![]() ![]() Geophysical techniques based on radioactivity measurements are not generally used for exploration of asteroid impact craters. Although the crater is located on.the drainage divide of two moderate-sized rivers, namely Purna and Penganga there is no evidence to suggest that the impact has resulted in the disruption, truncation or reorganization of the drainage network locally or regionally. The evidence of it being of the impact origin is available in the form of its relatively unaltered morphology, identification of the subsurface breccias beneath the sediments in the crater, presence of shocked minerals, glasses and ejected melt breccias. It has nearly 150 m depth and a rim that is raised nearly 20 m above the surrounding country. With its average diameter of 1.8 km, the crater is a simple, bowl-shaped and remarkably circular depression within a flat country dotted with sporadic conical hills. ![]() The Lonar Ctatet, created by an impact of a bolide or a meteor about 570 thousand years ago in central part of the Deccan Volcanic Province, is one of the very few hypervelocity impact craters in the worid carved out from the basaltic target rocks and the only crater in lava flow sequence of a Continental Flood Basalt Province. We also find no evidence of shock demagnetization or the presence of intense impact-induced or impact-amplified transient magnetic fields that have been proposed around larger impact structures. At Lonar, viscous (and/or chemical) remanent magnetization acquired in the < 50 kyr subsequent to crater formation has obscured any evidence of shock remanent magnetization. We show that paleomagnetism can provide a constraint on shock heating in the absence of petrographic evidence of shock (in this case, < 187 ± 15 ☌). We observed only subtle effects from the impact on the rock-magnetic properties of Lonar materials, which include a slightly elevated coercivity in shocked ejecta blocks. In other areas, substantial vertical axis rotation may have occurred where tear zones developed during folding. In some areas, the recumbent rim fold is preserved and can be approximated as a horizontal cylindrical fold. We constrained the timing of magnetization acquisition at Lonar using a combination of conglomerate tests on ejecta deposit clasts and fold tests on the overturned and jumbled rim fold. The magnetization in the Lonar basalts consists of an original 65 Ma Deccan magnetization and a recent overprint. We investigated the paleomagnetic and rock-magnetic properties of the 1.88 km diameter crater in order to understand the effect of impacts on magnetization in target rocks. ![]() Lonar crater, India, is the best preserved terrestrial impact crater formed in basalt and is a unique terrestrial analogue for small, simple craters on terrestrial planets and the Moon. ![]()
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