The KRISP 94 lithospheric investigation of southern Kenya — the experiments and their main results

Prodehl, C.; Ritter, Joachim; Mechie, J.; Keller, G. Randy; Khan, M. Aftab; Jacob, B.; Fuchs, Karl; Nyambok, I O; Obel, J.D.; Riaroh, Don

doi:10.1016/s0040-1951(97)00098-x

Cited by 41 publications

(39 citation statements)

References 8 publications

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“…a wide or narrow rift; Buck 2004). Crustal thickness in the oblique southern Kenyan Rift is 35 km, broadly similar to the MER crustal thickness at 30-40 km (Prodehl et al 1997;Stuart et al 2006). Therefore, we cannot distinguish between these two rifts based on crustal thickness alone.…”

Section: Elliptical Calderas In the Kenyan Riftmentioning

confidence: 95%

“…Northern Kenya has extended by 35 -40 km (Hendrie et al 1994), in contrast with 4 -20 km of extension in central and southern Kenya (Baker et al 1972). The crustal thickness varies from 20 km at c. 38N to 35 km at the Equator (Prodehl et al 1997). A partially molten upper mantle may underlie the Kenyan Rift, as suggested by low seismic velocities, and may possibly form a series of fractionated magmatic intrusions (Achauer 1992;Achauer et al 1994;Birt et al 1997;Thybo et al 2000;Achauer & Masson 2002).…”

Section: Regional Tectonic Settingmentioning

confidence: 99%

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Influence of regional tectonics and pre-existing structures on the formation of elliptical calderas in the Kenyan Rift

Robertson

Biggs

Cashman

et al. 2015

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Calderas are formed by the collapse of large magma reservoirs and are commonly elliptical in map view. The orientation of elliptical calderas is often used as an indicator of the local stress regime; but, in some rift settings, pre-existing structural trends may also influence the orientation. We investigated whether either of these two mechanisms controls the orientation of calderas in the Kenyan Rift. Satellite-based mapping was used to identify the rift border faults, intra-rift faults and orientation of the calderas to measure the stress orientations and pre-existing structural trends and to determine the extensional regime at each volcano. We found that extension in northern Kenya is orthogonal, whereas that in southern Kenya is oblique. Elliptical calderas in northern Kenya are orientated NW-SE, aligned with pre-existing structures and perpendicular to recent rift faults. In southern Kenya, the calderas are aligned NE-SW and lie oblique to recent rift faults, but are aligned with pre-existing structures. We conclude that, in oblique continental rifts, pre-existing structures control the development of elongated magma reservoirs. Our results highlight the structural control of magmatism at different crustal levels, where pre-existing structures control the storage and orientation of deeper magma reservoirs and the local stress regime controls intra-rift faulting and shallow magmatism.

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Section: Elliptical Calderas In the Kenyan Riftmentioning

confidence: 95%

Section: Regional Tectonic Settingmentioning

confidence: 99%

Influence of regional tectonics and pre-existing structures on the formation of elliptical calderas in the Kenyan Rift

Robertson

Biggs

Cashman

et al. 2015

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“…Two methods can be used to make lower crustal thickness larger than zero: one way is to decrease original thickness ratio of upper crust to lower crust; the other way is to decrease original upper crustal thickness. To ensure the above mentioned parameters reasonable, we referred to the research of Prodehl et al [19] . They [19] set up a rheological structure profile ( Figure 12) from continental crust through transitional crust to oceanic crust when he was studying the Red Sea.…”

Section: Figurementioning

confidence: 99%

“…To ensure the above mentioned parameters reasonable, we referred to the research of Prodehl et al [19] . They [19] set up a rheological structure profile ( Figure 12) from continental crust through transitional crust to oceanic crust when he was studying the Red Sea. In his profile, the original thickness ratio of upper crust to lower crust ranges from 1 : 1 to 2 : 1 (Figure 12, A) in continental rift.…”

Section: Figurementioning

confidence: 99%

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Stretching characteristics and its dynamic significance of the northern continental margin of South China Sea

Zhang

Sun

Zhou

et al. 2008

Sci. China Ser. D-Earth Sci.

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To investigate the thinning of the whole crust, and the contribution of the upper versus lower crust to the stretching since Cenozoic, we calculated the stretching factor of the northern margin of South China Sea with data such as whole crustal thickness, depth of Cenozoic sedimentary basement and the horizontal displacement of faults. An isometric line drawing on whole crustal stretching factor is then obtained. Along the seismic Line 1530 in Baiyun sag, we also calculated the stretching factors of the upper and lower crust. The results suggest that the whole crustal thickness decreases seaward while the whole crustal stretching factor increases from shelf to slope. The Moho upwells highest beneath where the crust is thinned most. The value of the whole crustal stretching factor ranges from 1.5 to 6. Two areas were thinned intensely: the center of Yinggehai Basin, and the Baiyun sag in the Pearl River Mouth Basin. The calculation of the upper and lower crustal stretching factors from DSP1530 in Baiyun sag shows that the original crust of Baiyun sag should be thinned before deformation. Its pre-Cenozoic evolution as well as tectonic position during Cenozoic might be responsible for that.

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Madagascar's escape from Africa: A high‐resolution plate reconstruction for the Western Somali Basin and implications for supercontinent dispersal

Phethean

Kalnins

Hunen

et al. 2016

Geochem Geophys Geosyst

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Accurate reconstructions of the dispersal of supercontinent blocks are essential for testing continental breakup models. Here, we provide a new plate tectonic reconstruction of the opening of the Western Somali Basin during the breakup of East and West Gondwana. The model is constrained by a new comprehensive set of spreading lineaments, detected in this heavily sedimented basin using a novel technique based on directional derivatives of free‐air gravity anomalies. Vertical gravity gradient and free‐air gravity anomaly maps also enable the detection of extinct mid‐ocean ridge segments, which can be directly compared to several previous ocean magnetic anomaly interpretations of the Western Somali Basin. The best matching interpretations have basin symmetry around the M0 anomaly; these are then used to temporally constrain our plate tectonic reconstruction. The reconstruction supports a tight fit for Gondwana fragments prior to breakup, and predicts that the continent‐ocean transform margin lies along the Rovuma Basin, not along the Davie Fracture Zone (DFZ) as commonly thought. According to our reconstruction, the DFZ represents a major ocean‐ocean fracture zone formed by the coalescence of several smaller fracture zones during evolving plate motions as Madagascar drifted southwards, and offshore Tanzania is an obliquely rifted, rather than transform, margin. New seismic reflection evidence for oceanic crust inboard of the DFZ strongly supports these conclusions. Our results provide important new constraints on the still enigmatic driving mechanism of continental rifting, the nature of the lithosphere in the Western Somali Basin, and its resource potential.

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The KRISP 94 lithospheric investigation of southern Kenya — the experiments and their main results

Cited by 41 publications

References 8 publications

Influence of regional tectonics and pre-existing structures on the formation of elliptical calderas in the Kenyan Rift

Influence of regional tectonics and pre-existing structures on the formation of elliptical calderas in the Kenyan Rift

Stretching characteristics and its dynamic significance of the northern continental margin of South China Sea

Madagascar's escape from Africa: A high‐resolution plate reconstruction for the Western Somali Basin and implications for supercontinent dispersal

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