| Title | The subsurface character of meteor crater, Arizona, as determined by ground - probing radar |
| |
| Author | Pilon, J A; Grieve, R A F; Sharpton, V L |
| Source | Journal of Geophysical Research vol. 96, no. E1, 1991 p. 15563-15576, https://doi.org/10.1029/91je01114 |
| Image |  |
| Year | 1991 |
| Alt Series | Geological Survey of Canada, Contribution Series 21890 |
| Publisher | Wiley-Blackwell |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Area | Canyon Diablo Area; Arizona; United States of America |
| Lat/Long WENS | -111.0333 -111.0000 35.0500 35.0167 |
| Subjects | stratigraphy; extraterrestrial geology; geophysics; structural geology; meteorite craters; structural features; ground probing radar; geophysical surveys; water table; faults; Colorado Plateau; Moenkopi
Formation; Kaibab Formation |
| Illustrations | tables; photographs; cross-sections; radar profiles |
| Released | 2012 09 21 |
| Abstract | Ground-probing radar has provided new two-dimensional stratigraphic and structural information on Meteor Crater, Arizona. Four 50-MHz transects inside the crater and one 100-MHz transect on a northeast
radial across the exterior ejecta blanket were carried out. The frequencies used were in relation to the desired depth of investigation: greater than 50 m at 50 MHz and ~30 m for 100 MHz. The results obtained inside the crater show that the water
table can be clearly detected at depths of ~65 m, as can the contact between the crater wall and the infilling allochthonous breccia lens. In addition, we were able to detect (1) point reflectors from relatively coherent blocks (>1.5m) within the
breccia lens, (2) a zone ~7 m thick relatively free of point reflectors from the immediate fall back unit, (3) a series of subhorizontal reflectors a few meters apart due to bedding in the post impact crater sediments, and (4) five separate
subhorizontal reflectors from what we interpret to be a series of postimpact paleo-water table levels in the breccia lens. The ejecta blanket transect indicates a ~4–10 m thick ejecta layer and the underlying Moenkopi Formation sandstone, as well as
the Moenkopi-Kaibab contact and bedding within the Kaibab Formation. In addition, reverse faults with displacements up to 4 m were detected in the bedrock, as well as changes from subhorizontal to ~30° in the dip of the bedrock as the crater rim is
approached from the northeast. Beneath the ejecta blanket, the total uplift observed at the crater rim is around 55 m. The radar data indicate uplift effects out to a radial distance of ~400 m from the rim, farther than that determined from drilling
(~300 m). The results demonstrate the utility of continuous ground-probing radar cross sections in studying the near-subsurface (~50 m) character at Meteor Crater. This relatively rapid, low cost technique can be extended to other structures, but
confident interpretation requires supplemental ground truth constraints. |
| GEOSCAN ID | 132164 |
|
|