Geometry, structure and emplacement of mafic dykes in the Red Sea Hills, Sudan

Babiker, Mohamed; Guðmundsson, Ágúst

doi:10.1016/j.jafrearsci.2004.01.003

Cited by 45 publications

(25 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…New dykes emplaced in it would again acquire E-W preferred orientations. Thus, large numbers of parallel dykes that largely define the average direction of the swarm indicate the time-averaged, regional σ 3 , whereas dykes that are at high angles to the general swarm trend indicate temporary (and sometimes spatially localized) rotation of the stress field (Babiker and Gudmundsson 2004).…”

Section: Dyke Trends and Palaeostressesmentioning

confidence: 99%

“…For the others, no margin or only one margin was distinct owing to weathering and soil cover. The measured thicknesses range from 3 to 62 m with a mean of 17 m and median of 10 m. Dyke swarms typically display thickness size distributions that are power law (e.g., Gudmundsson 1995a,b;Babiker and Gudmundsson 2004) or log-normal (e.g., Walker et al 1995). The thickness size distribution for the Nandurbar-Dhule dykes is neither (Fig.…”

Section: Dyke Thicknessesmentioning

confidence: 99%

“…Babiker and Gudmundsson (2004) used aspect ratios of mafic dykes in Sudan to calculate magmatic overpressures. Taking a value of ∼8 km for the depth to the source magma chambers of the Nandurbar- Dhule dykes, based on previous petrological and gravity modelling, we can calculate the magmatic overpressures in the same way.…”

Section: Aspect Ratiosmentioning

confidence: 99%

“…Taking a value of ∼8 km for the depth to the source magma chambers of the Nandurbar- Dhule dykes, based on previous petrological and gravity modelling, we can calculate the magmatic overpressures in the same way. We assumed, as did Gudmundsson (1983) and Babiker and Gudmundsson (2004) for dykes in Iceland and Sudan, respectively, that those Nandurbar-Dhule dykes that have a strike dimension (trace length) shorter than the dip dimension (dyke height above magma chamber, ∼8 km) were emplaced essentially vertically. There is, of course, no a priori reason why these dykes cannot have formed in part by lateral injection, but vertical injection from shallow magma chambers is a plausible assumption for these select dykes.…”

Section: Aspect Ratiosmentioning

confidence: 99%

“…Dykes that never reached the surface can be modelled as circular interior cracks. Volcanic fissures (feeder dykes), and probable feeder dykes exposed at shallow depths in rift zones (such as here) can be modelled as two-dimensional through-the-thickness cracks between two free surfaces, one the Earth's surface and the other the surface of the magma chamber (Babiker and Gudmundsson 2004). The strike dimension (trace length, L) for such dykes is smaller than the dip dimension (height above the chamber), which is treated as being effectively infinite (Gudmundsson 2005).…”

Section: Aspect Ratiosmentioning

confidence: 99%

See 4 more Smart Citations

Structure and emplacement of the Nandurbar–Dhule mafic dyke swarm, Deccan Traps, and the tectonomagmatic evolution of flood basalts

2006

View full text Add to dashboard Cite

Flood basalts, such as the Deccan Traps of India, represent huge, typically fissure-fed volcanic provinces. We discuss the structural attributes and emplacement mechanics of a large, linear, tholeiitic dyke swarm exposed in the Nandurbar-Dhule area of the Deccan province. The swarm contains 210 dykes of dolerite and basalt >1 km in length, exposed over an area of 14,500 km 2 . The dykes intrude an exclusively basaltic lava pile, largely composed of highly weathered and zeolitized compound pahoehoe flows. The dykes range in length from <1 km to 79 km, and in thickness from 3 to 62 m. Almost all dykes are vertical, with the others nearly so. They show a strong preferred orientation, with a mean strike of N88°. Because they are not emplaced along faults or fractures, they indicate the regional minimum horizontal compressive stress (σ 3 ) to have been aligned ∼N-S during swarm emplacement. The dykes have a negative power law length distribution but an irregular thickness distribution; the latter is uncommon among the other dyke swarms described worldwide. Dyke length is not correlated with dyke width. Using the aspect ratios (length/thickness) of several dykes, we calculate magmatic overpressures required for dyke emplacement, and depths to source magma chambers that are consistent with results of previous petrological and gravity modelling. The anomalously high source depths calculated for a few dykes may be an artifact of underestimated aspect ratios due to incomplete along-strike exposure. However, thermal erosion is a mechanism that can also explain this. Whereas several of the Nandurbar-Dhule dykes may be vertically injected dykes from shallow magma chambers, others, particularly the long ones, must have been formed by lateral injection from such chambers. The larger dykes could well have fed substantial (≥1,000 km 3 ) and quickly emplaced (a few years) flood basalt lava flows. This work highlights some interesting and significant similarities, and contrasts, between the Nandurbar-Dhule dyke swarm and regional tholeiitic dyke swarms in Iceland, Sudan, and elsewhere.

show abstract

Section: Dyke Trends and Palaeostressesmentioning

confidence: 99%

Section: Dyke Thicknessesmentioning

confidence: 99%

Section: Aspect Ratiosmentioning

confidence: 99%

Section: Aspect Ratiosmentioning

confidence: 99%

Section: Aspect Ratiosmentioning

confidence: 99%

See 3 more Smart Citations