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Found 92 matches
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  1. ... off the Yucatan Peninsula. The Raton Basin on the New Mexico-Colorado border and Brownie Butte in Montana are located ~2000 km and ~3000 km from the crater, respectively. An ejecta layer is found followed by an Ir-rich fireball layer in each section, stratigraphy that is common to sites proximal to ...
  2. ... to the K/T event. Impact scenarios suggest that most vegetation in North America was destroyed by an initial blast of superheated debris from the crater that was followed by months of darkness. A variety of studies have documented a loss of virtually all herbivorous tetrapods, a major extinction of ...
  3. ... research during the past 25 years, however, has produced several caveats: (a) ancient impacts, which may not be evidenced by preserved craters, must be confirmed by strict geological, petrographic, and/or geochemical criteria (i.e., presence of shock metamorphism and/or traces of meteoritic matter) ...
  4. ... and S in soils persists, as seen in alpha-proton X-ray spectrometry data collected from a shallow trench dug by the Spirit rover on sol 140 at Gusev Crater. Naturally occurring members of the MgSO4•nH2O series on Earth are epsomite (MgSO4•7H2O), hexahydrite (MgSO4•6H2O), and kieserite (MgSO4•H2O) but ...
  5. ... , each center would erupt explosively, forming tuff cones composed of pyroclastic flows, surges and debris avalanche deposits in which block craters occur proximally to vents. Centers then issued domes and flows. Four of these occur along a northwest trend and once formed a chain of overlapping domes ...
  6. ... of a great spectrum of unusual carbonate and evaporite-precipitating environments. Lakes Gnotuk, Bullenmerri and Keilambete occupy small, deep craters in the central part of the Volcanic Plains. The lakes are topographically closed, and because of their small drainage basins and limited groundwater ...
  7. ... allows them to gain experience studying various volcanic rocks. To view volcanic rocks, we make stops in the Absaroka Mountains, Yellowstone NP, and Craters of the Moon NM. To view areas with classic geologic structures, we make stops in the Big Horn Mountains, Grand Teton National Park, Gros Ventre ...
  8. ... hot (>200°C) highly saline, metal-rich, hydrocarbon-bearing brines. The source of the hot quartz-forming brines is assumed in the center of the crater structure. Trace hydrocarbon being present in some quartz inclusions may be derived from cracking of pre-impact organic matter. Remobilization of ...
  9. ... a lunar-like planet with hints of terrestrial similarities. The view from MGS is that Mars is neither the Moon with an atmosphere nor the Earth with craters, but a planet with its own unique and strange history. From a distant past when liquid water pooled in depressions on the surface that acted as ...
  10. ... oceanic impacts (~10-km-diameter bolide) penetrate well into the upper mantle (~40-km depth), eject mostly water or water vapor from the transient crater, and generate megatsunami (~4 km initial height) capable of coastal stratigraphic effects on a global scale. Impact-generated megatsunami, consequently ...

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