Lonar Lake, India: An Impact Crater in Basalt

Abstract

Discovery of shock-metamorphosed material establishes the impact origin of Lonar Crater. Coarse breccia with shatter coning and microbreccia with moderately shocked fragments containing maskelynite were found in drill holes through the crater floor. Trenches on the rim yield strongly shocked fragments in which plagioclase has melted and vesiculated, and bombs and spherules of homogeneous rock melt. As the only known terrestrial impact crater in basalt, Lonar Crater provides unique opportunities for comparison with lunar craters. In particular, microbreccias and glass spherules from Lonar Crater have close analogs among the Apollo specimens.

Active methylotrophs in the sediments of Lonar Lake, a saline and alkaline ecosystem formed by meteor impact

“…Being the only well-preserved terrestrial crater to be formed entirely on basalt, it provides an excellent analogue for studying basaltic impact crater structures that are common on the surfaces of other terrestrial planets such as Mars (Hagerty and Newsom, 2003) and the Moon (Fudali et al, 1980). The crater has an average rim diameter of 1830 m and a rim-to-floor depth of about 150 m (apparent depth) (Fredriksson et al, 1973). A saline (NaCl B0.9%) and alkaline lake (pH B10) occupies most of the crater floor .…”

“…Lonar crater (centred at 19159 0 N and 76131 0 E) is a simple, bowl-shaped, near-circular crater formed by meteor impact (Fredriksson et al, 1973) around 52 000 years ago (Sengupta et al, 1997) in the Deccan volcanic flood basalts in Maharashtra, India. Being the only well-preserved terrestrial crater to be formed entirely on basalt, it provides an excellent analogue for studying basaltic impact crater structures that are common on the surfaces of other terrestrial planets such as Mars (Hagerty and Newsom, 2003) and the Moon (Fudali et al, 1980).…”

Temporal bacterial diversity and detection of putative methanotrophs in surface mats of Lonar crater lake

“…The Lonar Lake is a saline and hyperalkaline ecosystem formed entirely on basalt rock by meteor impact [5]. The crater located in India ~550 km east of Mumbai and Arabian Sea, is 150 m deep and 1830 m across [5].…”

40Ar/39Ar impact ages and time–temperature argon diffusion history of the Bunburra Rockhole anomalous basaltic achondrite

“…Interestingly, Lonar is a very small crater of ca. 2 km in diameter (Fredriksson et al, 1973). This means that, as long as the basalt liquidus is reached, the K/Ar system of a basaltic target rock can be reset regardless the size of the crater, although admittedly, local conditions of the melt sheet are likely to play a role as well in this process.…”