Complex seismic anisotropy in Madagascar revealed by shear-wave splitting measurements
Complex seismic anisotropy in Madagascar revealed by shear-wave splitting measurements
复制标题
通过剪切波分裂测量揭示马达加斯加复杂的地震各向异性
DOI：
10.1093/gji/ggy367
复制
发表时间：
2018
影响因子：
2.8
通讯作者：
T. Rakotondraibe
中科院分区：
文献类型：
--
作者：
Cristo Ramirez;A. Nyblade;M. Wysession;Martin Pratt;F. Andriampenomanana;T. Rakotondraibe
本文报道了分布在马达加斯加全境的25个临时地震台和2个永久地震台的SKS和SKKS分裂测量资料，得到的横波快偏振方向（Φ）和延迟时间（δt）。结果表明，Φ的复杂模式，是不容易解释的单一来源的各向异性，如化石各向异性在岩石圈或地幔流从非洲超级羽或绝对板块运动。为了解释结果，我们将该岛分为四个区域。该岛北方部分的特征是一个NEENE-WSW Φ模式，这可以归因于东北方向的地幔流从非洲超级地幔柱或板块运动的修改SE方向的地幔流从科摩罗热点。在岛的中心，观察到一个大致圆形的Φ图案，可以归因于上涌的软流圈，由岩石圈拆沉引起，与来自超级地幔柱或板块运动的地幔流相互作用。小规模的地幔流也可以用来解释一个单独的半圆形Φ模式在西南部的岛屿。在岛的中南部和东南部，Φ在许多台站平行于剪切带的NW走向，可以归因于岩石圈中的化石各向异性。然而，东北方向的快速极化方向沿着该地区的北方边缘不符合剪切带的方向，而可能是圆形Φ图案的一部分，其特征是岛的中心部分。
Shear wave fast polarization directions (Φ) and delay times (δt) obtained from SKS and SKKS splitting measurements are reported for 25 temporary and 2 permanent seismic stations distributed throughout Madagascar. Results show a complicated pattern of Φ that is not easily explained by a single source of anisotropy, such as fossil anisotropy in the lithosphere or mantle flow from the African superplume or absolute plate motion. To interpret the results, we divide the island into four areas. The northern part of the island is characterized by an ∼ENE–WSW Φ pattern, which can be attributed to NE-oriented mantle flow from the African superplume or plate motion modified by SE-oriented mantle flow from the Comoros hotspot. In the centre of the island, a roughly circular Φ pattern is observed and can be attributed to upwelling asthenosphere, caused by lithospheric delamination, interacting with mantle flow from the superplume or plate motion. Small-scale mantle flow can also be invoked to explain a separate semi-circular Φ pattern in the southwestern part of the island. In the south–central and southeastern parts of the island, Φ is parallel to the NW strike of shear zones at many stations and can be attributed to fossil anisotropy in the lithosphere. However, NE-oriented fast polarization directions along the northern edge of this area do not align with the orientation of shear zones and could instead be part of the circular Φ pattern that characterizes the central part of the island.
马达加斯加下方地壳和最上地幔的结构
影响因子：
2.8
作者：
Andriampenomanana;Nyblade;Wysession;Durrheim;Tilmann;Julià;Rambolamanana;Aleqabi;Rakotondraibe
通讯作者：
Rakotondraibe
DOI：
10.1002/2016jb013020
发表时间：
2016-09
期刊：
Journal of Geophysical Research: Solid Earth
影响因子：
--
作者：
M. Reiss;G. Rümpker;F. Tilmann;X. Yuan;J. Giese;E. Rindraharisaona
通讯作者：
M. Reiss;G. Rümpker;F. Tilmann;X. Yuan;J. Giese;E. Rindraharisaona