^1,2,3,4Damaris Montano,^1,5Marta Gasparrini,^2,3Axel Gerdes,⁵Giovanna Della Porta,^2,3Richard Albert
Earth and Planetary Science Letters 568, 117011 Link to Article [https://doi.org/10.1016/j.epsl.2021.117011]
¹IFP Energies nouvelles, 1-4 avenue de Bois-Préau, 92852, Rueil-Malmaison, France
²Institut für Geowissenschaften, Goethe University Frankfurt, Altenhöferallee 1, 60438 Frankfurt am Main, Germany
³Frankfurt Isotope and Element Research Center (FIERCE), Goethe University Frankfurt, Frankfurt am Main, Germany
⁴Sorbonne Université; ED 398 – GRNE, 4, place Jussieu, 75252 Paris, France
⁵Università degli Studi di Milano; Dipartimento di Scienze della Terra “Ardito Desio”, via Mangiagalli 34, 20133 Milan, Italy
Copyright Elsevier

The Nördlinger Ries Crater lacustrine basin (South-West Germany), formed by a meteorite impact in the Miocene (Langhian; ∼14.9 Ma), offers a well-established geological framework to understand the strengths and limitations of U-Pb LA-ICPMS (in situ Laser Ablation-Inductively Coupled Plasma Mass Spectrometry) geochronology as chronostratigraphic tool for lacustrine (and more broadly continental) carbonates. The post-impact deposits include siliciclastic basinal facies at the lake centre and carbonate facies at the lake margins, coevally deposited in a time window of >1.2 and <2 Ma. Depositional and diagenetic carbonate phases (micrites and calcite cements) were investigated from three marginal carbonate facies (Hainsfarth bioherm, Adlersberg bioherm and Wallerstein mound). Petrography combined with C and O stable isotope analyses indicate that most depositional and early diagenetic carbonates preserved pristine geochemical compositions and thus the U-Pb system should reflect the timing of original precipitation. In total, 22 U-Pb ages were obtained on 10 different carbonate phases from five samples. The reproducibility and accuracy of the U-Pb (LA-ICPMS) method were estimated to be down to 1.5% based on repeated analyses of a secondary standard (speleothem calcite ASH-15d) and propagated to the obtained ages. Micrites from the Hainsfarth, Adlersberg and Wallerstein facies yielded ages of 13.90 ± 0.25, 14.14 ± 0.20 and 14.33 ± 0.27 Ma, respectively, which overlap within uncertainties, and are consistent with the weighted average age of 14.30 ± 0.20 Ma obtained from all the preserved depositional and early diagenetic phases. Data indicate that sedimentation started shortly after the impact and persisted for >1.2 and <2 Ma, in agreement with previous constraints from literature, therefore validating the accuracy of the applied method. Later calcite cements were dated at 13.2 ± 1.1 (), 10.2 ± 2.7 and 9.51 ± 0.77 Ma, implying multiple post-depositional fluid events. This study demonstrates the great potential of the U-Pb method for chronostratigraphy in continental systems, where correlations between time-equivalent lateral facies are often out of reach. In Miocene deposits the method yields a time resolution within the 3rd order depositional sequences (0.5–5 Ma).

¹Robert I. Citron,^2,3Peter Jenniskens,⁴Christopher Watkins,⁵Sravanthi Sinha,⁶Amar Shah,⁷Chedy Raissi,⁸Hadrien Devillepoix,²Jim Albers
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13663]
¹Department of Earth and Planetary Sciences, University of California, Davis, Davis, California, 95616 USA
²SETI Institute, Mountain View, California, 94043 USA
³NASA Ames Research Center, Moffett Field, California, 94035 USA
⁴Scientific Computing, Commonwealth Scientific and Industrial Research Organisation, Clayton, Victoria, 3181 Australia
⁵Holberton School of Software Engineering, San Francisco, California, 94111 USA
⁶Department of Engineering, Computational and Biological Learning, Cambridge University, Cambridge, CB2 1PZ UK
⁷Institut National de Recherche en Informatique et en Automatique, Villers-lès-Nancy, 54506 France
⁸Space Science & Technology Centre, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, Western Australia, 6845 Australia
Published by arrangement with John Wiley & Sons

The recovery of freshly fallen meteorites from tracked and triangulated meteors is critical to determining their source asteroid families. Even though our ability to locate meteorite falls continues to improve, the recovery of meteorites remains a challenge due to large search areas with terrain and vegetation obscuration. To improve the efficiency of meteorite recovery, we have tested the hypothesis that meteorites can be located using machine learning techniques and an autonomous drone. To locate meteorites autonomously, a quadcopter drone first conducts a grid survey acquiring top-down images of the strewn field from a low altitude. The drone-acquired images are then analyzed using a machine learning classifier to identify meteorite candidates for follow-up examination. Here, we describe a proof-of-concept meteorite classifier that deploys off-line a combination of different convolution neural networks to recognize meteorites from images taken by drones in the field. The system was implemented in a conceptual drone setup and tested in the suspected strewn field of a recent meteorite fall near Walker Lake, Nevada.