Geological evidence suggests that these terraces may signal a period of quiescence in Deccan volcanism prior to the Chicxulub impact. Apparently never before noticed, these terraces are part of the western Ghats, a mountain chain named after the Hindu word for steps. More from Earth Sciences.
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Home Earth Earth Sciences. April 30, Illustration of a hot mantle plume "head" pancaked beneath the Indian Plate. The theory by Richards and his colleagues suggests that existing magma within this plume head was mobilized by strong seismic shaking from the Chicxulub asteroid impact, resulting in the largest of the Deccan Traps flood basalt eruptions.
Explore further. Provided by University of California - Berkeley. Citation : Did dinosaur-killing asteroid trigger largest lava flows on Earth? This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Synthesizing nanomaterials from nature's blueprints 8 hours ago.
Can we assume constant C14 to C12 ratio in living tissues? Sep 19, Volcanologists want to put sensors directly into an Underground Magma Chamber Sep 16, Related Stories. New, tighter timeline confirms ancient volcanism aligned with dinosaurs' extinction Dec 18, Dec 12, Feb 04, Study suggests dinosaurs killed off by more than one asteroid Aug 31, Mar 04, Nov 17, This assumes the bright soil at swirls is at least partially the result of the magnetic field blocking full solar wind access to the surface 39 , 40 , 41 , 42 , Hence, swirls will have stronger magnetization than adjacent terrain without swirls.
We use the mapping of Denevi et al. In our modeling, we use a magnetization direction for the anomalies in Supplementary Fig. Briefly, the method assumes that the magnetization is unidirectional and distributed throughout the subsurface.
In this case the problem can be reduced to modeling a sheet of dipoles at the surface of variable strength and equal direction. This inversion applied to the entire region in the white box s in Fig. The results from such a method are too coarse.
Importantly, even extreme uncertainties in the magnetization direction would not affect our estimate of peak magnetizing field strength by a factor of more than two. This produced a total moment of 1. This thickness approximation is motivated by previous work that showed the depth to the top of the source must be smaller than the horizontal length scale of the swirl, if swirls are indeed formed by standoff of the solar wind We note that smaller assumed layer thicknesses would require higher M , and therefore higher even less realistic magnetizing fields for indigenous lunar materials see end of paragraph.
Using the observed surface area of the swirls 6. We then related M to the ambient field via see discussion in Wieczorek et al. In the main text we showed that the magnetic field morphology at Houzeau crater and the unnamed crater to its north are correlated with the crater interior topography Fig. Both of these units comprise parts of the Hevelius Formation. Hood et al.
Although the ejecta in our simulations cover a large area and the variation of ejecta are relatively smooth Fig. Such burial would also be consistent with the lack any reported compositional anomalies associated with magnetic anomalies. A veneer of Orientale ejecta may also help bury the impactor ejecta deposit.
To determine the provenance and spatial distribution of antipodal ejecta we simulate impacts using the iSALE-3D shock physics code 50 , This code uses a solver as described in Hirt et al. Following Melosh et al. Owing to the limitations of the current numerical code, we cannot consider differentiated impactors.
Since our provenance plot indicates that the outer portion of the impactor dominates the antipodal ejecta Supplementary Fig. We also consider the material strength and summarize input material parameters in Supplementary Table 2. Our km-diameter impactor simulations are valid for roughly km-diameter scale basins. Assuming hydrodynamic similarity, the ejecta thicknesses reported here can also be scaled linearly by impactor size 63 see also Supplementary Note 2.
To track ejecta properties, such as position, velocity, and pressure, we place a Lagrangian tracer particle in each computational cell at the beginning of impact simulations. To reach the antipode of the lunar basin, the ejecta velocity should range between the escape velocity of the Moon 2. Lunar magnetic field data are from the model of Tsunakawa et al. The code to determine the magnetization direction is available from the authors upon reasonable request.
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