Dedication of Large Meteorite Impacts and Planetary Evolution VI to Álvaro Penteado Crósta

ABSTRACT This paper does not have an abstract. Originally, Álvaro Penteado Crósta (born on 7 August 1954) intended to be one of the volume editors of this GSA Special Paper. He was also looking forward to participating in the Large Meteorite Impacts and Planetary Evolution VI conference in October 2019, for which he had long served on the organizing committee. Unfortunately, a long and serious illness derailed both these plans. Therefore, we are instead honoring our dear friend and valued colleague, Álvaro Crósta, for his longstanding and successful impact cratering work, as the mainstay of impact cratering studies in Brazil and indeed in South America, by dedicating this Special Paper to him. Álvaro Crósta has been a Full Professor (Professor Titular) of Geoscience in the fields of remote sensing, mineral exploration, and planetary geology at the Instituto de Geociências of the Universidade Estadual de Campinas (UNICAMP) in Brazil. He has had a highly distinguished academic career, culminating in his tenure (2012–2017) as vice-rector of his university. In 2017, Álvaro was inducted as a Full Member (Membro Titular) into the Academia Brasileira de Ciências...

A View to Anorthosites

It seems anorthosites are by far interested by geologists because they give us great information about Earth history and how it was evolved in planetary geology. Planetary geology is subject the geology of the celestial bodies such as the planets and their moons, asteroids, comets, and meteorites. It is nearly abundant in the moon. So, it seems studying of these rocks give us good information about planetary evolution and the own early time conditions. Anorthosites can be divided into few types on earth such as: Archean-age (between 4,000 to 2,500 million years ago) anorthosites, Proterozoic (2.5 billion years ago) anorthosite (also known as massif or massif-type anorthosite) – the most abundant type of anorthosite on Earth, Anorthosite xenoliths in other rocks (often granites, kimberlites, or basalts). Furthermore, Lunar anorthosites constitute the light-colored areas of the Moon’s surface and have been the subject of much research. According to the Giant-impact hypothesis the moon and earth were both originated from ejecta of a collision between the proto-Earth and a Mars-sized planetesimal, approximately 4.5 billion years ago. The geology of the Moon (lunar science) is different from Earth. The Moon has a lower gravity and it got cooled faster due to its small size. Also, it has no plate tectonics and due to lack of a true atmosphere it has no erosion and weathering alike the earth. However, Eric A.K. Middlemost believed the astrogeology will help petrologist to make better petrogenic models to understand the magma changing process despite some terms geological differences among the Earth and other extraterrestrial bodies like the Moon. So, it seems that these future studies will clarify new facts about planet formation in planetary and earth, too.

Sulfur Ice Astrochemistry: A Review of Laboratory Studies

Sulfur is the tenth most abundant element in the universe and is known to play a significant role in biological systems. Accordingly, in recent years there has been increased interest in the role of sulfur in astrochemical reactions and planetary geology and geochemistry. Among the many avenues of research currently being explored is the laboratory processing of astrophysical ice analogues. Such research involves the synthesis of an ice of specific morphology and chemical composition at temperatures and pressures relevant to a selected astrophysical setting (such as the interstellar medium or the surfaces of icy moons). Subsequent processing of the ice under conditions that simulate the selected astrophysical setting commonly involves radiolysis, photolysis, thermal processing, neutral-neutral fragment chemistry, or any combination of these, and has been the subject of several studies. The in-situ changes in ice morphology and chemistry occurring during such processing are often monitored via spectroscopic or spectrometric techniques. In this paper, we have reviewed the results of laboratory investigations concerned with sulfur chemistry in several astrophysical ice analogues. Specifically, we review (i) the spectroscopy of sulfur-containing astrochemical molecules in the condensed phase, (ii) atom and radical addition reactions, (iii) the thermal processing of sulfur-bearing ices, (iv) photochemical experiments, (v) the non-reactive charged particle radiolysis of sulfur-bearing ices, and (vi) sulfur ion bombardment of and implantation in ice analogues. Potential future studies in the field of solid phase sulfur astrochemistry are also discussed in the context of forthcoming space missions, such as the NASA James Webb Space Telescope and the ESA Jupiter Icy Moons Explorer mission.

Impact shock origin of diamonds in ureilite meteorites

The origin of diamonds in ureilite meteorites is a timely topic in planetary geology as recent studies have proposed their formation at static pressures >20 GPa in a large planetary body, like diamonds formed deep within Earth’s mantle. We investigated fragments of three diamond-bearing ureilites (two from the Almahata Sitta polymict ureilite and one from the NWA 7983 main group ureilite). In NWA 7983 we found an intimate association of large monocrystalline diamonds (up to at least 100 µm), nanodiamonds, nanographite, and nanometric grains of metallic iron, cohenite, troilite, and likely schreibersite. The diamonds show a striking texture pseudomorphing inferred original graphite laths. The silicates in NWA 7983 record a high degree of shock metamorphism. The coexistence of large monocrystalline diamonds and nanodiamonds in a highly shocked ureilite can be explained by catalyzed transformation from graphite during an impact shock event characterized by peak pressures possibly as low as 15 GPa for relatively long duration (on the order of 4 to 5 s). The formation of “large” (as opposed to nano) diamond crystals could have been enhanced by the catalytic effect of metallic Fe-Ni-C liquid coexisting with graphite during this shock event. We found no evidence that formation of micrometer(s)-sized diamonds or associated Fe-S-P phases in ureilites require high static pressures and long growth times, which makes it unlikely that any of the diamonds in ureilites formed in bodies as large as Mars or Mercury.

A Dictionary of Geology and Earth Sciences

‘can really claim to offer comprehensive coverage of the earth sciences’ TES Over 10,000 entries This leading dictionary covers all areas of geoscience, including planetary science, oceanography, palaeontology, mineralogy, and volcanology. In this edition, 675 new entries have been added and include expanded coverage of planetary geology and Earth-observing satellites. The entries are complemented by more than 130 diagrams and numerous web links, while appendices supplement the A–Z and have been extended to include three new tables on the Torino Impact Hazard Scale, Avalanche Classes, and the Volcanic Explosivity Index. It is an essential, authoritative, and jargon-free resource for students of geology, geography, geosciences, physical science, and related disciplines.