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Arakapas Fault Zone (S Troodos FZ) (What? (Names (Arakapas Fault Zone (AR…
Arakapas Fault Zone
(S Troodos FZ)
What?
Uplifted oceanic transform fault zone
All parts of oceanic crust = exposed
Zone of intense shearing South of Troodos Ophiolite
Ongoing debate wrt sense of fault mvmt
E-W trending fault
Names
Arakapas Fault Zone (AR PREFERS)
fault surrounding big Arakapas fault
S. Troodos TFZ
Whole area deformated around TF
Limassol Fores
More deformed section ophiolite south of AFZ
Troodos Oph declination
Ophiolite preserves E-W rathern than N-S magnetic declination
Suggests ophiolite was rotated 90° anticlockwise
Study of sed cover (umbers etc)
Most of rotation (~60°) occurred within L. Cretaceous
The rest of rotation occurred before E. Eocene
S Troodos TFZ
Broad area transform fault deformation extending South of Arakapas Fault
THIS IS AN INTERP - AR PREFERS JUST AFZ
Btwn main ophiolite (N) & sed cover (S)
Igneous rocks on south side transform --> on different plate from Troodos?
Observations
On main ophiolite
Sheeted dykes largely trend N-S
Approaching transform,
Dykes bend round, to almost parallel (E-W) with fault
Complex dyke rotations in vicinity of transform
Infer: deformation ↑ intense closer to TFZ
Sediments in TFZ
Interp: Seds deposited from fault scarps within transform
Slide slumps / debris flow / turbidity currents
How? Mass/debris flow processes
Several interp
Early
Transtensional w instrusions & extrusions
Expect LEFT LATERAL SS (ridge offset to R)
Later
Transpressional
More intense shearing
McLeod
Proposed 2 phase development
Evidence exists supporting both of above
Transpression
(shearing first)
Transtension
(later pull-apart extension)
mapped extensional detachment faults within trannsform
strong sed rotation s w unconformities within transform
--> supports 2 phase development
Bramley findings
Mapped s.s. faults on East
Faults often cored by serpentinite
highly sheared serpentinite
Plutonic rocks interleve (ultramafic gabbros)
Bonninitic dykes
What we saw
Serpentinised SZs
E-W sigmoidal (bended) shear zones
Dykes
Trend E-W within transform
Mg-rich e.g. wehrlite
Palaeomag data
Supports dextral transform (right lateral movement)
Clockwise block rotations within TFZ
McLoed revised model
Right lateral strike-slip / clockwise block rotation
V close to offset spreading axis to N
Spreading ridge - transform intersection
displays lotsa local anticlockwise rotation results in dextral s.s.
Debate surrounds sense of TFZ mvmt
Right or left lateral strike slip
Both = plausible w modern analogues