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.

威尔逊周期中超级大陆的组装和破坏是理解海底磁线记录时间之外的板块构造历史的定义范式之一。在这种情况下，出现了一个问题：早期周期中形成的古代织物在多大程度上控制了破裂的位置和模式。与此问题互补的是早期织物缝合或裂痕叠印的主要事件在多大程度上以及这些早期事件如何影响最近的运动学的问题。尽管这些问题已通过地质调查得到广泛解决，但这些过程的动力学很可能受到中、下地壳和岩石圈地幔部分的流变学的强烈影响，而地震学调查最能表征这些流变学。马达加斯加岛在冈瓦纳大陆的组装和多阶段分裂中占据了关键区域（Stern 1994），它本身就是超级大陆盘古大陆的一部分。马达加斯加由合并的大陆物质组成，其中包括几个不同的构造单元，最古老的岩石为太古宙年龄（3.2 Ga）。主要地质边界通常遵循南北趋势，反映了岛屿的地理方向。其元古代至早古生代结构的特点是横跨数百公里的剪切带网络，其中一些分支与南北走向倾斜，特别是在该岛的南部。 最近，在新近纪期间，该岛的中部和北部发生了中度火山活动，并且有迹象表明整个马达加斯加东部在过去 10 Ma 中发生了隆起（Roberts 等，2012）。尽管马达加斯加位于非洲板块内部，远离主要板块边界，但其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分隔两个微板的弥散的 N-S 方向的小边界，该边界似乎穿过马达加斯加（Stamps 等人，2008 年）。由于其在冈瓦纳大陆组装中的关键作用，马达加斯加进行了大量的地质调查。然而，由于马达加斯加很少开展集中的地震学研究，因此人们对地下结构知之甚少。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的岩石圈结构。该实验包括全岛宽带站的大致东西向剖面（运行两个年），以及一系列短期站（运行一年）。该剖面跨越所有主要地质省份，短周期阵列将用于绘制当地地震活动图，并对岩石圈/软流圈系统的三维结构提供额外的控制。

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

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

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

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