A love letter from outer space: Lonar Lake, India

Around 50,000 years ago, outer space gifted the earth with a crater that formed the foundations of the world’s third largest natural saltwater lake, situated within a flat volcanic area known as the Deccan Plateau. This resulted from a 2 million tonne meteorite tunnelling through the earth’s atmosphere at the velocity of 90,000km/hour and colliding into the Deccan Plateau. As time slipped away, pressure and heat melted the basalt rock tucked underneath the impact, and the accumulation of rainwater filled the crater with water. These foundations curated what is famously known today as the ‘Lonar Lake’.

What is unique about the Lonar Lake is that it is the only meteorite-crater formed in basaltic terrain - synonymous to a lunar terrain. Additionally, the remnants bear similarities to the terrestrial composition of Mercury, which contains craters, basaltic rock and smooth plains resulting from volcanic activity. Many speculations have arisen to prove the theory of the crater forming from the impact of a meteorite. One such collaborative study conducted by The Smithsonian Institute of Washington D.C. USA, the Geological Survey of India and the US Geological Survey involved drilling holes at the bottom of the crater and scrutinising the compositions of rock samples sourced from the mining. When tested in the laboratory, it was found that the rock samples contained leftovers of the basaltic rock that were modified from the crater collision under high heat and pressure. In addition, shattered cone-shaped fractures, due to high velocity shock waves being transmitted into the rocks, were identified. These two observations align with the meteorite impact phenomenon.

Additionally, along with its fascinating astronomical properties, scientists have been intrigued by the chemical composition of the lake within the crater. Its dark green colour results from the presence of the blue-green algae Spirulina. The water also has a pH of 10, making the water alkaline in nature, supporting the development of marine systems. One explanation for the alkalinity of the water is that it is a result of immediate sulphide formation, where the groundwater of meteorite origin contains CO2 undergoes a precipitation reaction with alkaline ions, leaving a carbonate precipitate with an alkaline nature.  What is also striking about the composition of the water as well is its saline nature, which coexists with the alkaline environment - a rare phenomenon to occur in ecological sciences.

The conception of the lake, from the matrimony of Earth with the debris within outer space, has left its imprints within the physical world. It's a love letter, written in basaltic stone and saline water, fostering innovation in ecology. The inscription of the meteorite’s journey within the crater has branched two opposing worlds, one originating millions of miles away from humans with one that resides in the natural grounds of our souls.

Written by Shiksha Teeluck

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REFERENCES

Taiwade, V. S. (1995). A study of Lonar lake—a meteorite-impact crater in basalt rock. Bulletin of the Astronomical Society of India, 23, 105–111.

Tambekar, D. H., Pawar, A. L., & Dudhane, M. N. (2010). Lonar Lake water: Past and present. Nature Environment and Pollution Technology, 9(2), 217–221.