| DOI: | 10.1016/j.epsl.2017.11.002
|
| Scopus记录号: | 2-s2.0-85033693209
|
| 论文题名: | Large-scale trench-normal mantle flow beneath central South America |
| 作者: | Reiss M.C.; Rümpker G.; Wölbern I.
|
| 刊名: | Earth and Planetary Science Letters
|
| ISSN: | 0012821X
|
| 出版年: | 2018
|
| 卷: | 482 | | 起始页码: | 115
|
| 结束页码: | 125
|
| 语种: | 英语
|
| 英文关键词: | central Andes
; crustal anisotropy
; shear-wave splitting
; trench-perpendicular mantle flow
|
| Scopus关键词: | Anisotropy
; Crystallography
; Earthquakes
; Faulting
; Flow fields
; Geophysics
; Polarization
; Shear flow
; Shear waves
; Silicate minerals
; Structural geology
; Absolute plate motions
; Central Andes
; Crustal anisotropy
; Crystallographic preferred orientations
; Mantle flow
; Polarization direction
; Shape preferred orientations
; Shear wave splitting
; Parallel flow
; crustal structure
; earthquake
; flow field
; mantle structure
; S-wave
; seismic anisotropy
; slab
; teleseismic wave
; trench
; wave splitting
; Andes
|
| 英文摘要: | We investigate the anisotropic properties of the fore-arc region of the central Andean margin between 17–25°S by analyzing shear-wave splitting from teleseismic and local earthquakes from the Nazca slab. With partly over ten years of recording time, the data set is uniquely suited to address the long-standing debate about the mantle flow field at the South American margin and in particular whether the flow field beneath the slab is parallel or perpendicular to the trench. Our measurements suggest two anisotropic layers located within the crust and mantle beneath the stations, respectively. The teleseismic measurements show a moderate change of fast polarizations from North to South along the trench ranging from parallel to subparallel to the absolute plate motion and, are oriented mostly perpendicular to the trench. Shear-wave splitting measurements from local earthquakes show fast polarizations roughly aligned trench-parallel but exhibit short-scale variations which are indicative of a relatively shallow origin. Comparisons between fast polarization directions from local earthquakes and the strike of the local fault systems yield a good agreement. To infer the parameters of the lower anisotropic layer we employ an inversion of the teleseismic waveforms based on two-layer models, where the anisotropy of the upper (crustal) layer is constrained by the results from the local splitting. The waveform inversion yields a mantle layer that is best characterized by a fast axis parallel to the absolute plate motion which is more-or-less perpendicular to the trench. This orientation is likely caused by a combination of the fossil crystallographic preferred orientation of olivine within the slab and entrained mantle flow beneath the slab. The anisotropy within the crust of the overriding continental plate is explained by the shape-preferred orientation of micro-cracks in relation to local fault zones which are oriented parallel to the overall strike of the Andean range. Our results do not provide any evidence for a significant contribution of trench-parallel mantle flow beneath the subducting slab. © 2017 Elsevier B.V. |
| Citation statistics: |
|
| 资源类型: | 期刊论文
|
| 标识符: | http://119.78.100.158/handle/2HF3EXSE/110150
|
| Appears in Collections: | 影响、适应和脆弱性
气候变化事实与影响
|
|
There are no files associated with this item.
|
|
作者单位: | Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, Frankfurt am Main, 60438, Germany
|
| Recommended Citation: | |
Reiss M.C.,Rümpker G.,Wölbern I.. Large-scale trench-normal mantle flow beneath central South America[J]. Earth and Planetary Science Letters,2018-01-01,482
|
|
|