Abstract
To reveal the origin of a backstop and its influence on the evolution of the accretionary prism, we analyzed reflection seismic data acquired in the Nankai Trough off the Kii Peninsula. The deformation features of the forearc basin sequence show that the landward accretionary prism close to the coast was not deformed after the development of the forearc basin about 2-4 Ma. The surface of the landward prism can be identified as strong amplitude reflector, indicating that the landward prism has higher seismic velocity. Therefore, the landward accretionary prism inferred to be of higher strength constitutes a static backstop. Based on seismic and geologic observations, we interpret that the backstop was generated due to the large age differences of accreted material resulting from an inferred hiatus in subduction between ~13 and 6 Ma. The time-dependent processes such as the igneous activity in middle Miocene further contribute to the development of the backstop. A ridge structure beneath the forearc basin located trenchward of this backstop and running roughly parallel to it appears to reflect activity on an ancient splay fault. The strike of the ancient splay fault runs parallel to the backstop identified in this study and oblique to the current trench. This geometry suggests that location and mechanical behavior of this splay fault system is influenced by the backstop, and its distribution could be related to the coseismic rupture area.
| Original language | English |
|---|---|
| Pages (from-to) | 15-25 |
| Number of pages | 11 |
| Journal | Earth and Planetary Science Letters |
| Volume | 431 |
| DOIs | |
| Publication status | Published - Dec 1 2015 |
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All Science Journal Classification (ASJC) codes
- Geophysics
- Geochemistry and Petrology
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science
Cite this
Identification of the static backstop and its influence on the evolution of the accretionary prism in the Nankai Trough. / Tsuji, Takeshi; Ashi, Juichiro; Strasser, Michael; Kimura, Gaku.
In: Earth and Planetary Science Letters, Vol. 431, 01.12.2015, p. 15-25.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Identification of the static backstop and its influence on the evolution of the accretionary prism in the Nankai Trough
AU - Tsuji, Takeshi
AU - Ashi, Juichiro
AU - Strasser, Michael
AU - Kimura, Gaku
PY - 2015/12/1
Y1 - 2015/12/1
N2 - To reveal the origin of a backstop and its influence on the evolution of the accretionary prism, we analyzed reflection seismic data acquired in the Nankai Trough off the Kii Peninsula. The deformation features of the forearc basin sequence show that the landward accretionary prism close to the coast was not deformed after the development of the forearc basin about 2-4 Ma. The surface of the landward prism can be identified as strong amplitude reflector, indicating that the landward prism has higher seismic velocity. Therefore, the landward accretionary prism inferred to be of higher strength constitutes a static backstop. Based on seismic and geologic observations, we interpret that the backstop was generated due to the large age differences of accreted material resulting from an inferred hiatus in subduction between ~13 and 6 Ma. The time-dependent processes such as the igneous activity in middle Miocene further contribute to the development of the backstop. A ridge structure beneath the forearc basin located trenchward of this backstop and running roughly parallel to it appears to reflect activity on an ancient splay fault. The strike of the ancient splay fault runs parallel to the backstop identified in this study and oblique to the current trench. This geometry suggests that location and mechanical behavior of this splay fault system is influenced by the backstop, and its distribution could be related to the coseismic rupture area.
AB - To reveal the origin of a backstop and its influence on the evolution of the accretionary prism, we analyzed reflection seismic data acquired in the Nankai Trough off the Kii Peninsula. The deformation features of the forearc basin sequence show that the landward accretionary prism close to the coast was not deformed after the development of the forearc basin about 2-4 Ma. The surface of the landward prism can be identified as strong amplitude reflector, indicating that the landward prism has higher seismic velocity. Therefore, the landward accretionary prism inferred to be of higher strength constitutes a static backstop. Based on seismic and geologic observations, we interpret that the backstop was generated due to the large age differences of accreted material resulting from an inferred hiatus in subduction between ~13 and 6 Ma. The time-dependent processes such as the igneous activity in middle Miocene further contribute to the development of the backstop. A ridge structure beneath the forearc basin located trenchward of this backstop and running roughly parallel to it appears to reflect activity on an ancient splay fault. The strike of the ancient splay fault runs parallel to the backstop identified in this study and oblique to the current trench. This geometry suggests that location and mechanical behavior of this splay fault system is influenced by the backstop, and its distribution could be related to the coseismic rupture area.
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UR - http://www.scopus.com/inward/citedby.url?scp=84942095944&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2015.09.011
DO - 10.1016/j.epsl.2015.09.011
M3 - Article
AN - SCOPUS:84942095944
VL - 431
SP - 15
EP - 25
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
SN - 0012-821X
ER -