Insights to extensional processes during magma assisted rifting: Evidence from aligned scoria cones.

Reviewed by Richard Fletcher

Overview• Studies of continental or passive margin rifting

in and around the Ethiopian rift zone.• Faulting in rift zone, may in part, be due to

magmatic intrusions.• Alignment of scoria cones and flows allow for

insight to development and lifespan of spreading zones.

• Preferential Lithospheric thinning plays a role in the intrusions of magmas.

Local Overview

Continental Rifts

• Generally characterized by the relatively broad zones of ‘mechanical’ extension in which faulting and stretching of the lithosphere accommodates strain. The broad reach of initial strain must shift towards narrow zones of magma intrusion at a new oceanic spreading centre.

Continental Rifts

Magma Induced Rifting

• Thought to have caused extension but is now thought to be a by-product of strains.

• Dike induced normal faulting aligns with more developed rifts such as Iceland.

• Other studies show that magma may ascend through tail-cracks, releasing bends, extensional relay zones, and fault intersections.

Recap

• Scoria cones align with faulting along rift zone. • Extruding magma shows development of

spreading center.• Intrusive magma now the cause of continued

extension and strain.• In real time we are witnessing the

development of and oceanic spreading center.

Thanks!!!