous rocks in the highland regions of the Venus has been debated. In this study, phase equilibria modelling using THERMOCALC and the basaltic compositions obtained from the Venera 14 and Vega 2 lander missions are employed to estimate partial melt compositions in both hydrous and anhydrous conditions. Hydrous partial melting of the Venera 14 composition generated tonalitic-trondhjemite-granodiorite- (TTG) melts at shallow crustal depths with 5% partial melting. The Vega 2 composition could also generate TTG like melts in hydrous conditions, but at a slightly higher-pressure (~5 kbar). However, anhydrous partial melting modelling results were unable to generate a TTG-like melts. The results of THERMOCALC modelling indicate that TTG-like melts can be generated in the crust from the basaltic compositions of Venera 14 and Vega 2 by hydrous partial melting. The implication is that the highland regions of Venus may be an ideal location to search for silicic rocks that are typical of terrestrial Archean crust.

¹Ashley Rogers,^1,2Lucy Forman,³Kai Rankenburg,^1,4Rachel Kirby,³Martin Danišík,¹Victoria Cousins,^1,2,5Gretchen K. Benedix
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70101]
¹Space Science and Technology Centre, School of Earth and Planetary Science, Curtin University, Perth, Western Australia,Australia
²Department of Minerals & Meteorites, Western Australian Museum, Perth, Western Australia, Australia
³John de Laeter Centre, Curtin University, Perth, Western Australia, Australia
⁴School of Earth, Atmosphere and Environment, Monash University, Melbourne, Victoria, Australia
⁵Planetary Science Institute, Tucson, Arizona, USA
Published by arrangement with John Wiley & Sons

Under the current classification scheme, ungrouped irons make up ~11% of all recognized iron meteorites. A further ~7% of iron meteorites are currently classified as simply “irons” and are yet to be fully classified. To potentially classify these meteorites, newer approaches, including either statistical modeling or advanced geochemical/petrological characterization, may be required. To approach this issue, we studied three ungrouped iron meteorites from Western Australia—Pennyweight, Prospector Pool, and Redfields. We conducted petrographical and geochemical analyses using a TESCAN Integrated Mineral Analyzer (TIMA), electron backscattered diffraction (EBSD), and laser ablation inductively coupled mass spectrometry (LA-ICP-MS). Through these analyses, the modal abundances, orientation relationships, and geochemical properties of the key metallic phases were determined. From this work, we have found that spot analyses of the kamacite and plessite are sufficient for iron meteorite classification, and these values can be used to reconstruct a “bulk” geochemical composition. Additionally, statistical data reduction (principal component analysis and t-distributed stochastic neighbor embedding) models have been used, in conjunction with the traditional logarithmic element plots, to assist with classification. Our results agree with previous studies that recommend the reclassification of Prospector Pool to the IIE group. Pennyweight may be a mesosiderite metal nodule with a metal composition closer to the IIIAB and IIE meteorites but has petrographical features similar to the IIE irons. It should remain ungrouped at this stage. Redfields is most likely a member of the IAB complex, potentially an IAB anomalous meteorite. Finally, the statistical models show a dichotomy between the IAB group and that the current iron meteorite groups seem to have more geochemical similarities than differences. Further analysis is required to assess the validity of the current classification scheme.