Abstract With several upcoming sample return missions, such as the Mars Sample Return Campaign, non‐destructive methods will be key to maximizing their scientific output. In this study, we demonstrate that the combination of neutron and X‐ray tomography provides an important tool for the characterization of such valuable samples. These methods allow quantitative analyses of internal sample features and also provide a guide for further destructive analyses with little to no sample treatment, which maintains sample integrity, including minimizing the risk of potential contamination. Here, we present and review the results from four case studies of terrestrial impactites and meteorites along with their analytical setup. Using combined X‐ray and neutron tomography, a Ni‐Fe silicide spherule, that is, projectile material, was located within a Libyan Desert Glass sample and the distribution of hydrous phases was pinpointed in selected impactite samples from the Chicxulub IODP‐ICDP Expedition 364 drill core and the Luizi impact structure, as well as in the Miller Range 03346 Martian meteorite.
Abstract Shocked zircon from impactites from the Mien impact structure, Sweden, has been investigated with the aim to date the impact event and correlate the degree of U–Pb age resetting with shock‐related microtextures. In situ U–Pb spot isotope analyses of granular and microporous–granular zircon grains from the impact melt rocks give an age of 120.0 ± 1.0 Ma. This essentially confirms the previous best estimate age of 122.4 ± 2.3 Ma, while also increasing precision on the Mien impact age. U–Pb isotope mapping shows that radiation damage likely explains the similar U–Pb age reset associated with different shock‐related microtextures. Microporous and some of the granular and microporous–granular domains yield higher U concentrations along with younger 238 U/ 206 Pb dates. Lower U contents with older 238 U/ 206 Pb dates are predominately observed in pristine domains. Due to the U‐decay, the zircon lattice is damaged, a process through which Pb can be lost. This would result in younger 238 U/ 206 Pb dates, as observed for the high U domains. As the zircon crystal lattices were locally weakened, metamictization possibly facilitated the development of microporous and granular textures during the impact event. Analyses of unshocked Mien zircon confirm that radiation damage already existed before impact. Lead loss from granular domains occurred through recrystallization and from microporous domains through Pb leaching by hydrothermal fluids. In addition, our study demonstrates the utility of combined U–Pb isotope mapping and spot analysis in unraveling the link between U–Pb resetting and shock‐related microtextures, the formation of which was in this case likely promoted by pre‐existing radiation damage.
The Luskin Conference Center hosts a full-service hotel in which 200 rooms have been reserved at a reduced rate.All events will be within easy walking distance of Luskin, so there is no need to have a rental car for the week.Of course, there are many other lodging options in LA, with several near the UCLA campus (suggestions will be provided on the website).We are also seeking the possibility of dormitory accommodations for students or those on a tighter budget.Currently, there are no public health restrictions on gatherings in Los Angeles.We are planning for a mostly in-person meeting, with the possibility of remote participation via live on-line and in-schedule talks.Poster presentations will be in-person only.Transportation to UCLA from LA's main international airport (LAX) is straightforward.Los Angeles is a dynamic, multi-cultural city with myriad entertainment possibilities.Although hot spells are possible, the weather in mid-August is likely better than what you'll be leaving at home.The mountains, beaches, and wineries of southern and central California are readily accessed with a rental car for pre-or post-conference fun.We encourage you to reserve the dates of August 13-18 on your calendar today, and we look forward to welcoming you to Los Angeles in the summer of 2023!
Nakhlite meteorites are igneous rocks from Mars that were aqueously altered ~630 million years ago. Hydrothermal systems on Earth are known to provide microhabitats; knowledge of the extent and duration of these systems is crucial to establish whether they could sustain life elsewhere in the Solar System. Here, we explore the three-dimensional distribution of hydrous phases within the Miller Range 03346 nakhlite meteorite using nondestructive neutron and x-ray tomography to determine whether alteration is interconnected and pervasive. The results reveal discrete clusters of hydrous phases within and surrounding olivine grains, with limited interconnectivity between clusters. This implies that the fluid was localized and originated from the melting of local subsurface ice following an impact event. Consequently, the duration of the hydrous alteration was likely short, meaning that the martian crust sampled by the nakhlites could not have provided habitable environments that could harbor any life on Mars during the Amazonian.
Abstract Recognition of impact‐induced deformation of minerals is crucial for the identification and confirmation of impact structures as well as for the understanding of shock wave behavior and crater formation. Shock deformed mineral grains from impact structures can also serve as important geochronometers, precisely dating the impact event. We investigated zircon grains from the Mien impact structure in southern Sweden with the aim of characterizing shock deformation. The grains were found in two samples of impact melt rock with varying clast content, and in one sample of suevitic breccia. We report the first documentation of so‐called “FRIGN zircon” (former reidite in granular neoblastic zircon) from Mien (pre‐erosion diameter 9 km), which confirms that this is an important impact signature also in relatively small impact structures. Furthermore, the majority of investigated zircon grains contain other shock‐related microtextures, most notably granular and microporous textures, that occur more frequently in grains found in the impact melt than in the suevitic breccia. Our findings show that zircon grains that are prime candidates for establishing a new and improved age refinement of the Mien impact structure are present in the impact melt.
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