Details
| Original language | English |
|---|---|
| Pages (from-to) | 49-58 |
| Number of pages | 10 |
| Journal | Earth and Planetary Science Letters |
| Volume | 474 |
| Issue number | 474 |
| Publication status | Published - 15 Sept 2017 |
| Externally published | Yes |
Abstract
Using Coulomb wedge solutions, we show that the effective strength of megathrusts (μ b ′) can be determined from the geometry of out-of-sequence thrusts cutting through an accretionary or orogenic wedge. The method is first tested on central Chilean margin for which it yields a frictional strength of μ b ′=0.053 (+0.043/−0.024). The inferred value agrees well with previous strength estimates and with the tectonic response of the central Chilean wedge to 2010 M w 8.8 Maule earthquake. We then use the approach to constrain the strength of the collision megathrust of the central European Alps ∼30–20 million years ago. We find that the collision megathrust had a strength of μ b ′=0.065 (+0.035/−0.026), which is similarly low than the strength of subduction megathrusts. The result is integrated into a static force balance model to examine potential implications of a weak megathrust for the Alpine orogeny. The model results suggest that the Alpine megathrust supported a mean maximum elevation of ∼2,000 m and that growth of the wedge up to this elevation supported a switch from contractional to extensional tectonics in the interior of the Alps around 20 Ma. Finally, using the example of the Himalayas, we show how the strength of megathrusts may be also derived from the geometry of crustal ramps, which provides a valuable alternative if details on out-of-sequence thrusts are missing.
Keywords
- Coulomb wedge, continental collision, crustal ramp, megathrust, out-of-sequence thrust, subduction
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geophysics
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
- Earth and Planetary Sciences(all)
- Earth and Planetary Sciences (miscellaneous)
- Earth and Planetary Sciences(all)
- Space and Planetary Science
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In: Earth and Planetary Science Letters, Vol. 474, No. 474, 15.09.2017, p. 49-58.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Constraining the strength of megathrusts from fault geometries and application to the Alpine collision zone
AU - Dielforder, Armin
N1 - Publisher Copyright: © 2017 Elsevier B.V.
PY - 2017/9/15
Y1 - 2017/9/15
N2 - Using Coulomb wedge solutions, we show that the effective strength of megathrusts (μ b ′) can be determined from the geometry of out-of-sequence thrusts cutting through an accretionary or orogenic wedge. The method is first tested on central Chilean margin for which it yields a frictional strength of μ b ′=0.053 (+0.043/−0.024). The inferred value agrees well with previous strength estimates and with the tectonic response of the central Chilean wedge to 2010 M w 8.8 Maule earthquake. We then use the approach to constrain the strength of the collision megathrust of the central European Alps ∼30–20 million years ago. We find that the collision megathrust had a strength of μ b ′=0.065 (+0.035/−0.026), which is similarly low than the strength of subduction megathrusts. The result is integrated into a static force balance model to examine potential implications of a weak megathrust for the Alpine orogeny. The model results suggest that the Alpine megathrust supported a mean maximum elevation of ∼2,000 m and that growth of the wedge up to this elevation supported a switch from contractional to extensional tectonics in the interior of the Alps around 20 Ma. Finally, using the example of the Himalayas, we show how the strength of megathrusts may be also derived from the geometry of crustal ramps, which provides a valuable alternative if details on out-of-sequence thrusts are missing.
AB - Using Coulomb wedge solutions, we show that the effective strength of megathrusts (μ b ′) can be determined from the geometry of out-of-sequence thrusts cutting through an accretionary or orogenic wedge. The method is first tested on central Chilean margin for which it yields a frictional strength of μ b ′=0.053 (+0.043/−0.024). The inferred value agrees well with previous strength estimates and with the tectonic response of the central Chilean wedge to 2010 M w 8.8 Maule earthquake. We then use the approach to constrain the strength of the collision megathrust of the central European Alps ∼30–20 million years ago. We find that the collision megathrust had a strength of μ b ′=0.065 (+0.035/−0.026), which is similarly low than the strength of subduction megathrusts. The result is integrated into a static force balance model to examine potential implications of a weak megathrust for the Alpine orogeny. The model results suggest that the Alpine megathrust supported a mean maximum elevation of ∼2,000 m and that growth of the wedge up to this elevation supported a switch from contractional to extensional tectonics in the interior of the Alps around 20 Ma. Finally, using the example of the Himalayas, we show how the strength of megathrusts may be also derived from the geometry of crustal ramps, which provides a valuable alternative if details on out-of-sequence thrusts are missing.
KW - Coulomb wedge
KW - continental collision
KW - crustal ramp
KW - megathrust
KW - out-of-sequence thrust
KW - subduction
UR - http://www.scopus.com/inward/record.url?scp=85032664639&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2017.06.021
DO - 10.1016/j.epsl.2017.06.021
M3 - Article
VL - 474
SP - 49
EP - 58
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
SN - 0012-821X
IS - 474
ER -