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!!!