| Autor: |
Cole HM; Department of Geophysics, Colorado School of Mines, Golden CO 80401., Andrews-Hanna JC; Southwest Research Institute, Boulder, CO 80302.; now at the Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092. |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of geophysical research. Planets [J Geophys Res Planets] 2017 May; Vol. 122 (5), pp. 889-900. |
| DOI: |
10.1002/2017JE005274 |
| Abstrakt: |
Wrinkle ridges are among the most common tectonic structures on the terrestrial planets, and provide important records of the history of planetary strain and geodynamics. The observed broad arches and superposed narrow wrinkles are thought to be the surface manifestation of blind thrust faults, which terminate in near-surface volcanic sequences and cause folding and layer-parallel shear. However, the subsurface tectonic architecture associated with the ridges remains a matter of debate. Here we present direct observations of a wrinkle ridge thrust fault where it has been exposed by erosion in the southern wall of Melas Chasma on Mars. The thrust fault has been made resistant to erosion, likely due to volcanic intrusion, such that later erosional widening of the trough exposed the fault plane as a 70 km-long ridge extending into the chasma. A plane fit to this ridge crest reveals a thrust fault with a dip of 13° (+8°, -7°) between 1 and 3.5 km depth below the plateau surface, with no evidence for listric character in this depth range. This dip is significantly lower than the commonly assumed value of 30°, which, if representative of other wrinkle ridges, indicates that global contraction on Mars may have been previously underestimated. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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