crops of parautocthonous megabreccia (MBu) in Uzboi Valles ~x km from the rim of Holden crater. PARAUTOCHTHONOUS MEGABRECCIAS AND POSSIBLE EVIDENCE OF IMPACT-INDUCED HYDROTHERMAL ALTERATION IN HOLDEN CRATER, MARS. L. L. Tornabene, G. R. Osinski, and A. S. McEwen, Lunar and Planetary Lab, University of Arizona, 1541 E. University Blvd., Tucson, Arizona, 85721, USA ([email protected], De...

Introduction: Isidis Planitia, a Noachian impact crater infilled with Hesperian aged basalts, is located on Mars on the crustal dichotomy and is antipodal to the Tharsis rise [1]. Measuring 1400 km across and 2 km deep, it is comparable in scale and age to lunar mascons. The basin contains an interesting pattern of both radial and concentric wrinkle ridges (see Figure 1), and massive graben are...

Mathematical analysis demonstrates that substantial impact crater deposits should have been produced during the last 2 Gy of Earth's history. Textures of impact deposits are shown to resemble textures of tillites and diamictites of Precambrian and younger ages. The calculated thickness distribution for impact crater deposits produced during 2 Gy is similar to that of tillites and diamictites <2...

Introduction: Several craters on Mars are partially filled by material emplaced by post-impact processes. Populations of such craters include those in the circum-south polar cap region, in Arabia Terra, associated with the Medusae Fossae Formation, and in the northern lowlands proximal to the north polar cap. In this study, crater fill material refers to an interior mound, generally separated f...

This paper presents the results of an experimental study to evaluate the damage and failure mode of hybrid-fiber engineered cementitious composite (ECC) panels caused by large projectiles or fragments with the aim towards quantifying the extent to which hybrid-fiber ECC improves the resistance of blast panels against impact loading. Drop weight tests are conducted on full-scale blast/shelter pa...

Impact diamonds were found in several inipactites from the Ries crater. Geriiiaiiy including fallout and fallback (crater f i l l ) suevites. a glass bomb, impact melt i-ock and shocked gneiss. These diamonds formed two distinct grain size populations: 50-300 pii apographitic. platy aggregates with surface ornamentation and etching that \vere observed using optical and scanning electron microsc...

The Lonar impact crater in the Deccan Traps of the Indian peninsula provides unique opportunities to study physical and chemical processes of impact cratering on basaltic targets, because terrestrial impact craters on basalts are extremely rare. Such studies are needed for determining provenance and other parameters of the excavated rocks and the cratering phenomenon that may have implications ...

0019-1035/$ see front matter 2011 Elsevier Inc. A doi:10.1016/j.icarus.2011.10.004 ⇑ Corresponding author. E-mail address: [email protected] (V.J. Bray). The morphology of impact craters on the icy Galilean satellites differs from craters on rocky bodies. The differences are thought due to the relative weakness of ice and the possible presence of sub-surface water layers. Digital elevation...

Samples from a 1.76-kilometer-deep corehole drilled near the center of the late Eocene Chesapeake Bay impact structure (Virginia, USA) reveal its geologic, hydrologic, and biologic history. We conducted stratigraphic and petrologic analyses of the cores to elucidate the timing and results of impact-melt creation and distribution, transient-cavity collapse, and ocean-water resurge. Comparison of...

The Chicxulub impact crater, México, is unique. It is the only known terrestrial impact structure that has been directly linked to a mass extinction event and the only terrestrial impact with a global ejecta layer. Of the three largest impact structures on Earth, Chicxulub is the best preserved. Chicxulub is also the only known terrestrial impact structure with an intact, unequivocal topographi...