The first large meteorite impact structure discovered in the Middle East: Jebel Waqf as Suwwan,Jordan

Abstract— Triggered by re‐evaluation of a 1960s report on the regional geology of the northeastern border region of Jordan and following Landsat satellite image investigation, a 5.5 km diameter, complex, circular structure was discovered in the central eastern region of the Kingdom of Jordan. Initial ground truthing revealed complex geological structures involving Upper Cretaceous and Paleogene strata, and including a prominent outer rim rising up to 60 m above the surrounding plain, an intermediate ring of up to 20 m elevation within a ring syncline, and a central zone of stratigraphically uplifted sedimentary strata characterized by intense macroscopic (folding and faulting, widespread cataclasis) and locally mesoscopic (cataclasis) deformation. Ten sites with shatter cone development in fine‐grained sandstone or limestone have been mapped to date, mostly in the outer parts of the central uplifted area. This finding confirms that the Jebel Waqf as Suwwan structure was formed as the result of the impact of an extraterrestrial projectile. Search for impact‐diagnostic micro‐deformation has been rather unsuccessful: only 1 quartz grain with both planar deformation features and planar fractures has been detected in a sandstone sample to date. The overall majority of the approximately 70 samples investigated by micropetrographic analysis consist of extremely fine‐grained chert, siltstone, or marly limestone. Cataclasis is widespread in chert and limestone, also on the micro‐scale. Considering the severely limited amount of characteristic impact microdeformation, and the stratigraphic situation within the central uplift, it is likely that a relatively deep level of the central uplift is currently exposed. The extensive drainage demonstrated for this region supports the conclusion that this impact structure could be quite deeply eroded‐especially as its geology involves some relatively soft lithologies (marls, limestones). The age of this impact event is at present poorly constrained at post‐Middle to Lower Eocene.     

Lunar meteorite regolith breccias: An in situ study of impact melt composition using LA‐ICP‐MS with implications for the composition of the lunar crust

Dar al Gani (DaG) 400, Meteorite Hills (MET) 01210, Pecora Escarpment (PCA) 02007, and MacAlpine Hills (MAC) 88104/88105 are lunar regolith breccia meteorites that provide sampling of the lunar surface from regions of the Moon that were not visited by the US Apollo or Soviet Luna sample return missions. They contain a heterogeneous clast population from a range of typical lunar lithologies. DaG 400, PCA 02007, and MAC 88104/88105 are primarily feldspathic in nature, and MET 01210 is composed of mare basalt material mixed with a lesser amount of feldspathic material. Here we present a compositional study of the impact melt and impact melt breccia clast population (i.e., clasts that were generated in impact cratering melting processes) within these meteorites using in situ electron microprobe and LA‐ICP‐MS techniques. Results show that all of the meteorites are dominated by impact lithologies that are relatively ferroan (Mg#_<70), have high Sc/Sm ratios (typically >10), and have low incompatible trace element (ITE) concentrations (i.e., typically <3.2 ppm Sm, <1.5 ppm Th). Feldspathic impact melt in DaG 400, PCA 02007, and MAC 88104/05 are similar in composition to that estimated composition for upper feldspathic lunar crust ( Korotev et al. 2003 ). However, these melt types are more mafic (i.e., less Eu, less Sr, more Sc) than feldspathic impact melts returned by the Apollo 16 mission (e.g., the group 3 and 4 varieties). Mafic impact melt clasts are common in MET 01210 and less common in PCA 02007 and MAC 88104/05. We show that unlike the Apollo mafic impact melt groups ( Jolliff 1998 ), these meteorite impact melts were not formed from melting large amounts of KREEP‐rich (typically >10 ppm Sm), High Magnesium Suite (typically >70 Mg#) or High Alkali Suite (high ITEs, Sc/Sm ratios <2) target rocks. Instead the meteorite mafic melts are more ferroan, KREEP‐poor and Sc‐rich, and represent mixing between feldspathic lithologies and low‐Ti or very low‐Ti (VLT) basalts. As PCA 02007 and MAC 88104/05 were likely sourced from the Outer‐Feldspathic Highlands Terrane our findings suggest that these predominantly feldspathic regions commonly contain a VLT to low‐Ti basalt contribution.     

Venus as a natural laboratory for search of life in high temperature conditions: Events on the planet on March 1, 1982

New classes of extrasolar planets with relatively small masses (“super-Earths”) located in low orbits near low luminosity stars possess moderately high temperature and atmospheric pressure at their surfaces. Such physical conditions and composition of an atmosphere is incompatible with the Earth’s aminonucleic acid form of life. But should they be considered as conditions incompatible with any form of life at all? Considering the conditions on Venus as a possible analogue of physical conditions on low-orbiting exoplanets of the “super-Earths” type, a new analysis of Venusian surface panoramas’ details has been made. These images were produced by the VENERA landers in 1975 and 1982. Also the images which had not been previously considered were included in the processing. A few relatively large objects were found with size ranging from a decimeter to half meter and with unusual morphology. The objects were observed in some images, but were absent in the other or altered their shape. The article presents the obtained results and analyzes the evidence of reality of these objects.     

Detection of ferric iron in an exsolved lunar pyroxene using electron energy loss spectroscopy (EELS): Implications for space weathering and redox conditions on the Moon

To shed light on the mechanism of formation of nanophase iron particles (npFe) in space-weathered materials from airless bodies, we analyzed exsolved and unexsolved space-weathered lunar pyroxenes from Apollo 17 sample 71501. The exsolved pyroxene allowed for the observation of the effects of space weathering on similar mineral phases with variable composition. Using coordinated scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy (EELS), we determined that two coexisting pyroxenes in the exsolved grain showed systematic variations in response to space weathering, despite equivalent exposure conditions. The npFe in the space-weathered rim of augite lamellae were smaller and fewer than the npFe in the rim of pigeonite lamellae. EELS spectrum imaging revealed the presence and heterogeneous distribution of Fe⁰, Fe²⁺, and Fe³⁺ in the exsolved pyroxene. Metallic iron occurred in the npFe, a mixture of Fe²⁺ and Fe³⁺ occurred in the pigeonite lamellae, and the augite lamellae contained virtually all Fe³⁺. Approximately 50% of the total Fe measured in the exsolved pyroxene grain was ferric. Partitioning of Fe²⁺ and Fe³⁺ among the lamellae is invoked to explain the difference in npFe development in pigeonite and augite. The results of this study, the first to identify Fe³⁺ in a crystalline lunar ferromagnesian silicate, have implications for our understanding of how space weathering might proceed in oxidized phases. Furthermore, the discovery of an Fe³⁺-rich pyroxene also supports attribution of the 0.7 μm absorption feature observed in Galileo Solid State Imager data to oxidized Fe in clinopyroxenes.