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Stoping of Country Rock by S-type Granite and Late Tortuous Dykes, Czech Republic

 

dyke

Roberto Weinberg, Monash University, Australia

 

 

 

This site records the stoping or break down of country rock by intrusion of granite, and the late intrusions of narrow, tortuous dykes with irregular chilled margins into this granite.

 


 

Stoping of country rock migmatites: Racov quarry in the vicinity of Telc

 

stoping
Stoped angular block of migmatite in S-type granite. Notice straight margins. Granite truncates leucosomes in migmatite blocks. Racov quarry in the vicinity of Telc.
boudin and neck
Detail of previous photograph: truncating of migmatite leucosome by granite. Racov quarry in the vicinity of Telc.
stoping
Stoping of country rock migmatite into S-type granite. Notice angular blocks and straight margins. Granite truncates leucosomes in migmatite blocks. Racov quarry in the vicinity of Telc.
boudin and neck
Detail of previous photograph: a pre-existing boudin and its quartz veined neck stoped into the granite. Racov quarry in the vicinity of Telc.

 


Irregular, late dykes with chilled margins. Racov quarry.

 

irregular dyke
Bifurcating and irregular dyke. Outcrop plane perpendicular to dyke strike.
irregular dyke
Detail.

 

irregular dyke
Irregular, pillowed? tip of a dyke. Outcrop plane perpendicular to dyke strike.
irregular dyke
Irregular dyke margin showing a chilled margin locally transgressed by the granite along the irregularities in the contact.

 

 


Migmatite related directly to S-type granite: Vanov quarry in the vicinity of Telc.

 

agmatite
Agmatite resulting from the brecciation of the country rock by granite intrusion.
agmatite
Agmatite.

 

agmatite
Angular blocks of migmatite inside granite.
agmatite
Block of layered migmatite intruded by granite and thrusted along the granite dyke.
agmatite
Disruption of migmatite by granite all the way down to cm clots of coarse biotite.
agmatite
Dyke of felsic granite with several small inclusions/xenoliths of Bt-rich migmatite country rock and biotite clots. Notice concentration of blocks and clots towards the centre of the dyke, Bagnold effect. VANOV quarry in the vicinity of Telc.

 


Different magmas interacting in migmatite disaggregation. Vanov quarry

 

magmas interacting
Dyke of Bt-rich granite intruding a migmatite with large patches of clean leucosome, showing two magmas migrating through the area during disaggregation of a partially molten migmatite.
magmas interacting
Bt-rich irregular patches within a leucogranite: two different magmas mingling or a heterogeneous magma formed as a result of disaggregation of migmatites.
magmas interacting
Dendritic cordierite on the left, now mostly biotite intergrown with quartz, inside a leucocratic patch in Biotite granite (see Fig. 4a in Barbey, 2007, CMP, for a similar texture). On the right, an irregular patch of Bt-rich granite: two different magmas mingling or a heterogeneous magma formed as a result of disaggregation of migmatites?