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Found 92 matches
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  1. ... ATHENA SCIENCE TEAM, the, NASA Jet Propulsion Lab, Pasadena, CA 91109 On January 3 2004, the NASA Spirit rover landed on the plains inside the Gusev Crater in the southern hemisphere of Mars, and has made observations of the landing site and nearby region in visual and infrared wavelengths, as well ...
  2. ... and there is no geochemical for alteration by hydrothermal fluids. The origin of the CRM is enigmatic. It is not clear that the CRM present in the crater is directly related to the impact, as a similar component is found in undeformed limestones outside of the crater. The CRM does appear to be more ...
  3. ... , Reston, VA 20192 In 2004, at Cape Charles, Va., the USGS drilled an 823 m test hole into the east flank of the central uplift within the central crater of the late Eocene Chesapeake Bay impact structure. Cores were recovered from depths of 823-744 m and 433-427 m, and cuttings were collected from the ...
  4. ... -FIRST CENTURY     Stiles, Cynthia A.; Barak, Phillip W.; Nater, Ed STRUCTURAL CHARACTER OF THE TERRACE ZONE AND IMPLICATIONS FOR CRATER FORMATION, CHICXULUB IMPACT CRATER     Gorney, David L.; Gulick, Sean P.S.; Christeson, Gail L. PALEOENVIRONMENTAL ANALYSIS ...
  5. ... shock melting and vaporization, and require simulations with high spatial resolution near the impact point. Late stages investigate the process of crater collapse, modeling the formation of the final impact structure, and require long integration time and a large spatial mesh. Continuous improvement ...
  6. ... megaregolith holding concentrated brines and salts (Knauth and Burt, 2002; Burt and Knauth, 2003). The Opportunity site lies among possible rampart craters and ejecta aprons usually interpreted as the result of impact into wet targets. Owing to evaporation followed by fractional crystallization during ...
  7. ... stratigraphic interval within this unit. The upper volcanic units intercalated within the rocks of Pavits Spring have been identified as part of the Crater Flat Group (13.2 Ma), which erupted from the Silent Canyon Caldera. The Silent Canyon Caldera is located within the Southwest Nevada volcanic field ...
  8. ... 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 ...
  9. ... 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 ...
  10. ... 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) ...

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