Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Origin of small pits in martian impact craters
AU - Boyce, Joseph M.
AU - Wilson, Lionel
AU - Mouginis-Mark, Peter J.
AU - Hamilton, Christopher W.
AU - Tornabene, Livio L.
PY - 2012
Y1 - 2012
N2 - We propose a numerical model for the formation of the closely-spaced pits found in the thin, ejecta-related deposits superposed on the floors, interior terrace blocks, and near-rim ejecta blankets of well-preserved martian impact craters. Our model predicts the explosive degassing of water from this pitted material, which is assumed to originally be water-bearing, impact melt-rich breccia at the time of deposition. This process is analogous to what occurred in the fall-out suevite deposits at the Ries impact structure in Germany. At Ries, impact heating of water-bearing target material resulted in the rapid degassing of its water and other volatiles. The martian environment plays an important role in enhancing the effects of this degassing by increasing the flow-speed of the escaping gas. The high flow-rate of gas through particulate materials, such as suevite, tends to quickly form segregation channels or vent pipes, similar to those found in the Ries deposits. These pipes act as conduits for the efficient high-speed escape of the gas and small clasts that it entrains. Escaping gas and entrained clasts abraded and eroded the conduit walls, flaring them to form pits above a network of pipes.
AB - We propose a numerical model for the formation of the closely-spaced pits found in the thin, ejecta-related deposits superposed on the floors, interior terrace blocks, and near-rim ejecta blankets of well-preserved martian impact craters. Our model predicts the explosive degassing of water from this pitted material, which is assumed to originally be water-bearing, impact melt-rich breccia at the time of deposition. This process is analogous to what occurred in the fall-out suevite deposits at the Ries impact structure in Germany. At Ries, impact heating of water-bearing target material resulted in the rapid degassing of its water and other volatiles. The martian environment plays an important role in enhancing the effects of this degassing by increasing the flow-speed of the escaping gas. The high flow-rate of gas through particulate materials, such as suevite, tends to quickly form segregation channels or vent pipes, similar to those found in the Ries deposits. These pipes act as conduits for the efficient high-speed escape of the gas and small clasts that it entrains. Escaping gas and entrained clasts abraded and eroded the conduit walls, flaring them to form pits above a network of pipes.
KW - EMPLACEMENT
KW - FLUIDIZATION
KW - HYDROTHERMAL SYSTEMS
KW - Mars, Surface
KW - MELT
KW - Geological processes
KW - Terrestrial planets
KW - RIES
KW - DEPOSITS
KW - Cratering
KW - PYROCLASTIC FLOWS
KW - EJECTA
KW - Impact processes
KW - EXPLOSIVE VOLCANIC-ERUPTIONS
KW - MARS
U2 - 10.1016/j.icarus.2012.07.027
DO - 10.1016/j.icarus.2012.07.027
M3 - Journal article
VL - 221
SP - 262
EP - 275
JO - Icarus
JF - Icarus
SN - 0019-1035
IS - 1
ER -