Assembly and breakup of Gondwana - seismological signatures in the lithosphere/asthenosphere system of Southern Madagascar (SELASOMA)

冈瓦纳大陆的组装和分裂 - 马达加斯加南部岩石圈/软流圈系统中的地震特征（SELASOMA）

• 批准号: 267795306
• 负责人: Professor Dr. Georg Rümpker
• 金额: --
• 依托单位: Geological Survey of Norway (NGU)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/267795306?language=en
• 关键词: Assembly; breakup; Gondwana; seismological; signatures

The assembly and destruction of supercontinents in the Wilson cycle is one of the defining paradigms for understanding the plate tectonic history beyond the time recorded by seafloor magnetic lineations. In this context the question arises to what extent the location and mode of breakup is controlled by ancient fabric formed during earlier cycles. Complementary to this issue is the question to what extent major episodes of suturing or rifting overprint earlier fabric, and how these earlier events influence recent kinematics. Whereas these questions have been addressed extensively by geological investigations, the dynamics of these processes are likely to be strongly influenced by the rheology of the mid- and lower crust and the mantle part of the lithosphere, best characterised by seismological investigations. The island of Madagascar occupied a key region in both the assembly and the multi-stage breakup of Gondwanaland (Stern 1994), itself part of the super-continent Pangaea. Madagascar consists of amalgamated continental material comprising several distinct tectonic units, with the oldest rocks being of Archaean age (3.2 Ga). Major geological boundaries generally follow a N-S trend mirroring the geographic orientation of the island. Its Proterozoic to early Paleozoic fabric is characterised by a shear-zone network spanning hundreds of kilometers, with some of the branches running oblique to the N-S trend, in particular in the south of the island. More recently during the Neogene, moderate volcanism has occurred in the Central and Northern part of the island, and there are indications of uplift throughout Eastern Madagascar over the last 10 Ma (Roberts et al. 2012). Although Madagascar is located within the interior of the African plate and far away from major plate boundaries, its seismic activity indicates that some deformation is taking place. Present-day kinematic models based on geodetic data and earthquake moment tensors identify a diffuse N-S-oriented minor boundary separating two microplates, which appears to pass through Madagascar (Stamps et al. 2008). Because of its key role in the assembly of Gondwana, numerous geological investigations have been carried out in Madagascar. However, comparatively little is known about the sub-surface structure as few focused seismological studies have been carried out in Madagascar. In this proposal we aim to characterise the lithospheric structure of southern Madagascar using data from a passive seismic experiment, which we carried out from May 2012 to May 2014. This experiment included an approximately E-W oriented profile of broadband stations across the island (operating for two years), and an areal array of short-period stations (operated for one year). The profile crosses all major geologic provinces and the short-period array will be used to map local seismicity and provide additional control on the 3-dimensional structure of the lithosphere/asthenosphere system.

威尔逊旋回中超大陆的聚集和破坏是理解海底磁力线线记录的时间之外的板块构造历史的典型范例之一。在这种情况下，问题出现了，在多大程度上，分裂的位置和模式是由早期旋回形成的古代构造控制的。与此问题相辅相成的是，在多大程度上缝合或撕裂早期织物的主要事件，以及这些早期事件如何影响最近的运动学。虽然这些问题已经通过地质调查得到了广泛的解决，但这些过程的动力学很可能受到岩石圈中、下地壳和地幔部分的流变学的强烈影响，地震学调查最能说明这一点。马达加斯加岛在冈瓦纳大陆的合并和多阶段分裂（Stern 1994）中都占据了一个关键区域，冈瓦纳大陆本身就是超大陆盘古大陆的一部分。马达加斯加由混合的大陆物质组成，包括几个不同的构造单元，最古老的岩石是太古宙时代（3.2 Ga）。主要的地质边界通常遵循南北向的趋势，反映了该岛的地理方向。它的元古代到早古生代构造的特点是一个跨越数百公里的剪切带网络，其中一些分支斜向南北走向，特别是在岛的南部。在最近的新近纪，该岛中部和北部发生了中度火山活动，在过去的10 Ma中，整个马达加斯加东部都有隆起的迹象（Roberts et al. 2012）。虽然马达加斯加位于非洲板块的内部，远离主要板块边界，但它的地震活动表明正在发生一些变形。目前基于大地测量数据和地震矩张量的运动学模型确定了一个分散的n - s方向的小边界，将两个微板块分开，似乎穿过马达加斯加（Stamps et al. 2008）。由于它在冈瓦纳火山聚集中的关键作用，在马达加斯加进行了许多地质调查。然而，由于在马达加斯加进行的集中地震学研究很少，对地下结构的了解相对较少。在本提案中，我们的目标是利用2012年5月至2014年5月进行的被动地震实验数据来表征马达加斯加南部岩石圈结构。这个实验包括一个大约东西向的全岛宽带站概况（运行了两年）和一个短周期站的区域阵列（运行了一年）。剖面跨越所有主要地质省，短周期阵列将用于绘制当地地震活动性，并提供对岩石圈/软流圈系统三维结构的额外控制。

项目成果

The structure of the crust and uppermost mantle beneath Madagascar

马达加斯加下方地壳和最上地幔的结构

• DOI: 10.1093/gji/ggx243
• 发表时间: 2017
• 期刊: Geophysical Journal International
• 影响因子: 2.8
• 作者: Andriampenomanana;Nyblade;Wysession;Durrheim;Tilmann;Julià;Rambolamanana;Aleqabi;Rakotondraibe
• 通讯作者: Rakotondraibe

Crustal structures in southern Madagascar and Sri Lanka in the context of Gondwana’s assembly and break-up: A study based on surface wave dispersion and receiver functions

冈瓦纳大陆组装和破碎背景下马达加斯加南部和斯里兰卡的地壳结构：基于表面波色散和接收函数的研究

• DOI: 10.17169/refubium-27001
• 发表时间: 2020
• 作者: Jennifer Dreiling

Seismic anisotropy of the lithosphere and asthenosphere beneath southern Madagascar from teleseismic shear wave splitting analysis and waveform modeling

• DOI: 10.1002/2016jb013020
• 发表时间: 2016-09
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: M. Reiss;G. Rümpker;F. Tilmann;X. Yuan;J. Giese;E. Rindraharisaona

Crustal Radial Anisotropy and Linkage to Geodynamic Processes: A Study Based on Seismic Ambient Noise in Southern Madagascar

• DOI: 10.1029/2017jb015273
• 发表时间: 2018-06
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: J. Dreiling;F. Tilmann;X. Yuan;J. Giese;E. Rindraharisaona;G. Rümpker;M. Wysession

Velocity structure and radial anisotropy of the lithosphere in southern Madagascar from surface wave dispersion

表面波色散研究马达加斯加南部岩石圈的速度结构和径向各向异性

• DOI: 10.1093/gji/ggaa550
• 发表时间: 1944
• 期刊: Geophysical Journal International
• 影响因子: 2.8
• 作者: Rindraharisaona;Tilmann;Dreiling;Priestley;Rümpker
• 通讯作者: Rümpker