Lonar crater in India, centered at 19.97°N and 76.50°E is relatively young (few tens of thousands years) and, thus, well preserved meteorite impact structure. This 1.88-km-diameter simple structure has been formed into the 66 Ma old Deccan traps. As the target of Lonar is magnetically homogeneous, it is a perfect site to study the effect of relatively small impact event into the magnetic properties of rocks, and the magnetic field. In October 2017, has been performed ground magnetic mapping of Lonar with help of two proton precession magnetometers. The mapping was done in a squared area of about 36 km2 (6´6 km) including the crater depression, rims, and surrounding terrain. Magnetic map (not corrected for latitude) reveals a circular negative anomaly more than 1000 nT in amplitude, which corresponds to the crater depression. The negative anomaly is surrounded by semicircular feature of up to 500 nT positive anomalies that correlate with present rim of the crater. The total diameter of the Lonar magnetic anomalies is about 2.25 km, which is just 20% more compared to the crater rim-to-rim diameter.
It is considered that The Morasko meteorite shower happened about 5400 years BP with a trajectory from NE to SW (Bronikowska et al. 2015). Recent studies not only prove that this fall could be observed in Februrary 14, 1271, but also that location of most findings in the area to the east side of the craters, should not be taken as the main indicator of impact direction. The proper answer can be given base on knowledge related to oblique impacts, supported by understanding of complicated fragmentation process. The largest crater in Morasko Meteorite Restricted Area has main ejecta plume located in SE, side walls in SW and NE, and free of ejecta Zone of Avoidance (ZoA) in NW. This clearly shows that impact trajectory was approximatelly from NW to SE. There were also discovered other structures, 2 km North from Restricted Area, having common features. Their ejecta plumes as well as few raised ducts (possible traces of underground penetration) are directed to SE, pointing the largest structure – Umultowskie Lake, located approx. 2 km ESE from known main Morasko crater. Shapes of cavities, their walls and ejecta asymmetry allow estimating trajectories and defining new Morasko strewnfield, which matches not only location of impact strucures and discovered meteorite fragments, but also explains smaller (3–4 kg) findings in the neighborhood of Oborniki Wielkopolskie.
It’s considered that one half of all projectiles are striking surface of planets at the angle lower than 45°. Our knowledge of oblique impact events is based on computer modelling, laboratory experiments and observation of craters on the Moon, Mars, Venus and other celestial bodies. Recent discovery in northeast Poland, reveals at least four structures with features reserved for low-angle impacts. In this article we show and explain them using high-quality laser air scanning data (LiDAR) in comparison to results of experiments and similar real known objects on other planets. Also we try to verify by analyzing historical sources if multiple impact event could occur in our area and, if it was noticed and reported in the papers.
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