The structure of the crust and uppermost mantle beneath Madagascar
The structure of the crust and uppermost mantle beneath Madagascar
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马达加斯加下方地壳和最上地幔的结构
DOI：
10.1093/gji/ggx243
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发表时间：
2017
影响因子：
2.8
通讯作者：
Rakotondraibe
中科院分区：
文献类型：
--
作者：
Andriampenomanana;Nyblade;Wysession;Durrheim;Tilmann;Julià;Rambolamanana;Aleqabi;Rakotondraibe
马达加斯加岩石圈最初是在新元古代泛非事件期间合并的。随后，在侏罗纪和白垩纪分别与非洲和印度分离的伸展作用下，它被重塑，并受到晚白垩纪和新生代的几次岩浆事件的影响。本研究对马达加斯加的地壳和上地幔进行了研究，以深入了解马达加斯加现今的构造和构造演化。利用h- κ叠加法和瑞利波相速度联合反演，对37个宽带地震台站的接收函数进行了分析。马达加斯加地壳的厚度在18到46公里之间。它通常在中部山脉脊下较厚（厚度可达46公里），向岛屿边缘方向厚度逐渐减小。最浅的莫霍是在西部沉积盆地（18公里厚）下发现的，这些盆地形成于冈瓦纳二叠-三叠纪Karro裂谷和东非马达加斯加的侏罗纪裂谷。沉积盆地下方地壳向北、向东加厚，反映了盆地的渐进性发育。相比之下，东部地区没有发生大的裂谷事件。相反，东海岸地壳的轻微变薄（31-36公里厚）可能是由于马达加斯加移动到马里恩热点和印度从马里恩热点分离出来时地壳的隆起和侵蚀造成的。描述太古宙和元古代地体地壳结构的参数，包括平均厚度（40 km vs 35 km）、泊松比（0.25 vs 0.26）、平均横波速度（均为3.7 km s-1）和基性下地壳厚度（7 km vs 4 km），显示出较弱的长期变化证据。马达加斯加地下的最上层地幔通常具有稳定岩石圈的典型剪切波速度（~ 4.5 km s-1）。然而，在新生代主要火山省所在的岛北端、中部和西南地区，观察到明显缓慢的横波速度（4.2-4.3 km s-1），这表明这些地方的岩石圈已经发生了明显的变化。
The lithosphere of Madagascar was initially amalgamated during the Pan-African events in the Neoproterozoic. It has subsequently been reshaped by extensional processes associated with the separation from Africa and India in the Jurassic and Cretaceous, respectively, and been subjected to several magmatic events in the late Cretaceous and the Cenozoic. In this study, the crust and uppermost mantle have been investigated to gain insights into the present-day structure and tectonic evolution of Madagascar. We analysed receiver functions, computed from data recorded on 37 broad-band seismic stations, using theH–κstacking method and a joint inversion with Rayleigh-wave phase-velocity measurements. The thickness of the Malagasy crust ranges between 18 and 46 km. It is generally thick beneath the spine of mountains in the centre part (up to 46 km thick) and decreases in thickness towards the edges of the island. The shallowest Moho is found beneath the western sedimentary basins (18 km thick), which formed during both the Permo-Triassic Karro rifting in Gondwana and the Jurassic rifting of Madagascar from eastern Africa. The crust below the sedimentary basin thickens towards the north and east, reflecting the progressive development of the basins. In contrast, in the east there was no major rifting episode. Instead, the slight thinning of the crust along the east coast (31–36 km thick) may have been caused by crustal uplift and erosion when Madagascar moved over the Marion hotspot and India broke away from it. The parameters describing the crustal structure of Archean and Proterozoic terranes, including average thickness (40 km versus 35 km), Poisson's ratio (0.25 versus 0.26), average shear-wave velocity (both 3.7 km s–1), and thickness of mafic lower crust (7 km versus 4 km), show weak evidence of secular variation. The uppermost mantle beneath Madagascar is generally characterized by shear-wave velocities typical of stable lithosphere (∼4.5 km s–1). However, markedly slow shear-wave velocities (4.2–4.3 km s–1) are observed beneath the northern tip, central part and southwestern region of the island where the major Cenozoic volcanic provinces are located, implying the lithosphere has been significantly modified in these places.
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影响因子：
5.3
作者：
D. Thompson;I. Bastow;G. Helffrich;J. Kendall;J. Wookey;D. Snyder;D. Eaton
通讯作者：
D. Thompson;I. Bastow;G. Helffrich;J. Kendall;J. Wookey;D. Snyder;D. Eaton
影响因子：
2.9
作者：
M. Pasyanos;A. Nyblade
通讯作者：
M. Pasyanos;A. Nyblade
马达加斯加中部地区震源参数和构造速度同步反演作为塔那那利佛减灾的前提
DOI：
--
发表时间：
1997
期刊：
影响因子：
--
作者：
G. Rambolamanana;P. Suhadolc;G. Panza
通讯作者：
G. Panza
马达加斯加的地质演化：简介
DOI：
--
发表时间：
1999
期刊：
影响因子：
--
作者：
A. Piqué
通讯作者：
A. Piqué
马达加斯加地质概况
DOI：
--
发表时间：
1982
期刊：
影响因子：
--
作者：
J. Boast;A. Nairn
通讯作者：
A. Nairn