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| Titel |
Recent (Late Amazonian) enhanced backweathering rates on Mars: Paracratering evidence from gully alcoves |
| VerfasserIn |
Tjalling de Haas, Susan Conway, Michael Krautblatter |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250124729
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| Publikation (Nr.) |
 EGU/EGU2016-4208.pdf |
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| Zusammenfassung |
| Mars is believed to have been exposed to low planet-wide weathering and denudation
since the Noachian period (∼4.1 - 3.7 Ga). However, the widespread occurrence
of alcoves at the rim of pristine impact craters suggests locally enhanced recent
backweathering rates. Here we derive Late Amazonian backweathering rates from the
alcoves of 10 young equatorial and mid-latitude craters, ranging in age from 0.2 to 45
Ma.
The enhanced Late Amazonian Martian backweathering rates (10−4 - 10−1 mm
yr−1) are approximately one order of magnitude higher than previously reported
erosion rates, and are similar to terrestrial rates inferred from Meteor crater and
various Arctic and Alpine rock faces, when corrected for age. Alcoves on initially
highly fractured and oversteepened crater rims following impact show enhanced
backweathering rates that decline over at least 101 - 102 Myr as the crater wall
stabilizes. This ‘paracratering’ backweathering decline with time is analogous to
the paraglacial effect observed in rock slopes after deglaciation, but the relaxation
time scale of 101 - 102 Myr compared to 10 kyr of the Milankovitch-controlled
interglacial duration questions whether a paraglacial steady state is reached on
Earth.
The backweathering rates on the gullied pole-facing alcoves of the studied mid-latitude
craters are much higher (∼2 - 60 times) than those on slopes with other azimuths and those in
equatorial craters. The enhanced backweathering rates on gullied crater slopes may result
from liquid water acting as a catalyst for backweathering. The decrease in backweathering
rates over time might explain the similar size of gullies in young (<1 Ma) and much older
craters, as alcove growth and sediment supply decrease to low background rates over time. |
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