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Serpentinite Formation Divergent p.b. (Oceanic core complexes (Large low…
Serpentinite Formation Divergent p.b.
Tectonic settings
Divergent plate boundaries i.e. slow spreading ridges
Convergent plate boundaries
Serpentinite formation requires:
Mantle rocks
in contact with
water
Serpentinite @ divergent p.b.
Slow spreading ridges
low magma production ∴ crust stretched
Mantle rock brought to surface
along big detachment fault
∴ Serpentinisation can occur on significant scale
lotsa mantle rock in contact with percolating sea water
probably still hot
'Oceanic core complexes' associated
Oceanic core complexes
Long ridge of smooth domes ⊥ mid-ocean ridges
Corrugation (transverse ridges) atop exposed dome
due to scraping of surfaces during faulting
km-scale 'grooves'
Large low angle detachment faults
bring deep rock to surface
accommodate expansion
∴ no rifting occurs
Form @ slow spreading ridges
with limited upwelling magma supply
Core complex builds on uplifted side of fault
Serpentinite @ divergent p.b.
e.g. Atlantis Massif
At depth @ divergent p.b.
Serpentinite formation in upper tens km oceanic crust
Water percolates through fractures
High water pressure @ depth aids fluid flow
∴ Mantle peridotite = serpentinised
Serpentinised zone = thicker where...
Faulting in oceanic lithosphere
--> Facilitates greater water percolation
(hydrothermal circualtion)
∴ Thicker serpentinisation = possible where oceanic crust is faulted
i.e. over 5 km vs few km