A Classification Table for Achondrites

Classifying chondrites is relatively easy and the criteria are well documented. It is based on mineral compositions, textural characteristics and more recently, magnetic susceptibility. It can be more difficult to classify achondrites, especially those that are very similar to terrestrial igneous rocks, because mineralogical, textural and compositional properties can be quite variable. Achondrites contain essentially olivine, pyroxenes, plagioclases, oxides, sulphides and accessory minerals. Their origin is attributed to differentiated parents bodies: large asteroids (Vesta); planets (Mars); a satellite (the Moon); and numerous asteroids of unknown size. In most cases, achondrites are not eye witnessed falls and some do not have fusion crust. Because of the mineralogical and magnetic susceptibility similarity with terrestrial igneous rocks for some achondrites, it can be difficult for classifiers to confirm their extra-terrestrial origin. We -as classifiers of meteorites- are confronted with this problem with every suspected achondrite we receive for identification. We are developing a "grid" of classification to provide an easier approach for initial classification. We use simple but reproducible criteria based on mineralogical, petrological and geochemical studies. We presented the classes: acapulcoites, lodranites, winonaites and Martian meteorites (shergottite, chassignites, nakhlites). In this work we are completing the classification table by including the groups: angrites, aubrites, brachinites, ureilites, HED (howardites, eucrites, and diogenites), lunar meteorites, pallasites and mesosiderites. Iron meteorites are not presented in this abstract

LANDSLIDE SUSCEPTIBILITY MAPPING IN THE MUNICIPALITY OF OUDKA, NORTHERN MOROCCO: A COMPARISON BETWEEN LOGISTIC REGRESSION AND ARTIFICIAL NEURAL NETWORKS MODELS

The Rif is among the areas of Morocco most susceptible to landslides, because of the existence of relatively young reliefs marked by a very important dynamics compared to other regions. These landslides are one of the most serious problems on many levels: social, economic and environmental. The increase in the frequency and impact of landslides over the past decade has demonstrated the need for an in-depth study of these phenomena, allowing the identification of areas susceptible to landslides. The main objective of this study is to identify the optimal method for the mapping of the area susceptible to landslides in municipality of Oudka. This area has been marked by the largest landslide in the region, caused by heavy rainfall in 2013. Two Statistical Methods i) Regression Logistics (LR) ii) Artificial Neural Networks (ANN), were used to create a landslide susceptibility map. The realization of this susceptibility map required, first, the mapping of old landslides by the aerial photography, the data of the geological map and by the data obtained using field surveys using GPS. A total of 105 landslides were mapped from these various sources. 50% of this database was used for model building and 50% for validation. Eight independent landslide factors are exploited to detect the most sensitive areas: altitude, slope, aspect, distance of faults, distance streams, distance from roads, lithology and vegetation index (NDVI). The results of the landslide susceptibility analysis were verified using success and prediction rates. The success rate (AUC&thinsp;=&thinsp;0.918) and the prediction rate (AUC&thinsp;=&thinsp;0.901) of the LR model is higher than that of the ANN model (success rate (AUC&thinsp;=&thinsp;0.886) and prediction rate (AUC&thinsp;=&thinsp;0.877). These results indicate that the Regression Logistic (LR) model is the best model for determining landslide susceptibility in the study area.</p

The Benguerir meteorite: Report and description of a new Moroccan fall

A meteorite fall was witnessed on November 22, 2004, at 11:45 A.M. (GMT) near the city of Benguerir, Morocco. This is one of the first falls from Morocco to be scientifically described. The total mass of the fall is estimated to be at least 40 and 80 kg. Three impact locations have been identified, two of them in soft ploughed ground and a third on a granite surface, which was apparently broken by the impact. The weight of complete pieces range between approximately 100 g and 10 kg. We have classified the stone as an LL6 ordinary chondrite, based on mineralogy and petrology, with shock grade S3 and alteration W0. The dark fusion crust is perfectly fresh, and a number of samples were collected shortly after the fall by local residents and authorities before rainfall, which occurred a few days later. We show that the magnetic susceptibility of Benguerir is homogeneously high, indicating a constant metal content despite brecciation, in the high range for LL6. The LL6 classification can also be confirmed magnetically, with a specific signature similar to other measured LL6 falls.The Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Fe-Mn exchange between Daubreelite and Alabandite in E Chondrites. A metamorphic index ?

International audienceAssessing the metamorphic type of enstatite chondrites cannot rest on the Fe-Mg exchange among silicates. Looking for a reliable index we studied the distribution of cations Fe and Mn among the sulphides daubreelite and alabandite

TAMDAKHT METEORITE (MOROCCO): AN IMPORTANT FALL WITH A RARE FUSION CRUST

80th Annual Meeting of the Meteoritical-Society, Santa Fe, NM, JUL 23-28, 2017International audienc

The Puerto Lápice eucrite. Free sample delivery from vesta : trajectory, orbital solutions, and shock history from cathodoluminiscence

A daylight fireball was witnessed all over Spain in the afternoon of May 10, 2007. Several pictures of the fireball’s train taken from different locations in Spain, and eyewitnesses reports allowed the determination of its trajectory and range of orbital solutions. The progenitor meteoroid was in an Apollo-type orbit, with low inclination and perihelion distance just below 1 Astronomical Unit [1]. The meteorite was recovered a few weeks after its fall, and presented to the community in the Meteoroids 2007 conference of Barcelona in June 2007 [2]. A detailed characterization of Puerto Lápice meteorite revealed its eucritic and brecciated nature [3]. Oxygen isotopes also confirmed that it belongs to the HED suite, the main group of basaltic eucrites [3]. The meteorite probably suffered a complex shock history as reveals the presence of abundant shock veins that evidence at least three different shock events

Strewn field, mineralogy, and petrology of Al Haggounia 001: A unique enstatite chondrite

International audienceIn this work, we investigate macroscopic characteristics, magnetic susceptibility, mineralogy, and mineral composition of Al Haggounia 001. The samples were collected during eight field missions in the period between 2015 and 2019. In the strewn field of about 65 km in length, the specimens are found either on the surface or shallowly buried in loose sediments, which rules out the previous suggestions that this meteorite is a fossil meteorite. Macroscopically, the samples exhibit three major lithologies with various colors, porosities, and distributions of oxidized veins. The data obtained using transmitted and reflected light microscopy, scanning electron microscopy, and electron microprobe analysis confirm the macroscopic observations and show a heterogenous distribution of silicates and metal sulfides. Al Haggounia 001 is composed of enstatite, plagioclase, kamacite, taenite, schreibersite, daubreelite, troilite, graphite, sinoite, and silica polymorphs. We identified a new type of chondrules that are flattened and composed of rods of albite and enstatite, as well as elongated nodules of metal and sulfides, in addition to compression fractures in the form of subparallel veinlets. These features presumably reflect the deformation caused by shock. The magnetic susceptibility of Al Haggounia 001 (4.39 ± 0.20) is much lower than that of usual EH (5.48 ± 0.16) and EL (5.46 ± 0.04) chondrites but is in the range of E finds (5.05 ± 0.43). The thermomagnetic and hysteresis measurements are controlled by type, size, distribution of metal‐sulfide nodules, arrangement of oxyhydroxide veins, and weathering. Al Haggounia 001 is an anomalous meteorite with a polymict nature. It records multiple events revealing its unique origin which expends the groups of enstatite chondrites and provides insights into the complex formation and evolution history of their parent body