Geological Origin
Lonar Lake lies within the only known extraterrestrial impact crater found within the great Deccan Traps basaltic formation of India. The lake was initially believed to be of volcanic origin, but now it is recognized as an impact crater created by the hypervelocity impact of either a comet or a meteorite. The presence of plagioclase that has been either converted into maskelynite or contains planar deformation features (PDFs) has confirmed the impact origin of this crater. It is argued that only shock metamorphism caused by hypervelocity impact can transform plagioclase into maskelynite or create PDFs. The presence of shatter cones, impact deformation of basalt layers comprising its rim, shocked breccia inside the crater, and non-volcanic ejecta blanket surrounding the crater are further proof of the impact origin of Lonar crater.
Crater has oval shape. Meteorite impact came from the east, in a tilt of 35 - 40 degrees.
There are various estimates of the age of impact crater. Earlier thermoluminescence analyses gave a result of 52 thousand years, while recent Argon-argon dating testifies that this crater is much older - it could be 570 000 ± 47 000 years old. This greater age is in line with the degree of erosion processes of crater rims.
As a result of the studies, broadly, the geological features of the Lonar crater has been marked under five distinguishable zones, exhibiting distinct geomorphic characteristics.
The five zones are:
- The outermost ejecta blanket
- The crater rim
- The slopes of the crater
- The crater basin, excluding lake
- The crater lake
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