Gravity study of the crustal structures of Somalia along International Lithosphere Program geotransects

Rapolla, A.; Cella, Federico; Dorre, A.S.

doi:10.1016/0899-5362(95)00053-v

Cited by 9 publications

(12 citation statements)

References 18 publications

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“…However, the amplitudes of these variations (which are related to density variations), a few tens of kilometer are much smaller than those of the Moho undulations presented on the present study (a few hundreds of kilometer). This result is in agreement with previous results [20] [34] [35] who ensure that the range wavelengths of the crust-mantle interfaces usually of a few hundred kilometers, even though shorter wavelengths may exist in rifts or continental margins [36]. Additionally, seismic refraction studies [26] [31] suggest that most of the crust in Cameroon is devoid of low-velocity layer.…”

Section: Discussion On the Origin And Age Of The Moho Undulationssupporting

confidence: 82%

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Topography of the Moho Undulation in Cameroon from Gravity Data: Preliminary Insights into the Origin, the Age and the Structure of the Crust and the Upper Mantle across Cameroon and Adjacent Areas

Eyike¹,

Nyam²,

Basseka³

2018

OJG

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In this paper, the complete Bouguer anomaly data from Cameroon and part of the neighboring countries has been examined to compute the topography of the Moho undulations. This work is based on an improved filtering technique and an appropriate density contrast between the crust and the upper mantle. Comparison with seismic data shows that our Moho map defines better the continuity and morphology of the crust-mantle interface than the scattered seismic data in Cameroon. The present relief map, although may not give real depths at some areas provides a better surface correlation with the surface geology better than seismic techniques. Comparison between the Moho undulations and the topography maps reveals that the crust in Cameroon seems to not be in isostatic equilibrium. The Moho in the Central African Shear Zone (CASZ) must be linked with different dextral movements during the opening of the south Atlantic in the Cretaceous time. In the Chad basin, the Moho is associated to the opening of the central and south Atlantic ~130 Ma. In the case of the Congo basin, the Moho undulations are related to the post rift subsidence. The correlation between the Moho undulations map with the surface geology indicates that the actual morphology of the crust mantle interface in Cameroon can be related to the build-up of the West and Central African rift system dating back to the Early Cretaceous to Palaeogene, where the presence of intraplate tensional stresses reactivated previous shear zones of lithospheric weakness during the break up of Gondwana.

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Section: Discussion On the Origin And Age Of The Moho Undulationssupporting

confidence: 82%

“…It is therefore necessary to remove short wavelength signals due to intracrustal sources and long wavelength signals caused by [20] we compute a set of filtered maps, adopting cut-off wavelengths (λ) varying from 200 to 700 km.…”

Section: Filteringmentioning

confidence: 99%

Topography of the Moho Undulation in Cameroon from Gravity Data: Preliminary Insights into the Origin, the Age and the Structure of the Crust and the Upper Mantle across Cameroon and Adjacent Areas

Eyike¹,

Nyam²,

Basseka³

2018

OJG

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“…The Marda Range has also been interpreted as a graben structure, presumably inverted, extending SE into Somalia as the Hiraan Rift (Bosellini 1989), also called the Wabe Shebele Rift (Rapolla et al 1995), and suggested to be of Permian to Jurassic age. This 'rift' is reported to be defined on gravity data and inferred from the drainage system (Sommavilla et al 1993) but neither gravity nor Fig.…”

Section: Geological Observationsmentioning

confidence: 97%

A major dyke swarm in the Ogaden region south of Afar and the early evolution of the Afar triple junction

Mège

Purcell²,

Bézos

et al. 2015

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“…The tectonic element map of the East Africa onshore and offshore (modified after Commission for the Geological Map of the World, ; Rapolla et al, ; Tanzania Petroleum Development Corporation Promotion Brochure, ). Backdrop: Free air gravity map (Sandwell et al, ).…”

Section: Crustal Architecture and Tectonic Elementsmentioning

confidence: 99%

“…During the end of Jurassic, the normal fault controlled breakup between Majunga (Madagascar)-Somalia and Beira Region-Antarctica was followed by organized sea-floor spreading creating a normal organized Figure 9. The tectonic element map of the East Africa onshore and offshore (modified after Commission for the Geological Map of the World, 1990;Rapolla et al, 1995;Tanzania Petroleum Development Corporation Promotion Brochure, 2009). Backdrop: Free air gravity map (Sandwell et al, 2014…”

Section: Breakup Localization and Geodynamic Evolutionmentioning

confidence: 99%

Crustal Architecture and Nature of Continental Breakup Along a Transform Margin: New Insights From Tanzania‐Mozambique Margin

Sinha

Saha

Longacre³

et al. 2019

Tectonics

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The Tanzania‐North Mozambique continental margin is a transform segment associated with Davie Fracture Zone (DFZ). The DFZ is described as an elongated linear oceanic fracture zone, commonly linked with the breakup between Eastern and Western Gondwana. We conducted a synthesized study using gravity, magnetic, and seismic data presenting the crustal architecture, geometry, and the kinematic nature of continental breakup along a transform margin. The crustal nature of DFZ, its role in forming kinematic linkage between two extensional margins during continental breakup processes, is focus of our study. The two extensional margins, Somalia‐Majunga and North Mozambique‐Antarctica, were linked via a 2,600‐km‐long dextral transform segment, partially overlapping with DFZ. Absence of classical rift indicators, weak signs of hyperextension, and abrupt ocean‐continent boundary suggest transform margin architecture. We redefined this feature as the Davie Transform System. The nature of deformation varies from transtensional pull‐apart in Tanzania to almost pure strike slip in North Mozambique. The southern transform segment exhibits abrupt change in ocean continent transition with a narrow zone of continental extension. This variation is recognized through the newly interpreted ocean‐continent boundary along this entire transform segment. Notably, within large pull‐apart systems in the north, the presence of fossilized incipient spreading center suggests that the extension had reached at quite advanced stages, characterized by significant thermal weakening as a consequence of strong magmatic activity. Through a series of reconstruction snapshots, we show the geodynamic evolution along the Tanzania‐North Mozambique margin explaining the role of Davie Transform System in the southward movement of Madagascar.

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Gravity study of the crustal structures of Somalia along International Lithosphere Program geotransects

Cited by 9 publications

References 18 publications

Topography of the Moho Undulation in Cameroon from Gravity Data: Preliminary Insights into the Origin, the Age and the Structure of the Crust and the Upper Mantle across Cameroon and Adjacent Areas

Topography of the Moho Undulation in Cameroon from Gravity Data: Preliminary Insights into the Origin, the Age and the Structure of the Crust and the Upper Mantle across Cameroon and Adjacent Areas

A major dyke swarm in the Ogaden region south of Afar and the early evolution of the Afar triple junction

Crustal Architecture and Nature of Continental Breakup Along a Transform Margin: New Insights From Tanzania‐Mozambique Margin

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