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Timing of Leucogranite Intrusion and Tourmaline Alteration in Zanskar Shear Zone, NW India

 

Gumbaranjon injection network

Roberto Weinberg and Pavlina Hasalova
Monash University, Australia

 

 

 

Timing of leucogranite intrusion and tourmaline alteartion in Zanskar Shear Zone
Both magma intrusion and Qz-Tml alteration can be found as strongly mylonitized by the shear zone, forming layers parallel to the shear plane, to late, post-kinematic dykes and veins, undeformed and cross-cutting the shear zone.

 


Qz-Tml Alteration: Syn-kinematic and Post-kinematic

 

 

 

Boudinaged vein Boudinaged vein
a) Boudinaged quartz vein surrounded by Tml alteration in sheared orthogneiss on Gumbaranjon face. b) Boudinaged quartz vein surrounded by Tml alteration in sheared orthogneiss on Gumbaranjon face.
Post-kinematic vein Post-kinematic vein
c) Post-kinematic Qz-Tml vein altering banded mylonitic orthogneiss with mylonitic leucogranites parallel to shear plane. d) Post-kinematic Qz-Tml vein altering orthogneiss.

 

 


Granite Intrusion: Syn-kinematic and Post-kinematic

 

 

Boudinaged vein Post-kinematic vein
a) Syn- (pre-?) kinematic Tml-leucogranite, isoclinally folded in Bt-schist. b) Sheared Gnt-Ms-Tml-Bt leucogranite with sheared K-feldspar porphyroclasts.
Folded Tml-leucogranite
c) Mylonitic, Tml-Gt-Ms-Bt leucogranite in normal shear zone (point 33 close to Reru).
Post-kinematic vein Post-kinematic vein
e) Post-kinematic leucogranite dykes intruding mylonitic sequence at Gumbaranjon, including bands of layer-parallel syn-kinematic (pre?) mylonitic leucogranites. f) Sheared syn-kinematic (pre-?) Ms-Gt-Tml-(Bt?) pegmatitic leucogranite, intruded by late post-kinematic, Tml-Ms-Gt leucogranite.
Post- into syn-kinematic Post- into syn-kinematic
g) Post-kinematic, Tml-Ms-Gt leucogranite dykes intruding mylonitic Bt-quartzite (black) with a layer-parallel band of syn-kinematic (pre?) mylonitic Ms-Gt-Tml-(Bt?) pegmatitic leucogranite. h) Part of the same block as (c).
Post-kinematic leucogranite Post-kinematic leucogranite
i) Textural and temporal variety of post-kinematic leucogranite intrusions. j) Early, undeformed Tml-leucogranite, with late intrusion of Tml-leucgoranite with irregular contacts and gradational boundaries: hypothesis, remelting. .